The Big Picture | Notes & Critical Review

Posted on February 13, 2017


Sean Carroll. The Big Picture: On the Origins of Life, Meaning, and the Universe Itself. Dutton, 2016. (470 pages)



We have two goals in front of us. One is to explain the story of our universe and why we think it’s true, the big picture as we currently understand it. (3)

The other goal is to offer a bit of existential therapy. I want to argue that, though we are part of a universe that runs according to impersonal underlying laws, we nevertheless matter. (3)

poetic naturalism. “Naturalism” claims that there is just one world, the natural world… “Poetic” reminds us that there is more than one way of talking about the world. We find it natural to use a vocabulary of “causes” and “reasons why” things happen, but those ideas aren’t part of how nature works at its deepest levels. They are emergent phenomena, part of how we describe our everyday world. (4)


1. The Fundamental Nature of Reality

At a fundamental level, there aren’t separate “living things” and “nonliving things,” “things here on Earth” and “things up in the sky,” “matter” and “spirit. There is just the basic stuff of reality, appearing to us in many different forms. | How far will this process of unification and simplification go? It’s impossible to say for sure. But we have a reasonable guess, based on our progress thus far: it will go all the way. We will ultimately understand the world as a single, unified reality, not caused or sustained or influenced by anything outside itself. That’s a big deal. (12-13)

Naturalism isn’t an obvious, default way to think about the world. The case in its favor has built up gradually over the years, a consequence of our relentless quest to improve our understanding of how things work at a deep level, but there is still work to be done. We don’t know how the universe began, or if it’s the only universe. We don’t know the ultimate, complete laws of physics. We don’t know how life began, or how consciousness arose. And we certainly haven’t agreed on the best way to live in the world as good human beings. (13)

The naturalist needs to make the case that, even without actually having these answers yet, their worldview is still by far the most likely framework in which we will eventually find them. That’s what we’re here to do. (14)

The universe is large, and I am a tiny part of it, constructed of the same particles and forces as everything else: by itself, that tells us precisely nothing about how to answer such questions. We’re going to have to be both smart and courageous as we work to get this right. (14)

2. Poetic Naturalism

It just means that the notion of a ship is a derived category in our ontology, not a fundamental one. It is a useful way of talking about certain subsets of the basic stuff of the universe. We invent the concept of a ship because it is useful to us, not because it’s already there at the deepest level of reality. Is it the same ship after we’ve gradually replaced every plank? I don’t know. It’s up to us to decide. (17)

What we’re seeing is the difference between a rich ontology and a sparse one. A rich ontology comes with a large number of different fundamental categories, where by “fundamental” we mean “playing an essential role in our deepest, most comprehensive picture of reality.” (17)

In a sparse ontology, there are a small number of fundamental categories (maybe only one) describing the world. But there will be very many ways of talking about the world. (18)

One benefit of a rich ontology is that it’s easy to say what is “real”–every category describes something real. In a sparse ontology, that’s not so clear.

That’s the most hard-core attitude we could take to reality, sometimes called eliminativism, since its adherents like nothing better than to go around eliminating this or that concept from our list of what is real. (19)

I’m going to argue for a different view: our fundamental ontology, the best way we have of talking about the world at the deepest level, is extremely sparse. But many concepts that are part of non-fundamental ways we have of talking about the world–useful ideas describing higher-level, macroscopic reality–deserve to be called “real.” (19)

The strategy I’m advocating here can be called poetic naturalism.

The universe is made of stories, not of atoms. – Muriel Rukeyser

The world is what exists and what happens, but we gain enormous insight by talking about it–telling its story–in different ways. (19)

Naturalism comes down to three things:

  1. There is only one world, the natural world.
  2. The world evolves according to unbroken patterns, the laws of nature.
  3. The only reliable way of learning about the world is by observing it.

The poetic aspect comes to the fore when we start talking about that world. It can also be summarized in three points:

  1. There are many ways of talking about the world.
  2. All good ways of talking must be consistent with one another and with the world.
  3. Our purposes in the moment determine the best way of talking.

Philosopher Wilfrid Sellars coined the term manifest image to refer to the folk ontology suggested by our everyday experience, and scientific image for the new, unified view of the world established by science. (20)

Within poetic naturalism we can distinguish among three different kinds of stories we can tell about the world. There is the deepest, most fundamental description we can imagine–the whole universe, exactly described in every microscopic detail. (20)

Then there are “emergent” or “effective” descriptions, valid within some limited domain. … Finally, there are values: concepts of right and wrong, purpose and duty, or beauty and ugliness. (21)

Poetic naturalism is a philosophy of freedom and responsibility. … The move from description to prescription, from saying what happens to passing judgment on what should happen, is a creative one, a fundamentally human act. The world is just the world, unfolding according to the patterns of nature, free of any judgmental attributes. The world exists; beauty and goodness are things that we bring to it. (21)

3. The World Moves by Itself

Aristotle’s view of physics was resolutely teleological: he thought of objects as having a natural state of being, and processes as being directed toward a goal. Famously, he suggested that we could distinguish between four different kinds of “causes,” although “kinds of explanation” might be a better translation of what he had in mind. The four kinds were

  • material cause, the stuff of which an object is made
  • formal cause, the essential property that makes an object what it is
  • efficient cause, the thing that brings the object about (closest to our informal notion of “cause”)
  • final cause, the purpose for which an object exists. (25)

Aristotle had a more expansive definition of “motion” than we use today, one that is really closer to “transformation.” … Aristotle’s conviction was that all of these transformations implied the existence of a transforming cause. (27)

4. What Determines What Will Happen?

[Pierre-Simon] Laplace imagined a “vast intellect” that knew the positions and velocities of all the particles in the universe, and understood all the forces they were subject to, and had sufficient computational power to apply Newton’s laws of motion.

…for such an intellect nothing would be uncertain, and the future just like the past would be present before its eyes.

His contemporaries immediately judged “vast intellect” to be too boring, and renamed it Laplace’s Demon. (33)

conservation of information. Just as conservation of momentum implies that the universe can just keep on moving, without any unmoved mover behind the scenes, conservation of information implies that each moment contains precisely the right amount of information to determine every other moment. (34)

determinism. … A more popular objection to determinism is the phenomenon of chaos. … in many kinds of systems, very tiny amounts of imprecision in our knowledge of the initial state of that system can lead to very large variations in where it eventually ends up. (35)

The real universe is nothing like [destiny]. It’s more like an annoying child who likes to approach people and say, “I know what’s going to happen to you next!” Then, when you ask what will happen, the child says, “I can’t tell you.” And after it happens, they say, “See? I knew that was going to happen!” That’s the universe for you. (36)

5. Reasons Why

Principle of Sufficient Reason: For any true fact, there is a reason why it is so, and why something else is not so instead. (40)

abduction, or “inference to the best explanation. … With deduction, we start with some axioms whose truth we do not question, and derive rigorously necessary conclusions from them. With induction, we start with some examples we know about, and generalize to a wider context–rigorously, if we have some reason for believing that such a generalization is always correct, but often we don’t quite have that guarantee. (40-41)

Hume noted that conceiving effects without causes might seem unusual, but it does not lead to any inherent contradiction or logical impossibility. (41)

Metaphysical principles are tempting shortcuts but not reliable guides. There are good reasons why things often seem to happen for reasons–and also reasons why that’s not a bedrock principle. (42)

There are things that happen–that is, states of the universe (or parts thereof) at specific moments in time. And then there are features of the universe, such as the laws of physics themselves. (42)

When it comes to “things that happen,” what we mean by a “reason” is essentially the same as what we man when we refer to the “cause” of an event. (43)

However, that isn’t really what people have in mind when they’re searching for reasons. … What we are really after is some identifiable aspect of the configuration of the universe without which the event in question would not have occurred. (43)

What we might want to ask is: “What is the reason why it makes sense to talk about ‘reasons why’?” And there’s a good answer, namely: because of the arrow of time. (43)

Now we’re trying to figure out why the fundamental fabric of reality is one way rather than some other way. | The secret here is to accept that such questions may or may not have answers. We have every right to ask them, but we have no right at all to demand an answer that will satisfy us. We have to be open to the possibility that they are brute facts, and that’s just how things are. (45)

But the universe, and the laws of physics, aren’t embedded in any bigger context, as far as we know. They might be–we should be open-minded about the possibility of something outside our physical universe, whether it’s a nonphysical reality or something more mundane, like an ensemble of universes that make up a multiverse. (45)

What we can’t do is demand that the universe scratch our explanatory itches. Curiosity is a virtue, and it’s good to look for answers to “Why?” questions whenever we might be able to find them, or when we think that asking such questions might help us to understand things better. But we should be at peace with the possibility that, for some questions, the answer doesn’t go any deeper than “That’s what it is.” (46)

6. Our Universe

Giordano Bruno. Edwin Hubble. Georges Lemaitre. Arno Penzias and Robert Wilson.

So the Big Bang doesn’t actually mark the beginning of our universe; it marks the end of our theoretical understanding. … We shouldn’t think of it as “the singularity at the beginning of time”; it’s a label for a moment in time that we currently don’t understand. (51)

vacuum energy … cosmological constant.

7. Time’s Arrow

It’s been popular to imagine that the world is teleological–directed toward some future goal. But it’s better to think of it as ekinological, from the Greek “εκκινηση,” meaning “start” or “departure.” Everything interesting and complex about the current state of our universe can be traced directly to conditions near its beginning, the consequences of which we are living out every day. (54)

In reality, both directions of time are created equal. The reason why there’s a noticeable distinction between past and future isn’t because of the nature of time; it’s because we live in the aftermath of an extremely influential event: the Big Bang. (55)

There is nothing in the underlying laws that says things can evolve in one direction in time but not the other. Physical motions, to the best of our understanding, are reversible. (55)

The real question is not why we never see eggs un-breaking toward the future; it’s why we see them unbroken in the past. (56)

statistical mechanics. Ludwig Boltzmann.

Rather than thinking of heat and entropy as distinct kinds of things, obeying their own laws of nature, we can think of them as properties of systems made of atoms, and derive those rules from the Newtonian mechanics that applies to everything in the universe. Heat and entropy, in other words, are convenient ways of talking about atoms. (57)

David Albert and Past Hypothesis.

8. Memories and Causes

When we think about cause and effect, by contrast, we single out certain events as uniquely responsible for events that come afterward, as “making them happen.” That’s not quite how the laws of physics work; events simply are arranged in a certain order, with no special responsibility attributed to one over any of the others. We can’t pick out one moment, or a particular aspect of any one moment, and identify it as “the cause.” Different moments in time in the history of the universe follow each other, according to some pattern, but no one moment causes any other. (63)

The law of causality, I believe, like much that passes muster among philosophers, is a relic of a bygone age, surviving, like the monarchy, only because it is erroneously supposed to do no harm. – Bertrand Russell

Understanding context becomes important because our invocation of causality relies on comparing what actually happened to what could have happened, in a different hypothetical world. Philosophers refer to this as modal reasoning–thinking not only about what does happen but about what could happen in possible worlds.

David Lewis.

Why can we say that A causes B, rather than B causes A? Why don’t we think that the reason why Sally swung her elbow is because the glass was going to be knocked off the table? (65)

When a later event has great leverage over an earlier one, we call the latter a “record” of the former; when the earlier event has great leverage over the later one, we call the latter a “cause” of the former. (65)

“Memories” and “causes” aren’t pieces of our fundamental ontology describing our world that we discover through careful research. They are concepts that we invent in order to provide useful descriptions of the macroscopic world. (65-66)


9. Learning about the World

Rev. Thomas Bayes. How well do we know what we think we know? (69)

Even to ask such a question is to admit that our knowledge, at least in part, is not perfectly reliable. This admission is the first step on the road to wisdom. The second step on that road is to understand that, while nothing is perfectly reliable, our beliefs aren’t all equally unreliable either. (69)

What Probability Really Is

frequentists …think that “probability” is just shorthand for “how frequently something would happen in an infinite number of trials.” (70)

Bayesins, for whom probabilities are simply expressions of your states of belief i cases of ignorance or uncertainty. For a Bayesian, saying there is a 50 percent chance of the coin coming up heads is merely to state that you have zero reason to favor one outcome over another. (70)

Often–in fact all the time, if we’re being careful–we don’t hold our beliefs with 100 percent conviction … What we actually have are degrees of belief, which professional statisticians refer to a credences. If you think there’s a 1 in 4 chance it will rain tomorrow, your credence that it will rain is 25 percent. Every single belief we have has some credence attached to it, even if we don’t articulate it explicitly. (70-71)

Bayes’s Theorem, is a way to think about credences. It allows us to answer the following question. Imagine that we have certain credences assigned to different beliefs. Then we gather some information, and learn something new. How does that new information change the credences we have assigned? That’s the question we need to be asking ourselves over and over, as we learn new things about the world. (71)

Every time we reason about the probable truth of different claims, our answers are a combination of the prior credence we assign to that claim and the likelihood of various bits of new information coming to us if that claim were true. (73)

10. Updating Our Knowledge

The Bayesian approach…reminds us that we assign prior credences, and update them appropriately, to every factual proposition that may or may not be true about the world. Does God exist? Can our inner conscious experiences be explained in purely physical terms? Are there objective standards of right and wrong? All of the possible answers to such questions are propositions for which each of us has a prior credence (whether we admit it or not), and which we update when relevant new information comes in (whether we do so correctly or not). (78-79)

Prior beliefs matter. When we’re trying to understand what is true about the world, everyone enters the game with some initial feeling about what propositions are plausible, and what ones seem relatively unlikely. This isn’t an annoying mistake that we should work to correct; it’s an absolutely necessary part of reasoning in conditions of incomplete information. And when it comes to understanding the fundamental architecture of reality, none of us has complete information. (79)

Evidence should move us toward consensus. (80)

But in principle, if we are all trying to be fair and open-minded and willing to change our beliefs in the face of new information, evidence will will out in the end.

