The Big Picture
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chairs and universities and legal codes are real— in the sense that they play
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an essential role in a successful description of a certain part of the natural
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world, within a certain domain of applicability.
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It might seem strange that the logical possibility of a concept depends
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on whether this or that ontology turns out to be true, but we can’t decide
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whether “humanlike beings without consciousness” is a sensible concept
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until we know what consciousness is.
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In 1774, British clergyman Joseph Priestley isolated the element of oxy-
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gen. If you asked him whether he could imagine water without any oxygen,
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he presumably would have had no problem, since he didn’t know that water
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is made of molecules with one oxygen atom and two hydrogens. (Water was
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first decomposed into hydrogen and oxygen in 1800.) But now we know
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better, and realize that “water without oxygen” is not conceivable. In some
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possible world with somewhat different laws of physics, there may be an-
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other substance that is not H O, yet has all the phenomenological proper-
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ties of water— liquid at room temperature, transparent to visible light, and
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so on. But it wouldn’t be the water that we know and love. Likewise, if you
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think that conscious experience is something truly distinct from the phys-
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ical behavior of matter, you should have no trouble imagining zombies; but
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if consciousness is just a concept we use to describe certain physical behav-
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iors, zombies become inconceivable.
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The idea that our mental experiences or qualia are not actually separate
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things, but instead are useful parts of certain stories we tell about ordinary 12
physical things, is one that many people find hard to swallow.
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Even with the best of intentions on both sides, a dialogue between a
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property dualist who believes in the separate reality of mental properties
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(call him M) and a poetic naturalist who believes they are just ways of talk-
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ing about physical states (call her P) can be frustrating. It might go some-
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thing like this:
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M: I grant you that, when I am feeling some particular sensation,
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it is inevitably accompanied by some particular thing happen-
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ing in my brain— a “neural correlate of consciousness.” What
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I deny is that one of my subjective experiences simply is such
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an occurrence in my brain. There’s more to it than that. I also
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have a feeling of what it is like to have that experience.
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P: What I’m suggesting is that the statement “I have a feeling . . .”
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is part of an emergent way of talking about those signals ap-
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pearing in your brain. There is one way of talking that speaks
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in a vocabulary of neurons and synapses and so forth, and an-
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other way that speaks of people and their experiences. And
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there is a map between these ways: when the neurons do a cer-
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tain thing, the person feels a certain way. And that’s all there is.
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M: Except that it’s manifestly not all there is! Because if it were, I
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wouldn’t have any conscious experiences at all. Atoms don’t
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have experiences. You can give a functional explanation of
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what’s going on, which will correctly account for how I actu-
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ally behave, but such an explanation will always leave out the
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subjective aspect.
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P: Why? I’m not “leaving out” the subjective aspect, I’m suggest-
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ing that all of this talk of our inner experiences is a useful way
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of bundling up the collective behavior of a complex collection
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of atoms. Individual atoms don’t have experiences, but macro-
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scopic agglomerations of them might very well, without invok-
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ing any additional ingredients.
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M: No, they won’t. No matter how many non- feeling atoms you
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pile together, they will never start having experiences.
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P: Yes, they will.
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M: No, they won’t.
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P: Yes, they will.
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And you can imagine how it continues from there.
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Nevertheless, let’s make one more good- faith effort to explain to an
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open- minded property dualist how a poetic naturalist thinks about qualia.
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What do we mean when we say “I am experiencing the redness of red”? We
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mean something like this:
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There is a part of the universe I choose to call “me,” a collec-
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tion of atoms interacting and evolving in certain ways. I attri-
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bute to “myself” a number of properties, some straightforwardly
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physical, and others inward and mental. There are certain pro-
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cesses that can transpire within the neurons and synapses of my
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brain, such that when they occur I say, “I am experiencing red-
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ness.” This is a useful thing to say, since it correlates in predict-
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able ways with other features of the universe. For example, a
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person who knows I am having that experience might reliably
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infer the existence of red- wavelength photons entering my eyes,
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and perhaps some object emitting or reflecting them. They
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could also ask me further questions such as “What shade of red
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are you seeing?” and expect a certain spectrum of sensible an-
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swers. There may also be correlations with other inner mental
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states, such as “seeing red always makes me feel melancholy.”
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Because of the coherence and reliability of these correlations, I
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judge the concept of “seeing red” to be one that plays a useful
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role in my way of talking about the universe as described on hu-
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man scales. Therefore the “experience of redness” is a real thing.