…an honest Bayesian updating … the data will wipe out your original prior. That’s called “changing your mind,” and it’s a good thing. Furthermore, since the likelihoods are meant to be objective, gathering more and more data nudges everyone in the direction of the same set of ultimate beliefs about the world.

| That’s how it’s supposed to work anyway. It’s up to each of us to honestly carry out the process in good faith. (81)

Evidence that favors one alternative automatically disfavors others. (81)

In an honest accounting, the credence we assign to a theory should go down every time we make observations that are more probable in competing theories. The shift might be small, but it is there. (82)

All evidence matters.

Bayes teaches us (1) never to assign perfect certainty to any such belief; (2) always to be prepared to update our credences when new evidence comes along; and (3) how exactly such evidence alters the credences we assign. It’s a road map for coming closer and closer to the truth. (83)

11. Is It Okay to Doubt Everything?

Ludwig Wittgenstein. Bertrand Russell. René Descartes. Philip Henry Gosse.

We have every right to give high credence to views of the world that are productive and fruitful, in preference to those that would leave us paralyzed with ennui. (91)

12. Reality Emerges

The progress of human knowledge has bequeathed to us a couple of insights that, taken together, suggest a world that is profoundly different from the picture we construct from our everyday experience. There is conservation of momentum: the universe doesn’t need a mover; constant motion is natural and expected. It is tempting to hypothesize–cautiously, always with the prospect of changing our minds if it doesn’t work–that the universe doesn’t need to be created, caused or even sustained. It can simply be. Then there is conservation of information. The universe evolves by marching from one moment to the next in a way that depends only on its present state. It neither aims toward future goals nor relies on its previous history. (93)

These discoveries indicate that the world operates by itself, free of any external guidance. Together they have dramatically increased our credence in naturalism: there is only one world, the natural world, operating according to the laws of physics. But they also highlight a looming question: Why does the world of our everyday experience seem so different from the world of fundamental physics? Why aren’t the basic workings of reality perfectly obvious at first glance? Why is the vocabulary we use to describe the every-day world–causes, purposes, reasons why–so different from that of the microscopic world–constant motion, Laplacian patterns? (93)

This brings us to the “poetic” part of poetic naturalism. While there is one world, there are many ways of talking about it. we refer to these ways as “models” or “theories” or “vocabularies” or “stories”; it doesn’t matter. (94)

One pivotal word enables that reconciliation between all the different stories: emergence. Like many magical words, it’s extremely powerful but also tricky and liable to be misused in the wrong hands. A property of a system is “emergent” if it is not part of a detailed “fundamental” description of the system, but it becomes useful or even inevitable when we look at the system more broadly. (94)

kinitic theory.

  • The different stories or theories use utterly different vocabularies; they are different ontologies, despite describing the same underlying reality. In one we talk about the density, pressure, and viscosity of the fluid; in the other we talk about the position and velocity of all the individual molecules. Each story comes with an elaborate set of ingredients–objects, properties, processes, relations–and those ingredients can be wildly different from one story to another, even if they are all “true.” (96)
  • Each theory has a particular domain of applicability. The fluid description wouldn’t be legitimate if the number of molecules in a region were so small that the effects of particular molecules were important individually, rather than only in aggregate. The molecular description is effective under wider circumstances, but still not always; we could imagine packing enough molecules into a small enough region of space that they collapsed to make a black hole, and the molecular vocabulary would no longer be appropriate. (96-97)
  • Within their respective domains of applicability, each theory is autonomous–complete and self-contained, neither relying on the other. If we’re speaking the fluid language, we describe the air using density and pressure and so on. Specifying those quantities is enough to answer whatever questions we have about the air, according to that theory. In particular, we don’t need to ever refer to any ideas about molecule and their properties. Historically, we talked about air pressure and velocity long before we knew it was made of molecules. Likewise, when we are talking about molecules, we don’t ever have to use words like “pressure” or “viscosity”–those concepts simply don’t apply. (97)

The important takeaway here is that stories can invoke utterly different ideas, and yet accurately describe the same underlying stuff. … Organisms can be alive even if their constituent atoms are not. Animals can be conscious even if their cells are not. People can make choices even if the very concept of “choice” doesn’t apply to the pieces of which they are made. (97)

One person’s microscopic is another person’s macroscopic. (98)

…emergent theories can be multiply realizable: there can, in principle, be many distinct microscopic theories that are incompatible with one another but compatible with the same emergent description. (99)

…space itself is emergent rather than fundamental. Then it doesn’t even make sense to talk about “a location in space” as a fundamental concept. (100)

Seeing how relatively easy it is to derive fluid mechanics from molecules, one can get the idea that deriving one theory from another is what emergence is all about. It’s not–emergence is about different theories speaking different languages, but offering compatible descriptions of the same underlying phenomena in their respective domains of applicability. If a macroscopic theory has a domain of applicability that is a subset of the domain of applicability of some microscopic theory, and both theories are consistent, then the microscopic theory can be said to entail the macroscopic one; but that’s often something we take for granted, not something that can explicitly be demonstrated. (101)

As systems evolve through time, perhaps in response to changes in their external environment, they can pass from the domain of applicability of one kind of emergent description to a different one–what’s known as a phase transition. (101)

Here is a partial list of important phase transitions in the history of the cosmos:

  • The formation of protons and neutrons out of quarks and gluons in the early universe.
  • Electrons combining with atomic nuclei to make atoms, several hundred thousand years after the Big Bang.
  • The formation of the first stars, filling the universe with new light.
  • The origin of life: a self-sustaining complex chemical reaction.
  • Multicellularity, when different living organisms merged to become one.
  • Consciousness: the awareness of self and the ability to form mental representations of the universe.
  • The origin of language and the ability to construct and share abstract thoughts.
  • The invention of machines and technology.

There are phase transitions int he realm of ideas as well as that of materials. Philosopher of science Thomas Kuhn popularized the idea of a “paradigm shift” to describe how new theories could induce scientists to conceptualize the world in starkly different ways. Even an individual person changing their mind about something can be thought of as a phase transition: our best way of talking about that person is now different. People, like water, can exhibit plateaus in their thinking, where outwardly they hold the same beliefs but inwardly their mental gears are gradually turning. (102-103)

13. What Exists, and What Is Illusion?

Auguste Comte. Ernest Rutherford.

Is an emergent theory just a way of repackaging the microscopic theory, or is it something truly novel? For that matter, is the behavior of the emergent theory derivable, even in principle, from the microscopic description, or does the underlying stuff literally act differently in the macroscopic context? A more provocative way of putting the same questions would be: are emergent phenomena real, or merely illusory? (105)

Philip Anderson.

…an emergent theory can be completely independent of more fine-grained comprehensive descriptions of the same system. The emergent theory is autonomous (it works by itself, without reference to other theories) and multiply realizable (many microscopic theories can lead to the same emergent behavior). (106)

There are several different questions here, which are related to one another but logically distinct.

  1. Are the most fine-grained (microscopic, comprehensive stories the most interesting or important ones?
  2. As a research program, is the best way to understand macroscopic phenomena to first understand microscopic phenomena, and then derive the emergent description?
  3. Is there something we learn by studying the emergent level that we could not understand by studying the microscopic level, even if we were as smart as Laplace’s Demon?
  4. Is behavior at the macroscopic level incompatible–literally inconsistent with–how we would expect the system to behave if we knew only the microscopic rules? (107)

…the emergent theory describes true features of the system that might be completely hidden from the microscopic point of view. You might have a self-contained and comprehensive theory of how things behave, but that doesn’t mean you know everything; in particular, you don’t know all of the useful ways of talking about the system. … From that perspective–the correct one–we really do learn something new by studying emergent theories for their own sakes, even if all the theories are utterly compatible. (108)

strong emergence. …When many parts come together to make a whole, in this view, not only should we be on the lookout for new knowledge in the form of better ways to describe the system, but we should contemplate new behavior. In strong emergence, the behavior of a system with many parts is not reducible to the aggregate behavior of all those parts, even in principle. (109)

So we’re allowed to contemplate alterations in this basic paradigm of physics–but we should be aware of how dramatically we are changing our best theories of the world, just in order to account for a phenomenon (human behavior) that is manifestly extremely complex and hard to understand. (110)

eliminativism. …its proponents want to eliminate talk of mental states entirely. (110)

A poetic naturalist has another way out: something is “real” if it plays an essential role in some particular story of reality that, as far as we can tell, provides an accurate description of the world within its domain of applicability. Atoms are real; tables are real; consciousness is undoubtedly real. (111)

Illusions are just mistakes, concepts that play no useful role in descriptions at any level of coarse-graining. (111)

Poetic naturalism sits in between: there is only one, unified, physical world, but many useful ways of talking about it, each of which captures an element of reality. Poetic naturalism is at least consistent with its own standards: it tries to provide the most useful way of talking about the world we have. (112)

The most seductive mistake we can be drawn into when dealing with multiple stories of reality is to mix up vocabularies appropriate to different ways of talking. (113)

You can think of yourself as an individual human being, or you can think of yourself as a collection of atoms. Just not both at the same time, at least when it comes to asking how one kind of thing interacts with another one. (113)

…the separation between different ways of talking–“effective field theories”–is precise and well-defined. (113)

14. Planets of Belief

…how do we construct a comprehensive picture of how things work that is both reliable and consistent with our experience? (115)


In this picture, a planet of belief is much richer and more complex than simply an ontology. An ontology is a view about what really exists; a planet of belief contains all sorts of other convictions, including methods for understanding the world, a priori truths, derived categories, preferences, aesthetic and ethical judgments, and more. If you believe that two plus two equals four and chocolate ice cream is objectively better than vanilla, those are not parts of your ontology, but they are parts of your planet of belief. (117)

coherentism. According to this picture, a justified belief is one that belongs to a coherent set of propositions. (117)

When two dramatically incompatible beliefs come into direct contact, it can be like highly reactive chemicals being mixed together, leading to an impressive explosion–possibly even blowing the entire planet apart, until a new one can be reassembled from different parts. (117)

Ideally, we should be constantly testing and probing our planets of belief for inconsistencies and structural deficiencies. Precisely because they are floating freely through space, rather than remaining anchored on solid and immovable ground, we should always be willing to improve on our planets’ composition and architecture, even to the point of completely jettisoning old beliefs and replacing them with better ones. (117)

As a matter of empirical fact, there are a number of important, common beliefs that almost everyone shares. Most people believe that reason and logic play an important role in finding truth. (118)

What rescues our beliefs from being completely arbitrary is that one of the beliefs in a typical planet is something like “true statements correspond to actual elements of the real world.” If we belief that, and have some reliable data, and are sufficiently honest with ourselves, we can hope to construct belief systems that not only are coherent but also agree with those of other people and with external reality. (118-119)

There is a crucial difference, in other words, between stable planets of beliefs…and habitable planets. … We can hope that people working in good faith will, after trying hard to understand reality the best they can, end up constructing planets of belief that are somewhat compatible with one another. (119)

We shouldn’t overestimate people’s rationality or willingness to look at new evidence objectively as possible. (119)

cognitive dissonance. Leon Festinger. Dorothy Martin (Marian Keech).

Human beings are not nearly as coolly rational as we like to think we are. Having set up comfortable planets of belief, we become resistant to altering them, and develop cognitive biases that prevent us from seeing the world with perfect clarity. We aspire to be perfect Baysian abductors, impartially reasoning to the best explanation–but most often we take new data and squeeze it to fit with our preconceptions. (120)

It’s worth highlighting two important cognitive biases that we can look to avoid as we put together our own planets. One is our tendency to give higher credences to propositions that we want to be true. This can show up at a very personal level, as what’s known as self-serving bias: when something good happens, we think it’s because we are talented and deserving, while bad things are attributed to unfortunate luck or uncontrollable external circumstances. (120)

The other bias is our preference for preserving our planet of belief, rather than changing it around. …Confirmation bias is our tendency to latch on to and highlight any information that confirms beliefs we already have, while disregarding evidence that may throw our beliefs into question. This tendency is so strong that it leads to the backfire effect–show someone evidence that contradicts what they belief, and studies show that they will usually come away holding their initial beliefs more strongly. (120)

Carol Tavris and Elliot Aronson talk about the “Pyramid of Choice.”

We’re faced with the problem that the beliefs we choose to adopt are shaped as much, if not more, by the beliefs we already have than by correspondence with external reality. (121)

How can we guard ourselves against self-reinforcing irrationality? There is no perfect remedy, but there is a strategy. Knowing that cognitive biases exist, we can take that fact into account when doing our Bayesian inference. Do you want something to be true? That should count against it in your assignment of credences, not for it. Does new, credible evidence seem incompatible with your worldview? We should give it extra consideration, not toss it aside. (121)

A Utopia of rationality might not be achievable by flawed human beings, but it’s something to which we can aspire. (121)

Robert Aumann.

15. Accepting Uncertainty

Science never proves anything. (123)

We should always imagine that there is some nonzero likelihood for absolutely any observation in absolutely any theory. (127)

As a result, our credences never go all the way to zero — nor precisely to 100 percent, since there are always competing possibilities. And it’s a good thing that credences never reach these points of absolute certainty; if they did, no amount of new evidence could ever change our minds. That’s no way to go through life. (127)

The word “faith” is highly charged, and this isn’t the place to argue over how it should be defined. Let us merely note that sometimes faith is taken as something that is absolutely certain. (128)

It is this kind of stance – that there is a kind of knowledge that is certain, which we should receive with docility, to which we should submit – that I’m arguing against. There are no such kinds of knowledge. We can always be mistaken, and one of the most important features of a successful strategy for understanding the world is that it will constantly be testing its presuppositions, admitting the possibility of error, and trying to do better. We all want to live on a stable planet of belief, where the different parts of our worldview fit together harmoniously; but we want to avoid being sucked into a black hole of belief, where our convictions are so strong that we can never escape, no matter what kind of new insight or information we obtain.

You will sometimes hear the claim that even science is based on a kind of “faith,” for example, in the reliability of our experimental data or in the existence of unbreakable physical laws. That is wrong. As part of the practice of science, we certainly make assumptions–our sense data is giving us roughly reliable information about the world, simple explanations are preferable to complex ones, we are not brains in vats, and so forth. But we don’t have “faith” in those assumptions; they are components of our planets of belief, but they are always subject to revision and improvement and even, if necessary, outright rejection. By its nature, science needs to be completely open to the actual operation of the world, and that means that we stand ready to discard any idea that is no longer useful, no matter how cherished and central it may once have seemed. (128)

Because we should have nonzero credences for ideas that might seem completely unlikely or even crazy, it becomes useful to distinguish between “knowing” and “knowing with absolute logical certainty.” If our credence for some proposition is 0.0000000001, we’re not absolutely certain it’s wrong–but it’s okay to proceed as if we know it is. (129)

The resolution is to admit that some credences are so small that they’re not worth taking seriously. It makes sense to act as if we know those possibilities to be false. (129)

So we take “I believe x” not to mean “I can prove x is the case,” but rather “I feel it would be counterproductive to spend any substantial amount of time and effort doubting x.” (129)

We are left with, not absolute proof of anything, but a high degree of confidence in some things, and greater uncertainty in others. That’s both the best we can hope for and what the world does as a matter of fact grant us. Life is short, and certainty never happens. (129)

16. What Can We Know about the World without Actually Looking at It?

“Transcendent,” from the Latin transcendere, “climb over, surpass,” is a word we attach to experiences that seem to reach beyond our mundane physical situation. (131)

For our present purposes, we want to know what transcendent experiences imply about the structure of the world. Do they arise from the behavior of the atoms and neurons in our physical brains, or should we think of such moments as indications of contact with a numinous realm, something truly beyond the physical What, in other words, does transcendence teach us about ontology? (131)

Behind these questions lurks an even bigger issue. Science advances by observation and experiment: we pose hypotheses about how the world works an then test them by collecting new information and performing the appropriate Bayesian updating. But is that the only way to learn about the world? Isn’t it at least conceivable that we could come to knowledge of reality in ways other than the scientific, using methods other than hypothesis testing and collecting data? (131)

theorems. Bernhard Riemann.

We can think of the difference between math and science in terms of possible worlds. Math is concerned with truths that would hold in any possible world: given these axioms, these theorems will follow. Science is all about discovering the actual world in which we live. (132)

methodological naturalism.

Because science is limited to explaining the natural world by means of natural processes, it cannot use supernatural causation in its explanations. Similarly, science is precluded from making statements about supernatural forces because these are outside its provenance. (National Academy of Sciences)

Not really. Science should be interested in determining the truth, whatever that truth may be–natural, supernatural, or otherwise. (133)

Science isn’t characterized by methodological naturalism but by methodological empiricism–the idea that knowledge is derived from our experience of the world, rather than by thought alone. Science is a technique, not a set of conclusions. (133)

Science has a simple goal: to figure out what the world actually is. Not all the possible ways it could be, nor the particular way it should be. Just what it is. (134)

The relationship between science and naturalism is not that science presumes naturalism; it’s that science has provisionally concluded that naturalism is the best picture of the world we have available. We lay out all of the ontologies we can think of, assign some prior credences to them, collect as much information we can, and update those credences accordingly. At the end of the process, we find that naturalism gives the best account of the evidence we have, and assign it the highest credence. New evidence could lead to future adjustments in our credences, but right now naturalism is well out ahead of the alternatives. (134)

rationalism, the idea that we can come to true knowledge of the world by methods other than through our sensory experience. (134)

A related route to rationalism is based on the belief that the world has an underlying sensible or logical order, an from this order we can discern a priori principles that simply have to be true, without any need to check up on them by collecting data. Examples might include “for every effect there is a cause,” or “nothing comes from nothing.” (135)

Gottfried Wilhelm Leibniz. John Calvin. Alvin Plantinga. Aldous Huxley, The Doors of Perception (pdf). Robin Carhart-Harris and David Nutt.

…if we want to undertake our journey to the best possible understanding of the world with the intellectual honesty it deserves, we always have to question our beliefs, consider alternatives, and compare them with the best evidence we can gather. It may be the case that transcendent experiences arise from a direct connection with a higher level of reality, but the only way to know is to weigh that idea against what we learn from the world by looking at it. (138)

17. Who Am I?

Ben / Barbara Barres. Our opinion of a person is greatly affected by what sex we perceive them to be. (140)

If eliminativism is the urge to declare as many things illusory as possible, its opposite is essentialism; the tendency to take certain categories as immovable features of the bedrock of reality. (141)

Poetic naturalism sees things differently. Categories such as “male” and “female” are human inventions — stories we tell because it helps us make sense of our world. (142)

This can sound reminiscent of the old postmodern slogan that “reality is socially constructed.” There’s a sense in which that’s true. What’s socially constructed are the ways we talk about the world, and if a particular way of talking involves concepts that are useful and fit the world quite accurately, it’s fair to refer to those concepts as “real.” But we can’t forget that there is a single world underlying it all, and there’s no sense in which the underlying world is socially constructed. It simply is, and we take on the task of discovering it and inventing vocabularies with which to describe it. (142)

The question, however, is whether a particular way of talking about the world is useful. And usefulness is always relative to some purpose. If we’re being scientists, our goal is to describe and understand what happens i the world, and “useful” means “providing an accurate model of some aspect of reality.” (143)

18. Abducting God

What should our priors be for theism and atheism? (146)

Let’s call it a wash. You are entitled to your own priors, but for purposes of this discussion let’s imagine that the prior credences for theism and atheism are about equal. Then all of the heavy lifting will be done by the likelihoods–how well the two ideas do in accounting for the world we actually see. (146)

Whatever biases I may have, I need to keep them in mind while trying to objectively weigh the evidence. It’s all any of us can hope to do from our tiny perch in the cosmos. (149)


19. How Much We Know

J.B. Rhine. James Randi. …what we know about the laws of physics is sufficient to rule out the possibility of true psychic powers. (154)

I’m not claiming that we know everything, or anywhere close to it. I’m claiming that we know some things, and that those things are enough to rule out some other things. … Modern physics not only tells us that certain things are true; it comes with a built-in way of delineating the limits of that knowledge — where our theories cease to be reliable. (155)

We never know anything about the empirical world with absolute certainty. We must always be open to changing our theories in the face of new information. (156)

But we can, in the spirit of the later Wittgenstein, be sufficiently confident in some claims that we treat the matter as effectively settled. (157)

David Hume, An Enquiry Concerning Human Understanding.

20. The Quantum Realm

Zou Enlai. Richard Feynman. The “Rutherford model” of the atom.

When we say that a quantum state is a superposition, we don’t mean “it could be any one of various possibilities, we’re not sure which.” We mean “it is a weighted combination of all those possibilities at the same time.” If you could somehow play “quantum poker,” your opponent would really have some combination of each of the possible hands all at once, and their hand would become one specific alternative only once they turned over the cards for you to look at them. (163)

Erwin Schrödinger equation.

21. Interpreting Quantum Mechanics

…the measurement problem of quantum mechanics. (166)

antirealist. Niels Bohr. Hugh Everett IIIentanglement. Max BornMany-Worlds Interpretationdecoherence.

There are two important things to take away from this discussion, as far as the big picture is concerned. One is that, while we don’t have a finished understanding of quantum mechanics at a fundamental level, there is nothing we know about it that necessarily invalidates determinism (the future follows uniquely from the present), realism (there is an objective real world), or physicalism (the world is purely physical). (170-171)

The other important takeaway is a feature common to all interpretations of quantum mechanics: what we see when we look at the world is quite different from how we describe the world when we’re not looking at it. … In a sense it is the ultimate unification: not only does the deepest layer of reality not consist of things like “oceans” and “mountains”; it doesn’t even consist of things like “electrons” and “photons.” It’s just the quantum wave function. Everything else is a convenient way of talking. (171)

22. The Core Theory

Our best theory of the world…takes unification one step further, to say that both particles and forces arise out of fields. A field is kind of the opposite of a particle; while a particle has a specific location in space, a field is something that stretches all throughout space, taking on some particular value at every point. (172-173)

quantum field theory.

The ordinary stuff out of which you and I are made, as well as the Earth and everything you see around you, only really involves three matter particles and three forces. Electrons in atoms are bound to the nucleus by electromagnetism, and the nucleus itself is made of protons and neutrons held together by the nuclear force, and of course everything feels the force of gravity. Protons and neutrons, in turn, are made out of two kinds of smaller particles: up quarks and down quarks. They are held together by the strong nuclear force, carried by particles called gluons. The “nuclear force” between protons and neutrons is a kind of spillover of the strong nuclear force. There’s also a weak nuclear force, carried by W and Z bosons, which lets other particles interact with a final kind of fermion, the neutrino. And the four fermions (electron, neutrino, up and down quarks) are just one generation out of a total of three. Finally, in the background lurks the Higgs field, responsible for giving masses to all the particles that have them. (174)

the standard model of particle physicsgeneral relativity.

Frank WilczekCore Theory. …the quantum field theory of the quarks, electrons, neutrinos, all the families of fermions, electromagnetism, gravity, the nuclear forces, and the Higgs. (176)

We can be confident that the Core Theory, accounting for the substances and processes we experience in our everyday life, is correct. … From the perspective of poetic naturalism, there is one story of reality we can tell with confidence, in a well-defined domain of applicability. We can’t be metaphysically certain of this; it’s not something we can prove mathematically, since science never proves things. But in any good Baysian accounting, it seems overwhelmingly likely to be true. The laws of physics underlying everyday life are completely know. (177)

23. The Stuff of Which We Are Made

When we’re talking about scientific theories, powerful actually means restrictive — a powerful theory is one in which there are many things that simply cannot happen. (178)

The situation now really is different from the way it has ever been at previous moments in the history of science. Not only do we have a successful theory, but we also know how far that theory can be extended before it ceases to be reliable. That’s just how powerful quantum field theory is. (179)

The logic behind our audacious claim is simple:

  1. Everything we know says that quantum field theory is the correct framework for describing the physics underlying everyday life.
  2. The rules of quantum field theory imply that there can’t be any new particles, forces, or interactions that could be relevant to our everyday lives. We’ve found them all. (179)

Steven Weinberg.

If any particle we haven’t yet found lasted long enough and interacted with ordinary matter with sufficient strength that it could possibly affect the physics of everyday goings-on, we would have produced it in experiments by now. (183)

the graviton.

Here in our daily environment, the world of people and cars and houses, we have a complete inventory of the particles and forces and interactions that are strong enough to have any noticeable effect on anything. That’s a tremendous intellectual achievement, one of which the human race can be justifiably proud. (185)

24. The Effective Theory of the Everyday World

effective field theory. Kenneth Wilson.

…the actual entities we’re talking about–the ontology of the theory–can be completely different in the effective theory from that of a more comprehensive microscopic theory. The microscopic theory has quarks; the effective theory has protons and neutrons. It’s an example of emergence: the vocabulary we use to talk about fluids is completely different from that of molecules, even though they can both refer to the same physical system. (188)

Two features characterize how wonderfully simple and powerful effective field theories are. First, for any one effective theory, there could be many different microscopic theories that give rise to it. That’s multiple realizability in the context of quantum physics. Consequently, we don’t need to know all the microscopic details to make confident statements about macroscopic behavior. Second, given any effective theory, the kinds of dynamics it can have are generally extremely limited. There simply aren’t that many different ways that quantum fields can behave at low energies. (188)

Newtonian theory is a good approximation in a certain domain of applicability, but ultimately ti breaks down and we need a better description of reality. (191)

With effective field theory, however, that’s exactly what we have. An effective field theory describes everything that happens to a certain set of fields, as long as the energies are lower than a certain cutoff, and distances are larger than a certain lower limit (as set by experiment). Once we have the parameters of the effective theory pinned down, we know what will happen to our fields in any experiment we can imagine within its domain of applicability, even if we haven’t done that experiment yet. (191)

It’s this special feature of quantum field theory that gives us the confidence to make such audacious claims about the scope of our knowledge. (191)

The success of the Core Theory, and our understanding of its domain of applicability, thanks to the principles of effective field theory, implies that there is an enormous presumption (a high Baysian credence) in favor of understanding macroscopic phenomena in terms that are compatible with the underlying laws of physics. There can always be exceptions. But as David Hume would have said, if you believe that nay one particular case is a true example of the Core Theory being violated, your evidence in favor of it needs to be strong enough to overcome the enormous amounts of evidence to the contrary. (192)

25. Why Does the Universe Exist?

“On the Ultimate Origin of Things” by Gottfried Leibniz. Derek Parfit. Sidney Morgenbesser.

  1. Could the universe, possibly, simply exist?
  2. What is the best explanation for the existence of the universe?

Poetic naturalists don’t like to talk about necessities when it comes to the universe. They prefer to lay all the options on the table, then try to figure out what our credences should be in each of them. Maybe there is an ultimate explanation; maybe there is an infinite chain of explanations; maybe there is no final explanation at all. The progress of modern physics and cosmology has sent a fairly unequivocal message: there’s nothing wrong with the universe existing without any external help. Why it exists the particular way it does, rather than some other way, is worth exploring. (196)

There are two possibilities: one where the universe is eternal, one where it had a beginning. (197)

Stephen Hawking. James Hartle.

the cosmological argument:

  1. Whatever begins to exist, has a cause.
  2. The universe begins to exist.
  3. Therefore, the Universe had a cause.

The first premise is false. Talking about “causes” is not the right vocabulary to use when thinking about how the universe works at a deep level. We need to be asking ourselves not whether the universe had a cause but whether having a first moment in time is compatible with the laws of nature. (199)

…saying that the universe had a beginning is not the same as saying it popped into existence. (199)

…when we’re talking about the universe, that “earlier” moment simply does not exist. There is not a moment in time where there is no universe, and another moment in time where there is; all moments in time are necessarily associated with an existing universe. The question is whether there can be a first such moment, in an instant of time prior to which there were no other instances. That’s a question our intuitions just aren’t up to addressing.

| Said another way: even if the universe has a first moment of time, it’s wrong to say that it “comes from nothing.” That formulation places into our mind the idea that there was a state of being, called “nothing,” which then transformed into the universe. That’s not right; there is no state of being called “nothing,” and before time began, there is no such thing as “transforming.” What there is, simply, is a moment of time before which there were no other moments.

| The second mistake is to assert that things don’t simply pop into existence, rather than asking why that doesn’t happen in the world we experience. (200)

To the question of whether the universe could possibly exist all by itself, without any external help, science offers an unequivocal answer: sure it could. We don’t yet know the final laws of physics, but there’s nothing we know about how such laws work that suggests the universe needs any help to exist. (201)

Parmenides put forward the famous maxim ex nihilo, nihil fit–“out of nothing, nothing comes.” (201)

There is no reason why the universe couldn’t have had a first moment in time, nor is there any reason it couldn’t have lasted forever, even without the benefit of any external causal or sustaining influences. Our job, as always, is to ask how well competing theories account for the information we accumulate as we observe the actual universe. (202)

Our job, in other words, is to move from the first question, “Can the universe simply exist?” (yes, it can) to the second, harder one: “What is the best explanation for the existence of the universe?”

| The answer is certainly, “We don’t know.” (202)

God isn’t a necessary being, because there are no such things as necessary beings. … We can’t short-circuit the difficult task of figuring out what kind of universe we live in by relying on a priori principles. (203)

26. Body and Soul

Princess Elisabeth of Bohemia.

If you want to say that the mind is a separate substance, not just a way of talking about the collective effect of all those particles, how does that substance interact with the particles? How are the equations of the Core Theory incorrect, and how should we improve them? (205)

Elisabeth Simmern van Pallandtsubstance dualism.

…a mastery of formal etiquette with an intellectual’s impatient distaste for beating around the bush. (209)

If you’re confused, you should be, since Descartes’s story makes no sense. Ironically, though, it’s close to correct. To a poetic naturalist, “mind” is simply a way of talking about the behavior of certain collections of physical matter, just as “heaviness” is. (212)

the pineal gland…the only part of the human brain that was unified rather than split bicamerally… (211)

Nicolas Malebranche.

To imagine that the soul pushes around the electrons and protons and neutrons in our bodies in a way that we haven’t yet detected is certainly conceivable, but it implies that modern physics is profoundly wrong in a way that has so far eluded every controlled experiment ever performed. (212)

Gilbert Ryle … “the dogma of the Ghost in the Machine.”

We certainly don’t have a comprehensive understanding of how matter in motion gives rise to thought and feeling. But from what we do understand, that seems like a much simpler task than making sense of how the mind could be a completely distinct category of existence. (213)

Property dualism is the idea that there’s only one kind of stuff–matter–but it has both physical properties and mental properties. (213)

Elisabeth was a devoted Christian of the late Reformation, not a modern-day naturalist. It is her attitudes and methodology, not her beliefs that make her a hero for this book. She was not content to posit an attractive picture of the world, such as mind/body dualism, and move on from there without further questioning. How would it work? How does this move that? How would we know? Good questions to be asking, no matter how you ultimately view the fundamental nature of reality. (214)

27. Death Is the End

Whether you are a physicalist who believes that there is nothing to us other than the particles of the Core Theory, or someone who thinks that there is some crucial nonphysical component to a human being, everyone admits that the particles are part of who we are. If you want to say there is something else, you have to explain how that something else interacts with the particles. How, in other words, the Core Theory is incomplete, and has to change. (215)

If you want to be a dualist and believe in an immaterial soul that plays any role whatsoever in who we are as human beings, these questions are not optional. We’re not rigging the game by demanding a full-blown mathematical theory of the soul itself; we’re simply asking how the soul is supposed to affect the mathematical theory of the quantum fields that we already have. (216)

There’s nothing wrong with doing elaborate double-blind studies to look for parapsychological or astrological effects, but the fact that such effects are incompatible with the known laws of physics means that you would be testing hypotheses that are so extremely unlikely as to render it hardly worth the effort. (218)

There is a much more profound implication of accepting the Core Theory as underlying the world of our everyday experience. Namely: there is no life after death. We each have a finite time as living creatures, and when it’s over, it’s over. (218)

…the information that makes up “you” is contained in the arrangement of atoms that makes up your body, including your brain. There is no place for that information to go, or any way for it to be preserved, outside your body. (218)

The trick is to think of life as a process rather than a substance. When a candle is burning, there is a flame that clearly carries energy. When we put the candle out, the energy doesn’t “go” anywhere. The candle still contains energy in its atoms and molecules. What happens, instead, is that the process of combustion has ceased. Life is like that: it’s not “stuff”; it’s a set of things happening. When that process stops, life ends. (219)

Life is a way of talking about a particular sequence of events taking place among atoms and molecules arranged in the right way. (219)

vitalism. Henri Bergson. “Phlogiston.” “caloric.”

Over and over, something that we once thought of as a distinct kind of substance has been revealed to be a particular property of ordinary matter in motion. Life is no different. (219)

Quantum fields, however, are indisputably part of who we are. If they are all of who we are, we should have no problem drawing implications of that fact for our lives. If there is something in addition to the quantum fields, it is reasonable to seek an understanding of (and evidence for) that something that is just as precise and rigorous and reproducible as the one we have for field theory. (220)

If we are collections of interacting quantum fields, the implications are enormous. … The laws of physics governing those fields are resolutely impersonal and non-teleological. Our status as parts of the physical universe implies that there is no overarching purpose to human lives, at least not any inherent in the universe beyond ourselves. Th very notion of a “person” is ultimately a way of talking about certain aspects of the underlying reality. It’s a good way of talking, and we have good reasons to take seriously all of the ramifications of that description, including the fact that human beings have individual purposes and can make decisions for themselves. It’s when we start imagining powers or behaviors that contradict the laws of physics that we go astray. (220-221)

If the world we see in our experiments is just a tiny part of a much bigger reality, the rest of reality must somehow act upon the world we do see; otherwise it doesn’t matter very much. And if it does act upon us, that implies a necessary alteration in the laws of physics as we understand them. Not only do we have no strong evidence in favor of such alterations; we don’t even have any good proposals for what form they could possibly take. (221)

The burden for naturalists, meanwhile, is to show that a purely physical universe made of interacting quantum fields is actually able to account for the macroscopic world of our existence. Can we understand how order and complexity arise in a world without transcendent purpose, even in the face of increasing disorder as implied by the second law of thermodynamics? Can we make sense of consciousness and our inner experience without appealing to substances or properties beyond the purely physical? Can we bring meaning and morality to our lives, and speak sensibly about what is right and what is wrong? (221)


28. The Universe in a Cup of Coffee

William Paley. Immanuel Kant. Francisco Ayala. Theodosius Dobzhansky.

How in the world did something as organized as a human being ever come to be? | The short answer comes in two parts: entropy and emergence. Entropy provides an arrow of time; emergence gives us a way of talking about collective structures that can live and evolve and have goals and desires. (227)

Ludwig Boltzmann explained entropy to us: it’s a way of counting how many possible microscopic arrangements of the stuff in a system would look indistinguishable from a macroscopic point of view. If there are many ways to rearrange the particles in a system without changing its basic appearance, it’s high-entropy; if there are a relatively small number, it’s low-entropy. (227)

Scott Aaronson, Varun Mohan, Lauren Ouellette, Brent Wernessapparent complexity. [Quantifying the Rise and Fall of Complexity in Closed Systems – The Coffee Automaton]

There is no law of nature, therefore, that says complexity necessarily develops as systems evolve from low entropy to high entropy. But it can develop–whether it does or not depends on the details of the system you are thinking of. (234)

The appearance of complexity isn’t just compatible with increasing entropy; it relies on it. Imagine a system that din’t have any Past Hypothesis, and was simply in a high-entropy equilibrium state right from the start. Complexity would never develop; the whole system would remain featureless and uninteresting (apart from rare random fluctuations) for all time. The only reason complex structures form at all is because the universe is undergoing a gradual evolution from very low entropy to very high entropy. “Disorder” is growing, and that’s precisely what permits complexity to appear and endure for a long time. (235)

We should enjoy the ride. (236)

29. Light and Life

Giovanni Schiaparelli. Percival Lowell. Erwin Schrödingerfree energy.

30. Funneling Energy

proton-motive force. Peter Mitchell. Jennifer Moyle.

Design tends to be specific, and brittle. … Biological organisms, which have developed over the years with no specific purpose in mind, tend to be more flexible, multipurpose, and self-repairing. (247)

Cells do’t merely tolerate chaos; they harness it. They have little choice, given the environment in which microbiology takes place. (247)

Peter Hoffmann. “molecular storm.”

31. Spontaneous Organization

Jan Baptist van Helmont. Stanley Miller and Harold Urey.

Today we don’t think that Miller and Urey were correctly modeling conditions on the early Earth. Their experiment nevertheless demonstrated a crucial biochemical fact: it’s not that hard to make amino acids. (251)

Let’s focus on three features that seem to be ubiquitous in life as we know it:

  1. Compartmentalization. Cells, the building blocks of living organisms, are bounded by membranes that separate their inner structure from the outside world.
  2. Metabolism. Living creatures take in free energy, and use it to maintain their form as well as performing actions.
  3. Replication with variation. Living beings create more of themselves, passing along information about their structure. Small variations in that information enable Darwinian natural selection.

self-organization. That’s what we call it when a large system, consisting of many smaller subsystems, falls into orderly patterns of configuration or behavior, even though the subsystems all behave independently, and with no special goal in mind. (252)

Thomas Schelling.

One important point about Schelling’s theory is that the way we model the evolution of the system is not reversible.  The dynamics are not “laplacian”; information is not conserved. It is therefore not a model of the real world at its most fundamental level. But it can be a perfectly good emergent description of coarse-grained dynamics, as long as the system as a whole is far from equilibrium. The process of an X or O noticing that it’s unhappy and moving to a randomly chosen empty space is one that necessarily increases the entropy of the universe in the process. Information is lost, since many initial configurations could lead to the same final one. Entropy increases, but the way it increases is by creating an impermanent structure with a high degree of order and complexity. (254)

Lipids have a “head” that is hydrophilic (attracted to water) on one end, and a “tail” that is hydrophobic (repelled by water on the other. (254)

The lipid’s search for contentment is a metaphorical way of talking about the fact that the system evolves so as to minimize free energy. (255)


It therefore seems likely that the earliest form of cellular membranes were actually made of fatty acids rather than phospholipids. (256)

Without compartments and membranes, we’re faced with a soupy mess of compounds, energy sources, and reactions. Once a boundary forms between different kinds of stuff, we can readily talk about the “object” (inside the boundary) and its environment (everything outside). The boundary–whether it’s literally a cell membrane, or the skin or exoskeleton of a multicellular organism–both helps the structure take advantage of the free energy around it and helps us talk about it in useful, computationally efficient ways. (257)

Karl FristonMarkov blanket. Judea Pearl.

Our brains construct models of their surroundings, with the goal of not being surprised very often by new information. That process is precisely Baysian reasoning–subconsciously, the brain carries with it a set of possible things that could happen next, and updates the likelihood of each of them as new data comes in. (258)

32. The Origin and Purpose of Life

Michael Russell.

If you want to understand how life began, it makes sense to begin by looking for features that are shared by existing forms of life. (261)

Peter Mitchell and Jennifer Moyle. William Martin and Nick Lanecatalysisdisequilibrium. Gretchen Früh-Green. Deborah Kelley.

life is nothing but an electron looking for a place to rest.Albert Szent-Györgyi.

There is free energy locked up in certain chemical configurations, and life is one way it can be released. One compelling aspect of the picture is that it’s not simply working backward from “We know there’s life; how did it start?” Instead, it’s suggesting that life is the solution to a problem: “We have some free energy; how do we liberate it?” (263)

John von Neumann. Erwin SchrödingerWhat Is Life? Francis Crick and James Watson. David Bartell and Jack Szostak. Tracey Lincoln and Gerald Joyce.

There is no reason to think that we won’t be able to figure out how life started. No serious scientist working on the origin of life, even those who are personally religious, points to some particular process and says, “here is the step where we need to invoke the presence of a nonphysical life-force, or some element of supernatural intervention.” There is a strong conviction that understanding abiogenesis is a matter of solving puzzles within the known laws of nature, not calling for help from outside of them. (270)

Fred Hoyle.

We’ve made amazing progress in understanding what life is an how it came to be, and there’s eery reason to think that progress will continue until we have figured it out. The work ahead will involve chemistry, physics, mathematics, and biology, not magic. (272)

33. Evolution’s Bootstraps

Richard Lenski. Gregor Mendel.

Many features of the genome of any individual species are going to be the results of accidents rather than any particular adaptation. This is known as genetic drift. (276)

Stephen Jay Gould and Richard Lewontin.

So the real world is a beautiful mess. Is this kind of undirected mechanism–just what we would expect in a universe governed by unthinking underlying laws and with a strong arrow of time–sufficient to account for all the spectacular intricacy of our planet’s biosphere? “There is grandeur in this view of life,” Darwin writes in On the Origin of Species. But is his simple mechanism really enough to make dolphins and butterflies and rain forests from a meager collection of organic molecules fighting for free energy? Can the wonders of efficiency and ingenuity we see in biological organisms really come about from random variation plus time? (Hint: yes.) (278)

34. Searching through the Landscape

Melanie Mitchell. Michael Behe. John McDonald and Alex Fidelibus. William Paley.

35. Emergent Purpose

The evolution of life provides a rich source of higher-level phenomena emerging from the fundamental description of reality, including phenomena that have no direct analogue at the deepest level. Because our specific universe starts in a special state and hows a strong arrow of time, these emergent pictures can invoke words like “purpose” and “adaptation,” even though those ideas are nowhere to be found in the underlying mechanistic behavior of reality. (292-293)

There is no general principle along the lines of “new kinds of things cannot naturally arise in the course of undirected evolution.” Things like “stars” and “galaxies” come to be in a universe where they formerly didn’t exist. Why not purposes and information? (293)

The appearance of something like “purpose” simply comes down to the question “Is ‘purpose’ a useful concept when developing an effective theory of this part of reality in this particular domain of applicability?” (293)

There is no Platonic idea of a “want” floating out there in the space of ideas that an be properly associated with some kinds of beings and not with others. Rather, there are situations in which it is useful to describe things as somebody wanting something, and other situations in which that is not so useful. These situations can emerge in the natural, undirected evolution of matter in the universe. Those wants are as real as things ever get. (295)

Under naturalism, there isn’t that much different between a human being and a robot. We are all just complicated collections of matter moving in patterns, obeying impersonal laws of physics in an environment with an arrow of time. Wants and purposes and desires are the kinds of things that naturally develop along the way. (295)

Voynich manuscript.

The macroscopic information contained in a book is relative to the environment in which it is embedded. When we talk about the information contained in the book you are currently reading, what we mean is that these words are correlated with certain ideas that you get upon reading them. … The same holds for the information contained in a strand of DNA: it is correlated with the synthesis of certain proteins int he cell. It is this connection with one configuration of matter (a book or a DNA strand) and something else in the universe (the image of a giraffe, or a useful protein molecule) that lets us talk about the existence of information. Without those correlations–if there isn’t, and never will be, anyone around to read the book, or any RNA molecules that can read the DNA and go off to make protein–there is no point in talking about information. (297)

From this perspective, the appearance of information-bearing objects in the course of the undirected evolution of matter and life is unsurprising. (297)

As the universe evolves from this very specific configuration to increasingly generic ones, correlations between different parts of the universe develop very naturally. It becomes useful to say that one part carries information about another part. It’s just one of t e many helpful ways we have of talking about the world at an emergent, macroscopic level. (298)

Alvin Plantinga and Huston Smith’s open letter. Francis Collins. Kenneth Miller.

True, all of these seemingly miraculous occurrences would be allowed under the rules of quantum mechanics; they would simply be very unlikely. Very, extremely, outrageously unlikely. If we populated every planet circling eery star in the universe with scientists, and let them do experiments continuously for many times the current age of the observable universe, it would be extraordinarily improbable that even one of them would witness a single drop of water changing into wine. But it’s possible. (299)

Observing an event that is so extremely unlikely that you wouldn’t expect to see it anywhere in the observable universe should count as evidence that you are calculating probabilities in the wrong theory. (300)

If God micromanages which outcomes are realized in quantum events, it is just as much an intervention as if he were to alter the momentum of a planet in classical mechanics. God either does, or does not, affect what happens in the world. (300

The problem for theism is that there’s no evidence that he does. Advocates of theistic evolution do not make a positive case that we need divine intervention to explain the course of evolution; they merely offer up quantum mechanics as a justification that it could possibly happen. But of course it can possibly happen, if God exists; God can do whatever he wants, no matter what the laws of physics may be. What theistic evolutionists are actually doing is using quantum indeterminacy as a fig leaf: it’s not that God is allowed to act in the world, it’s that they are allowed to imagine him acting in a way such that nobody would notice, leaving no fingerprints. (300-301)

It is unclear why God would place such a high value on acting in ways that human beings can’t notice. This approach reduces theism to the case of the angel steering the moon, which we considered in chapter 10. you can’t disprove the theory by any possible experiment, since it is designed precisely to be indistinguishable from ordinary physical evolution. But it doesn’t gain you anything either. It makes the most sense to place our credence in the idea that the divine influences simply aren’t there. (301)

36. Are We the Point?

…fine-tuning is probably the most respectable argument in favor of theism. … The fine-tuning argument plays by the rules of how we come to learn about the world. (303)

It’s the best argument we have for God’s existence. (303) [via: Is it really?]

It’s still not a very good argument. It relies heavily on what statisticians call “old evidence”–we didn’t first formulate predictions of theism and naturalism and then go out and test them; we knew from the start that life exists. There is a selection effect: we can be having this conversation only in possible worlds where we exist, so our existence doesn’t really tell us anything new. (303)

First, we don’t have reliable ways of judging whether the values of various physical quantities are likely or unlikely. (304)

Second, we don’t know that much about whether life would be possible if the numbers of our universe were very different. (305)

…when it comes to most of the numbers characterizing physics and astronomy, it’s very hard to say what would happen were they to take on other values. (305)

Fred Adams. Fred Hoyle. Robert Forward, Dragon’s Egg.

There is another famous complication: we might not have just a universe, but a multiverse. (306)

Whether or not we live in a multiverse is a perfectly ordinary scientific consideration, to be judged by perfectly ordinary methods: what physical model provides the best account of the data? (307)

compactification. Alan Guth.

What we can say with confidence is that if we get a multiverse in this way, any worries about fine-tuning and the existence of life evaporate. Finding ourselves in a universe that is hospitable to life is no stranger, nor any more informative, than finding ourselves living on Earth: there are many different regions, and this is the one in which we can live. (309)

So what about the likelihood of a universe like ours appearing under theism? Here we are faced with a similar problem: the word “theism” doesn’t refer to a unique, predictive theory of the world. (309)

It’s reasonable to accept that theism predicts the existence of life with high probability. (309)

The requirement that our physical situation be compatible with complex networks of chemical reactions that perpetuate themselves and feed off of free energy in the way we usually associate with living organisms is only relevant if naturalism is true. If anything, the fact that our universe does allow for these physical configurations should be taken to increase our credence for naturalism at the expense of theism.

| Any theist worth their salt could, admittedly, come up with a number of reasons why God would choose to associate immaterial souls with complex self-sustaining chemical reactions, at least for a time. Likewise, if we lived in a universe where life was not associated with matter in such a way, it wouldn’t be hard to come up with justifications for that. This is the problem with theories that are not well defined. (310)

If one wants to claim that theism explains certain features of our universe because we predict that God would want life to exist, we must then ask what other features of the universe we would predict under theism. It is here that theism doesn’t fare so well. (311)

There are a number of features of the universe that we would probably expect to see if the existence of life (or human beings) was a primary consideration in its design. Let’s highlight three:

  1. Degree of fine-tuning. If the reason why certain characteristics of the universe seem fine-tuned is because life needs to exist, we would expect them to be sufficiently tuned to allow for life, but there’s no reason for them to be much more tuned than that.
  2. Messiness of observed physics. If the laws of physics were chosen so that life could exist, we would expect that each of the various features of those laws would play some important role in the unfolding of life. … Why did God make the top and bottom quarks, for example, and why do they have the masses they do? Under naturalism we would expect a variety of particles, some of which are important to life and some which are not. That’s exactly what we do observe.
  3. Centrality of life. If the eventual appearance of life were an important consideration for God when he was designing the universe, it is hard to understand why life seems so unimportant in the final product. … Theism predicts that most other stars and galaxies shouldn’t be there at all.

A theory gets credit for explaining features of the world only to the extent that it goes out on a limb and makes predictions for what the world should be like.

| A somewhat better response is to put forward some positive theory for why God would want the universe to look the way it does, in particular why it seems so wildly extravagant, with all of those stars and galaxies and whatnot. (313)

Our theories are inevitably influenced by what we already know about the world. To get a more fair view of what theism would naturally predict, we can simply look at what it did predict, before we made modern astronomical observations. The answer is: nothing like what we actually observe. (313)


37. Crawling into Consciousness

What you can see has a dramatic effect on how you think. (318)

See something, respond almost immediately. A fish brain is going to be optimized to do just that. Quick reaction, not leisurely contemplation, is the name of the game. (318)

When you can see what’s coming long before you are forced to react, you have the time to contemplate different possible actions, and weigh the pros and cons of each. You can even be ingenious, putting some of your cognitive resources into inventing plans of action other than those that are immediately obvious. (318)

Out in the clear air, it pays to use your imagination. (318)

Malcolm MacIverconsciousness.

Consciousness is not a single brain organ or even a single activity; it’s a complex interplay of many processes acting on multiple levels. It involves wakefulness, receiving and responding to sensory inputs, imagination, inner experience, and volition. (319)

What does it mean to be a self-conscious animal? The idea is ludicrous, if it is not monstrous. It means to know that one is food for worms. This is the terror: to have emerged from nothing, to have a name, consciousness of self, deep inner feelings, and excruciating inner yearning for life and self-expression–and with all this yet to die. – Ernest Becker, commenting on Danish philosopher Soren Kierkegaard

Is consciousness “just” a way of talking about the behavior of certain kinds of collections of atoms, obeying the laws of physics? Or is there something definitively new about it–either an entirely new kind of substance, as René Descartes would have had it, or at least a separate kind of property over and above the merely material? (319)

Our main goal here is not to explain how consciousness does work, but to illustrate that it can work in a world governed by impersonal laws of nature. (320)

Daniel Dennett. “Cartesian theater.”

Our minds are not run as top-down dictatorships; they are rambunctious parliaments, populated by squabbling factions and caucuses, with much more going on beneath the surface than our conscious awareness ever accesses. (320-321)

Daniel Kahneman.

Your consciousness is like a tiny stowaway on a transatlantic steamship, taking credit for the journey without acknowledging the massive engineering underfoot. – David Eagleman

The System1/System 2 distinction is an example of what’s known as dual process theory.

The hallmark of consciousness is an inner mental experience. … you know you exist. … It’s this reflexive property–the mind thinking about itself–that makes consciousness so special. (322)

Bruce Bridgeman.

There’s a lot going on beneath the deceptively simple idea of “making plans.” We have to have the ability to conceive of times in the future, not merely the present moment. We need to be able to represent the actions of both ourselves and the rest of the world in our mental pictures. We must reliably predict future actions and their likely responses. Finally, we must be able to do this for multiple scenarios simultaneously, and eventually compare and choose between them. (323)

Endel Tulving, chronesthesia, or “mental time travel.” semantic memory. episodic memory.

Mental time travel, Tulving suggested, is related to episodic memory: imagining the future is a similar conscious activity to recalling events in the past. (323)

38. The Babbling Brain

glial cells.

The connectome is simply the list of every single neuron in the brain, along with all the connections between them. (329)

Eric Kandel.

The connectome is a network, but it’s a hierarchical network. (331)

small-world network.

…phase transitions, since systems become critical right as they are about to change from one phase to another. (333)

A brain that is not critical is a brain that does exactly the same thing every minute, or, in the other extreme, is so chaotic that it does a completely random thing, no matter what the circumstances. That is the brain of an idiot. – Dante Chialvo

Capgras delusion.

39. What Thinks?

Robert A. Heinlein, The Moon Is a Harsh Mistress.

Alan Turing. John Searle.

If the world is purely physical, then what we mean by “understanding” is a way of talking about a particular kind of correlation between information located in one system (as instantiated in some particular arrangement of matter) and conditions in the external world. (340)

A human can be thought of as a configuration of several trillion cells. If the physical world is all there is, we have to think that consciousness results from the particular motions and interactions of all those cells, with one another, and with the outside world. (341)

Ned Block. Cynthia Breazeal.

40. The Hard Problem

Thomas Nagel.

…the mind-body problem: how can we hope to account for mental reality using only physical concepts? (349)

We’re pre-Newton, pre-Kepler. We’re still sussing out that there are moons around Jupiter. – Patricia Churchland

David Chalmers, Easy Problems and Hard Problems. Peter Hankins. Frank Jackson.

…the phrase “all the physical facts about color” conjures a certain vague impression in our minds, but it’s far from clear that this expression corresponds to any well-defined concept. (352)

Vagueness about physical facts isn’t the biggest problem with citing Mary as evidence for the existence of features of the universe that aren’t purely physical. The real issue is with slipperiness in the definitions of “knowledge” and “experience.” (352)

Is this an argument that there is more to the universe than its physical aspects? Surely not. We have merely introduced an artificial distinction between two kinds of collections of synaptic connections: “ones induced by reading literature and doing scientific experiments in black and white,” and “ones induced by stimulating the visual cortex by seeing red photons.” This is a possible way to carve up our knowledge of the universe, but not a necessary one. It’s a difference in the way the knowledge got to your brain, not in the kind of knowledge it is. This is not an argument that should induce us to start adding wholly new conceptual categories to our successful models of the natural world. (353)

41. Zombies and Stories

The possible existence of zombies hinges on the idea that one can be a naturalist but not a physicalist–we can accept that there is only the natural world, but believe that there is more to it than its physical properties. (355)

According to poetic naturalism, philosophical zombies are simply inconceivable, because “consciousness” is a particular way of talking about the behavior of certain physical systems. (358)

…”water without oxygen” is not conceivable. (358)

Likewise, if you think that conscious experience is something truly distinct from the physical behavior of matter, you should have no trouble imagining zombies; but if consciousness is just a concept we use to describe certain physical behaviors, zombies become inconceivable. (359)

The idea that our mental experiences or qualia are not actually separate things, but instead are useful parts of certain stories we tell about ordinary physical things, is one that many people find hard to swallow. (359)

Individual atoms don’t have experiences, but macroscopic agglomerations of them might very well, without invoking any additional ingredients. (360)

Poetic naturalism is “poetic” because there are different stories we can tell about the world, many of them capturing some aspects of reality, and all useful in their appropriate context. (362)

42. Are Photons Conscious?

If consciousness were something over and above the physical properties of matter, there would be a puzzle: what was it doing for all those billions of years before life came along? | Poetic naturalists have no problem with this question. The appearance of consciousness is a phase transition, like water boiling. (363)

panpsychism. David Chalmers. Giulio Tononi. Christof Koch. Roger Penrose. Gödel’s Incompleteness Theorem. Kurt Gödel.

If we want a machine to be intelligent, it can’t also be infallible. There are theorems that say almost exactly that. – Alan Turing

43. What Acts on What?

If it isn’t literally true that my wanting is causally responsible for my reaching, and my itching is casually responsible for my scratching, and my believing is causally responsible for my saying…if none of that is literally true, then practically everything I believe about anything is false and it’s the end of the world. – Jerry Fodor

Don’t worry! We live in a reality that can be fruitfully talked about in many different ways. We have an extravagant assortment of theories, models, vocabularies, stories, whatever you prefer to call them. When we speak about a human being, we can describe them as a person with desires and tendencies and inner mental states; or we can describe them as a collection of biological cells interacting via electrochemical signals; or we can describe them as an agglomeration of elementary particles following the rules of the Core Theory. The question is, how do we fit these different stories together? In particular, what acts on what? Does the existence of the particle-physics description, in which “causality” is nowhere to be found, imply that it is illegitimate to talk about scratching being caused by itching?

| The poetic-naturalist answer is that any of the stories we have stands or falls on its own terms as a description of reality. To evaluate a model of the world, the questions we need to ask include “Is it internally consistent?,” “Is it well-defined?,” and “Does it fit the data?” … The success of one theory doesn’t mean that another one is wrong; that only happens when a theory turns out to be internally incoherent, or when it does a bad job at describing the observed phenomena. (373)

Developing a theory of human thought and behavior in terms of neural signals or interacting particles doesn’t in any way imply that your wanting is not responsible for your reaching. There is no obstacle to that kind of vocabulary of desire and intentionality being “true,” as long as its predictions are compatible with those of other successful vocabularies. (373)

This issue seems more complicated than it is because of an understandable tendency, in a world described by multiple distinct but mutually compatible stories, to jumble up the concepts of one story with those of another–to cross the lines separating distinct ways of talking. (374)

[via: I call this a “discipline breach.”]

downward causation: behavior of the parts is actually caused by a the state of the whole, in a way not interpretable as due to the parts themselves. (375)

Thinking of behavior in one theory as causing behavior in a completely different theory is the first step toward a morass of confusion from which it is difficult to extract ourselves. (375)

44. Freedom to Choose

Do I, at the end of the day, have free will? | THere’s a sense in which you do have free will. There’s also a sense in which you don’t. Which sense is the “right” one is an issue you’re welcome to decide for yourself (if you think you have the ability to make decisions). (378)

The concept of choice does exist, and it would be difficult indeed to describe human beings without it. … But it is artificial and counterproductive to deny ourselves the vocabulary of choice when we talk about human beings, regardless of how well we understand the laws of physics. This stance is known in the philosophical literature as compatibilism, and refers to the compatibility between an underlying deterministic (or at least impersonal) scientific description and a macroscopic vocabulary of choice and volition. Compatibilism, which traces its roots back as far as John Locke in the seventeenth century, is the most popular way of thinking about free will among professional philosophers. (379)

Once you frame the question in terms of you and your choice, you can’t also start talking about your atoms and the laws of physics. Either vocabulary is perfectly legitimate, but mixing them leads to nonsense. (379)

The small differences in a person’s brain state that correlate with different bodily actions typically have negligible correlations with the past state of the universe, but they can be correlated with substantially different future evolutions. That’s why our best human-sized conception of the world treats the past and future so differently. We remember the past, and our choices affect the future. (380)

One popular definition of free will is “the ability to have acted differently.” In a world governed by impersonal laws, one can argue that there is no such ability. Given the quantum state of the elementary particles that make up me and my environment, the future is governed by the laws of physics. But in the real world, we are not given that quantum state. We have incomplete information; we know about the rough configuration of our bodies and we have some idea of our mental states. Given only that incomplete information–the information we actually have–it’s completely conceivable that we could have acted differently. (380-381)

Benjamin Libet.

If our belief in free will is predicated on the idea that “agents making choices” is part of the best theory we have of human behavior, then the existence of a better and more predictive understanding could undermine that belief. To the extent that neuroscience becomes better and better at predicting what we will do without reference to our personal volition, it will be less and less appropriate to treat people as freely acting agents. Predestination will become part of our real world.

| It doesn’t seem likely, however. … This is a subject in which the basics are far from settled, and much of the important science has yet to be established. What seems clear is that we should base our ideas about personal responsibility on the best possible understanding of how the brain works that we can possibly achieve, and be willing to update those ideas whenever the data call for it. (384)


45. Three Billion Heartbeats

Carl Sagan. Geoffrey West.

Three billion isn’t such a big number. What are you going to do with your heartbeats? (389)

…the search for meaning is not another kind of science. In science we want to describe the world as efficiently and accurately as possible. The quest for a good life isn’t like that: it’s about evaluating the world, passing judgment on the way things are and could be. We want to be able to point to different possible events and say, “That’s a worthy goal to strive for,” or “That’s the way we ought to behave.” Science couldn’t care less about such judgments. | The source of these values isn’t the outside world; it’s inside us. (389)

Poetic naturalism offers no such escape from the demands of meeting life in a creative and individual way. It is about you: it’s up to you, me, and every other person to create meaning and purpose for ourselves. This can be a scary prospect, not to mention exhausting. We can decide that what we want is to devote ourselves to something larger–but that decision comes from us. (390)

We’re Wile E. Coyote, and we’ve just looked down. (390)

There are two legitimate worries about the idea that we construct meaning for our lives. | The first worry is that it’s cheating. Maybe we are fooling ourselves if we think we can find fulfillment once we accept that we are part of the physical world, patterns of elementary particles beholden to the laws of physics. (390-391)

Water doesn’t stop being wet when you learn it’s a compound of hydrogen and oxygen. | The same goes for purpose, meaning, and our sense of right and wrong. If you are moved to help those less fortunate than you, it doesn’t matter whether you are motivated by a belief that it’s God’s will, or by a personal conviction that it’s the right thing to do. Your values are no less real either way. (391)

The second worry about creating meaning within ourselves is that there isn’t any place to start. If neither God nor the universe is going to help us attache significance to our actions, the whole project seems suspiciously arbitrary.

| But we do have a starting place: who we are. As living, thinking organisms, we are creatures of motion and motivation. At a basic, biological level, we are defined not by the atoms that make us up but by the dynamic patterns we trace out as we move through the world. (391)

In human terms, the dynamic nature of life manifests itself as desire. (392)

Desire is an aspect of caring: about ourselves, about other people, about what happens to the world. (392(

We are star stuff, which has taken its destiny into its own hands. – Carl Sagan

46. What Is and What Ought to Be

…talking about “oughts” is an entirely different kind of thing from simply talking about what “is.” The former is passing a judgment, saying what should be the case; the latter is merely descriptive, saying what actually happens. If you’re going to perform such a magic trick and call it philosophy, you should at least have the consideration to tell us how the trick is done. Modern thought has distilled the point down to a maxim: “you can’t derive ought from is.” (395)

An argument is said to be valid if the conclusion follows logically from the premises. In contrast, an argument is said to be sound if the conclusion follows from the premises and the premises themselves are true–a much higher standard to achieve. (396)

That’s the problem with attempting to derive ought from is: it’s logically impossible. If someone tells you they have derived ought from is, it’s like someone telling you that they’ve added together two even numbers and obtained an odd number. You don’t have to check their math to know that they’ve made a mistake. (397)

The reason why deriving ought from is should be thought of as a philosophical felony, rather than a simple misdemeanor, is because these hidden premises deserve our closest scrutiny. They are, more often than not, where most of the action is. (399)

  • The universe is expanding.
  • Humans and chimpanzees share a common ancestor.
  • We should work to allow people to lead happier and longer lives.

All of these statements are, by some lights, true. But only the first two are “scientific.” The reason is that each of them could have been false. (401)

The lack of an ultimate objective scientific grounding for morality can be worrisome. It implies that people with whom we have moral disagreements–whether it’s Hitler, the Taliban, or schoolyard bullies who beat up smaller children–aren’t wrong in the same sense that it’s wrong to deny Darwinian evolution or the expansion of the universe. We can’t do an experiment, or point to data, or construct a syllogism, or write a stinging blog post, that would persuade them of why their actions are bad. And if that’s true, why should they ever stop?

| But that’s how the world is. We should recognize that our desire for an objective grounding for morality creates a cognitive bias, and should compensate by being especially skeptical of any claims in that direction. (402)

47. Rules and Consequences

…what do we do when something that seems utterly wrong at a visceral level (killing your own son) runs into a foundational rule to which you are devoted (obeying God’s word)? When it is not clear what is right and wrong, what are the most basic principles that should ultimately decide? (404)

trolley problem. Philippa Foot.

Moral quandaries are real, even if they are usually not as stark as the trolley problem. How much of our income should we spend on our own pleasure, versus putting it toward helping the less fortunate? What are the best rules governing marriage, abortion, and gender identity? How do we balance the goal of freedom against that of security?

| As Abraham learned, having an absolute moral standard such as God can be extraordinarily challenging. But without God, there is no such standard, and that is challenging in its own way. The dilemmas are still there, and we have to figure out a way to face them. Nature alone is no help, as we can’t extract ought from is; the universe doesn’t pass moral judgments.

| And yet we must live and act. We are collections of vibrating quantum fields, held together in persistent patterns by feeding off of ambient free energy according to impersonal and uncaring laws of nature, and we are also human beings who make choices and care about what happens to ourselves and to others. What’s the best way to think about how we should live? (405)

Philosophers find it useful to distinguish between ethics and meta-ethics. … Meta-ethics takes a step back, and asks what it means to say something is right or wrong, and why we should adopt one set of guidelines rather than some other set. “Our system of ethics should be based o improving the well-being of conscious creatures” is a meta-ethical claim, from which “killing puppies is wrong” might be derived.

| Poetic naturalism has little to say about ethics, other than perhaps for a few inspirational remarks. But it does have something to say about meta-ethics, namely: our ethical systems are things that are constructed by us human beings, not discovered out there in the world, and should be evaluated accordingly. (405-406)


Our minds have a System 1 that is built on heuristics, instincts, and visceral reactions, as well as a System 2 that is responsible for cognition and higher-level thoughts. Roughly speaking, System 1 tends to be responsible for our deontological impulses, and System 2 kicks in when we start thinking as consequentialists. In the words of psychologist Joshua Greene, we not only have “thinking fast and slow”; we also have “morality fast and slow.” System 2 thinks we should pull the switch, while System 1 is appalled by the idea. (406)

Judith Jarvis Thomsonvirtue ethics.

If deontology is about what you do, and consequentialism is about what happens, virtue ethics is about who you are. (408)

Frans de Waal. Sarah Brosnan.

One approach to moral philosophy is to think of it as simply a method for making sense of those commitments: making sure that we are true to our own self-proclaimed morals, that our justifications for our actions are internally consistent, and that we take into account the values of other people where appropriate. Rather than fitting data in a scientific sense, we can choose our ethical theories by how well they conform to our own existing sentiments. A moral framework is “useful” to a poetic naturalist to the extent that it reflects and systematizes our moral commitments in a logically coherent way. (409)

We have a feeling for what distinguishes right from wrong, and we try to make it systematic. We talk to other people to learn how they feel, and take that into account when developing the rules for functioning in society. (409)

You’re telling me that judging right from wrong is just a matter of our personal feelings and preferences, grounded in nothing more substantial than our own views, with nothing external to back it up? That there are no objectively true moral facts out there in the world?

| Yes. But admitting that morality is constructed, rather than found lying on the street, doesn’t mean that there is no such thing as morality. All hell has not broken loose. (410)

moral constructivism … is a bit different from “relativism.” (410)

A moral constructivist, by contrast, acknowledges that morality originates in individuals and societies, but accepts that those individuals and societies will treat the resulting set of beliefs as “right,” and will judge others accordingly. Moral constructivists have no qualms about telling other people that they’re doing the wrong thing. Furthermore, the fact that morals are constructed doesn’t mean that they are arbitrary. Ethical systems are invented by human beings, but we can all have productive conversations about how they could be improved, just as we do with all sorts of things that human beings put together. (410)

Sharon Streetcategorial imperative: act in such a way that your actions could become a universal law. (411)

A Kantian constructivist accepts that morality is constructed by human beings, but believes that every rational person would construct the same moral framework, if only they thought about it clearly enough. A Humean constructivist takes one more step: morality is constructed, and different people might very well construct different moral frameworks for themselves. (411)

Hume was right. We have no objective guidance on how to distinguish right from wrong: not from God, not from nature, not from the pure force of reason itself. Alive in the world, individual and contingent, we are burdened and blessed with all of the talents and inclinations and instincts that evolution and our upbringings have bequeathed to us. Those are the raw materials from which morals are constructed. Judging what is good and what is not is a quintessentially human act, and we need to face up to that reality. Morality exists only insofar as we make it so, and other people might not pass judgments in the same way that we do. (411)

48. Constructing Goodness

utilitarianism. Derek Parfit. Robert Nozick.

The basic issue remains: the notion of attaching a single value of “utility” to every action, and working to increase it, is a hard one to pull off in practice. (413)

Thalia Wheatley and Jonathan Haidt.

Poetic naturalism refuses to offer us the consolation of objective moral certainty. There is no “right” answer to the trolley problem. How you should act depends on who you are. (415)

Ay, there’s the rub. We want there to be objective solutions to our dilemmas, as surely as there are theorems in mathematics or experimental discoveries in science. (415)


Think of these things, too, in the light of the brevity of any punishment you can inflict—never to last longer than till death. On this ground Epicurus makes light of all suffering and pain, maintaining that if it is small, it is contemptible; and if it is great, it is not long-continued.  No doubt about it, we, who receive our awards under the judgment of an all-seeing God, and who look forward to eternal punishment from Him for sin,—we alone make real effort to attain a blameless life. (from Chapter XLV)

…if we were to accept that morality is constructed, individuals will run around giving into their worst instincts, and we would have no basis on which to condemn obviously bad things like the Holocaust. (416)

The constructivist answers that just because moral rules are invented by human beings, that doesn’t make them any less real. (416)

James Naismith.

It’s not clear what operational benefit would be gained by establishing morality as an objective set of facts. (417)

Moral progress is possible because most people share many moral sentiments; if they don’t reasoning with them wouldn’t help much no matter what. (417)

If, upon rational reflection, we decide that something is deeply wrong, there is no reason why we cannot work to prevent it from happening, regardless of whether our decision is based on external criteria or our own inner convictions. Again, this is no more or less than what really happens in the world.

| Deciding how to be good isn’t like solving a math puzzle, or discovering a new fossil. It’s like going out to dinner with a group of friends. We think about what we want for our individual selves, talk to others about their desires and how we can work together, and reason about how to make it happen. The group may include both vegetarians and omnivores, but with a good-faith effort there’s no reason everyone can’t be satisfied. (417)

Poetic naturalism doesn’t tell us how to behave, but it warns us away from the false complacency associated with the conviction that our morals are objectively the best. Our lives are changing in unpredictable ways; we need to be able to make judgments with clear eyes and an accurate picture of how the world operates. We don’t need an immovable place to stand; we need to make our peace with a universe that doesn’t care what we do, and take pride in the fact that we care anyway. (418)

49. Listening to the World

Ten Coniderations: a list of things we think are true, that might be useful to keep in mind as we shape and experience our own ways of valuing and caring about our lives.

1. Life Isn’t Forever.

You don’t really want to live forever. Eternity is longer than you think. (420)

2. Desire Is Built into Life.

3. What Matters Is What Matters to People.

4. We Can Always Do Better.

Progress comes, not from new discoveries in an imaginary science of morality, but from being more honest and rigorous with ourselves–from uncovering our rationalizations and justifications for behavior that, if we admit it, was pretty reprehensible from the start. (422-423)

5. It Pays to Listen.

There’s no reason to throw out everything associated with the great thinkers of the past just because we have a more updated and accurate ontology. … We can take inspiration from ancient teachings, not to mention from great literature and art, without being bound by them. (423)

6. There Is No Natural Way to Be.

We have inclinations and desires, partly born of our innate dispositions, but we also have the opportunity to change, as individuals and as a society. (424)

7. It Takes All Kinds.

If our lives are to have meaning and purpose, we are going to have to create them. And people are different, so they’re going to create different things. That’s a feature to be celebrated, not an annoyance to be eradicated. (424)

Poetic naturalism doesn’t provide much comfort for those who take joy in telling other people the proper way to live their lives. It allows for pluralism in purpose and meaning, a rich ecosystem of virtues and lives well lived. (425)

8. The Universe Is in Our Hands.

Our ability to think has given us enormous leverage over the world around us. We won’t be able to stave off the heat death of the universe, but we can alter bodies, transform our planet, and someday spread life through the galaxy. It’s up to us to make wise choices and shape the world to be a better place. (425)

9. We Can Do Better Than Happiness.

Scholars who study meaning in life distinguish between synchronic meaning and diachronic meaning. Synchronic meaning depends on your state of being at any one moment in time: you are happy because you are out in the sunshine. Diachronic meaning depends on the journey you are on: you are happy because you are making progress toward a college degree. If we permit ourselves to take inspiration from what we have learned about ontology, it might suggest that we focus more on diachronic meaning and the expense of synchronic. (426)

At the end of the day, or the end of your life, it doesn’t matter so much that you were happy much of the time. Wouldn’t you rather have a good story to tell? (426)

10. Reality Guides Us.

Shelley Taylor and Jonathon Brown. “positive illusions“.

When we want something to be true, when a belief makes us happy–that’s precisely when we should be questioning. Illusions can be pleasant, but the rewards of truth are enormously greater. (427)

50. Existential Therapy

I am in awe of the universe: its scope, its complexity, its depth, its meticulous precision. But my primary feeling is wonder. Awe has connotations of reverence: “this fills me with awe and I am not worthy.” Wonder has connotations of curiosity: “this fills me with wonder and I am going to figure it out.” I will take wonder over awe every day. (430)

Everything we’ve experienced about the universe suggests that it is intelligible: if we try hard enough we can come to understand it. (430)

Thinking like this eventually led me to abandon my belief in God and become a cheerful naturalist. But I hope I never make the mistake of treating people who disagree with me about the fundamental nature of reality as my enemies. The important distinction is not between theists and naturalists; it’s between people who care enough about the universe to make a good-faith effort to understand it, and those who fit into a predetermined box or simply take it for granted. The universe is much bigger than you or me, and the quest to figure it out unites people with a spectrum of substantive beliefs. It’s us against the mysteries of the universe; if we are about understanding, we’re on the same side. (430)

Albert Camus. “The Myth of Sisyphus.”

Three billion heartbeats. The clock is ticking. (433)

Critical Review

There are two areas of personal reflection that must be recognized as having influenced my critical review.

First, throughout my life, apologetics has provided me a wide set of tools [i.e., arguments] to bolster and buttress my theological premises. If I’m honest, it is both disheartening and thrilling to have in one volume a near demolition of most of those tools. This is not to say that I’ve become “convinced/persuaded” toward any new premise, but it is to say that the entire endeavor of defending the “truth” of God has become, for me, passé. Heck, the endeavor of “defending” anything has worn on my soul.

There’s something psychologically important about that recognition [concession (?)]. To “defend” anything changes something in the posture of the mind. To engage in logic, reason, or any argumentation if one is defending a premise has the effect of clouding one’s rational faculties because the primitive urge to “save face” is so strong, it can [almost always does (?)] keep one from seeing clearly. Put simply, it’s always best to keep an “open mind.” To do so, one must stop having a “defensive mind.” Perhaps this is why the human categories of “immaturity” and “pride” are inextricable linked.

(By the way, “defending” is not the same thing as “arguing,” which is what Carroll does a lot of in his book. I support really good arguments. I am withdrawing from the emotional and intellectual posture of defending.)

So, while disheartened at the realization that much of my life has been spent pontificating irrelevancies and fallacies (ha!), that despondency is quickly eradicated by the thrill of discovery, and the awareness of deeper and more profound truths about this universe.

Second, there is a theological stream of thought that continues to persist because it’s very foundation lay, not in any argument for “God’s existence,” or “God’s necessity,” but in the embrace of a belief about God that is not contingent upon “argument.” This is found in two main expressions. One, that “God” is a personal belief established through one’s experience with the divine. Second that “God” is discovered more through everything that can be uncovered about this universe. Whatever is learned about this universe is additional information about God that I didn’t previously understand before. (“Ah, so, God is not the ’cause’ of the universe! Fascinating!”) As such, reading The Big Picture only adds to the substance of that belief, even if, within its pages is a really well argued explanation for “naturalism” over “theism.”

Last, Carroll does a phenomenal job at showing the importance and primacy of epistemology in our intellectual endeavors. Unlike other quite popular scientists who have publicly disdained philosophy, Carroll not only realizes its importance, but has a developed a professional proficiency that truly marshals a respectable intellectual integrity, one that I hope all would embrace.

With that, here are some reflections that I offer in that same vein and spirit.

Is “naturalism” “natural?”

It seems that throughout the scope of human history (see Sapiens), some rendition of theology has been the default or “natural” way in which people have sought to explain their observations about the universe. (I recognize that I’m using the word “natural” here with a different connotation). It seems reasonable to suggest that just as our biology has evolved, so has our consciousness, and thus our epistemology. But it certainly feels as if some iteration of supernaturalism will be with us, for a long, long time, as I wonder if it is embedded within the very “fabric of our being.” While Carroll states that a unified theory may “go all the way,” and that it is a big deal that, “we will ultimately understand the world as a single, unified reality, not caused or sustained or influenced by anything outside itself,” I simply wonder if our species will ever truly embrace that explanation in toto. At least thus far, it certainly doesn’t seem natural for humans to see the world in that way.

Baysian abduction vs. primitive intuition?

On page 80 and following, Carroll explains quite articulately the way in which our abductive reasoning should work. The problem is that as Jonathan Haidt and others have argued, “intuition comes first.” So, while the philosophy may be rationally sound, is it robust enough to usurp that primal neurology? Words like “evidence” and “data” are, and continue to be, misinterpreted and maligned to such a degree that it feels even more challenging to know what we’re talking about at all in some conversations. In other words, while a robust epistemology may be the right approach to truth seeking, practically, upon what foundation does epistemology itself stand upon when we are governed ultimately by our intuitions, and our desires? (Again, I’m referring to the scope of The Righteous Mind).

God is not a “theory.”

On pages 81-82 Carroll writes,

Consider two theories: theism (God exists) and atheism (God doesn’t exist). And imagine we lived in a world where the religious texts from different societies across the globe and throughout history were all perfectly compatible with one another–they all told essentially the same stories and promulgated consistent doctrine, even though there was no way for the authors of those texts to have ever communicated. Everyone would, sensibly, count that as evidence in favor of theism. You could cook up some convoluted explanation for the widespread consistency even under atheism: maybe there is a universal drive toward telling certain kinds of stories, implanted in us by our evolutionary history. But we can’t deny that theism provides a more straightforward explanation: God spread his word to many different sets of people. (81-82)

I see several things wrong with this. First, Carroll presumes a specified way in which God would or would not “communicate,” that is, if God communicates at all. How does Carroll know that God’s existence would result in “essentially the same stories,” and “consistent doctrine?” This assumption of uniformity may be a misstep on several levels. One, if uniformity is the way in which God communicates, and Carroll,, are searching for the “unified theory” that explains everything, perhaps the entire endeavor is itself a search for “God.” Two, when it comes to “explanations of the universe,” Carroll himself has demonstrated that there are various ways of speaking about the universe that are perhaps “useful” at various levels. Could not the same be true of theology? Perhaps, a variety of people could speak of the divine in a variety of disparate ways, contradictorily and paradoxically, that are not necessarily false? Three, many religious philosophers would posit that while distinctly different at the details level, at the higher levels, most religions at their core speak to a consistent stream of human understanding. If there is an argument regarding the differences of “doctrine,” then there is also an argument on the similarities of substance.

Second, as mentioned above, this argument presumes God to be somehow governed (and therefore argued) in the same epistemological category, that God is somehow a “theory” to be understood within the scope of the universe. Perhaps, this “discipline breach” is what dooms any “argument” about “God” in the first place, rendering any argument for God null and void. (See, perhaps John Caputo, or John A.T. Robinson).

Is an experience with the divine empirically true?

On page 133 Carroll writes,

Science isn’t characterized by methodological naturalism but by methodological empiricism–the idea that knowledge is derived from our experience of the world, rather than by thought alone. Science is a technique, not a set of conclusions. (133)

Is not our [collective human] metaphysical experience with the divine part of this “knowledge?” I’m not merely asking, “Is it empirically true that people have supernatural experiences?” I’m asking, “Does phenomenology itself have any explanatory power? Can experiences, even when ‘explained’ by neuroscience increase the credence for supernaturalism?” Perhaps I’m also arguing whether or not scientific observation is the same thing as explanation.

The problem of the “category” of evil.

On pages 146 and 147 Carroll tackles the “problem of evil. On page 148 he writes,

One could try to avoid the problem [of evil] by denying that theism makes any predictions at all for what the world should be like–God’s essence is mysterious and impenetrable to our minds. That doesn’t solve the problem–as long as atheism does make predictions, evidence can still accumulate one way or the other–but it does not ameliorate it somewhat. Only at a significant cost, however: if ontology predicts almost nothing, it ends up explaining almost nothing, and there’s no reason to believe it. (148)

A couple things here. First, Carroll does not seem to clarify or substantiate any definition of “evil” in his argument. Admittedly, this would add several pages to his already robust book, however it needs to be noted that “evil” itself as a category is not a physical, therefore “natural” entity. One can only talk about “evil” in transcendent terms. “Evil” is, itself, a philosophical/theological category. Many would argue that to concede the existence of evil is to concede the existence of the transcendent. As Carroll himself has suggested, there are some ways in which we talk about the universe that are “useful,” but not necessarily “real.” I would suggest that his line of argument on evil, therefore, has no foundation, based upon his very own definitions and categories. If evil is not “real,” but only “useful,” then we can only talk about it as an emergent property of the universe, not as a theory for it.

Second, his statement about ontology is incoherent. I would refer to Stanford’s online Encyclopedia of Philosophy for further explanation, but in summary, ontology helps us understand not only if things exist, but the relationships and characteristics of things that do exist. It can also help us form methodologies about things that have an ambiguous existence (such as numbers). Applied to the specific example above, “ontology predicts almost nothing” because ontology is not a predictive category. It’s more of a “conclusive” category that can work backward.

Theism is not an explanation.

One of the most summative poignant parts of his book is on page 204.

The theistic side of the argument would be must stronger if it extended beyond “God would have wanted a hospitable universe to exist, and here we are” to specific aspects of the physical world, especially ones we haven’t yet discovered. If you want to claim that the properties of our kind of universe provide evidence for God’s existence, you need to believe that you understand God’s motivations well enough to say that it’s more likely God would have created this kind of universe rather than some other kind. And if that’s true, it’s natural to ask for even more. How many galaxies would God have wanted to create? What would God have made the dark matter consist of? … What we can’t do is demand explanations that the universe may not be able give us [sic]. (204)

It is this last line that ultimately drives the ethics of Carroll’s inquiry. And as long as theistic categories are argued within the physical and explanatory scope of this universe, they are subject to the rules, boundaries, and critiques of the physical sciences. While mainstream theology and popular Christian apologetics have missed this memo, theologians throughout history have noted this point, all the way back to Augustine. I admit that their arguments have fallen short of post-Enlightenment coherence, but it is simply to say that minor strands of theological thought have conceded this point, and attempted to provide a theological construct that is as transcendent as its claims.

Is the methodological process equal to a philosophical premise?

Here, I repeat the quote from the notes above from page 270,

There is no reason to think that we won’t be able to figure out how life started. No serious scientist working on the origin of life, even those who are personally religious, points to some particular process and says, “here is the step where we need to invoke the presence of a nonphysical life-force, or some element of supernatural intervention.” There is a strong conviction that understanding abiogenesis is a matter of solving puzzles within the known laws of nature, not calling for help from outside of them. (270)

I concur that anytime we attempt to invoke “God” into the argument, we are slipping into the “god-of-the-gaps” argument. I am persuaded more and more that almost all apologetic arguments for God’s existence is some form of this line of thinking. However, unlike Carroll’s philosophical humility expressed throughout the rest of his book, this paragraph seems to presuppose naturalism [materialism (?)], positing a philosophical premise out of the methodological process. True, “understanding abiogenesis is a matter of solving puzzles within the known laws of nature.” However, it is untrue that we therefore conclude that there is no “help from outside of them.” The tools we use limit our philosophical conclusions, do they not?

What if theism predicts existence?

Carroll spends time discussing the predictive power of theism and writes on page 312,

A theory gets credit for explaining features of the world only to the extent that it goes out on a limb and makes predictions for what the world should be like.

What if “theism predicts existence?” What if “theism predicts that the universe is ordered, and can be discovered and understood?” (Both of these derived from Genesis 1 and general theology?) Would that give credence to theism? Unlike the “same doctrines and stories” line of argumentation above, this line of thinking considers what theism would actually predict, based upon theism’s own terms. Admittedly, not all theologies adhere to this kind of concepts, but that is simply to say that “not all theologies are created equal,” not that “theism is therefore discredited.”

Contrarily, what if theism makes no predictions? What if theism is not in the prediction business? If that is the case, then the entire program of discrediting theism is rendered null and void, accordingly.

Is God a “phase transition?”

On page 363, Carroll writes,

If consciousness were something over and above the physical properties of matter, there would be a puzzle: what was it doing for all those billions of years before life came along? | Poetic naturalists have no problem with this question. The appearance of consciousness is a phase transition, like water boiling. (363)

This is perhaps the great challenge for those who are deeply spiritual and adhere to faith in the transcendent, and who are intellectually scientific, committed to the truth of our universe, no matter what we discover. I can offer no definitive reply here. I can only say that in our current understanding, the realms of explanatory possibilities regarding God and the universe are expanding rapidly, and at a greater pace.

Without arrogant prognostication, I foresee a widely enveloping transcendence that encapsulates us all, or theological entropic heat death. Either way, I suppose, it’s in the hands of God.

Thank you, Sean Carroll.

A phenomenal read. I commend it to anyone and everyone who is attempting to understand The Big Picture of our universe.