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It’s a mouthful, and nobody would ever mistake it for a Shakespearean
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sonnet. But there’s a kind of poetry there, if you look closely enough.
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There are two points of view relevant to consciousness that are close cousins
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of poetic naturalism, but different in important ways.
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One view is to argue that all of these so-called qualia or inner experi-
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ences simply don’t exist— they are illusions. Maybe you thought you had
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inner experiences, but that is an antiquated part of our intuitive view of the
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world, a relic of a prescientific age. Now we know better, and should use a
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more updated and appropriate set of concepts.
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The other perspective is a strong form of reductionism that insists that
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subjective experiences simply are physical processes happening in the brain.
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They exist, but they can be identified with specific neural correlates. A fa-
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mous example along these lines comes from philosopher Hilary Putnam,
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who contemplated— to refute the idea, not to defend it— the position that
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“pain” is to be literally identified with “the firing of C-fibers.” (C-fibers are
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a part of the nervous system that carries pain signals.)
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A poetic naturalist has no trouble saying that conscious experiences ex-
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ist. They are not part of the fundamental architecture of reality, but they
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serve as essential pieces of an emergent effective theory. The best way we
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have of talking about people and their behaviors makes important reference
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to their inner mental states; therefore, by the standards of poetic natural-
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ism, those states are real, existing things.
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There is a relationship between the different ways we have of talking
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about the world, including the human- level vocabulary that includes our
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subjective experiences, and the cell- biological level that includes firing nerve
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fibers, and the particle- physics level that includes fermions and bosons. The
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relationship is that certain states in the more comprehensive theories (par-
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ticles, cells) correspond to unique states in the coarse- grained theories
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(people, experiences). The reverse relationship is typically not unique; there
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may be a large number of arrangements of atoms that correspond to “me
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being in pain.”
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A subtle but important distinction lurks between “there is a map be-
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tween the concepts of different theories” and “the concepts of the coarse-
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grained theories are to be identified with certain states in the more
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comprehensive theories,” such as “pain is to be identified with the firing of
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C-fibers.” The difference is important because granting the latter, stronger
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formulation gets us in trouble. Putnam, for example, would then want to
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ask, “Do you mean to say there can be no such thing as pain without the
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existence of C-fibers? That artificial beings, or aliens, or even very different
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animals here on Earth, are by definition incapable of feeling pain?”
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We don’t want to say that, and we don’t have to. There are certain con-
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figurations of atoms that correspond to “a human being feeling pain,” but
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there could be other configurations of atoms that correspond to “a Wookiee
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feeling pain,” or any related instantiation of the concept. (There is nothing
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in principle that prevents a computer from feeling pain.) Poetic naturalism
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is “poetic” because there are different stories we can tell about the world,
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many of them capturing some aspects of reality, and all useful in their ap-
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propriate context.
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There’s no reason for us to pretend that subjective experiences don’t ex-
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ist, or on the other hand that they “are” something happening in the brain.
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They are essential concepts within a way of talking about things happening
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in our brains, and that makes all the difference.
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Are Photons Conscious?
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f consciousness were something over and above the physical properties
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of matter, there would be a puzzle: what was it doing for all those bil-
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lions of years before life came along?
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Poetic naturalists have no problem with this question. The appearance
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of consciousness is a phase transition, like water boiling. The fact that suf-
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ficiently hot water is in the form of a gas doesn’t mean that there was always
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something gaslike about the water, even when it was in the form of liquid;
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the system simply acquired new properties as its situation changed.
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But if you believe that mental properties are an additional ingredient,
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over and above the underlying physical substrate, then the question of what
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they were doing for most of the history of the universe is a pointed one. The
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most straightforward answer is that those mental properties were always
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there, even before there were brains or even organisms. Even the individual
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atoms and particles that were bumping into one another in the early uni-
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verse, or are currently doing so at the center of the sun or in the desolate
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cold of intergalactic space, are equipped with mental properties of their
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own. They would be, in this sense, a little bit conscious.
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The suggestion that consciousness pervades the universe, and is a part of
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every piece of matter, goes by the name of panpsychism. It’s an old idea, go-
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ing back arguably as far as Thales and Plato in ancient Greece, as well as in
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certain Buddhist traditions. In its modern guise it has been contemplated
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seriously by philosophers like David Chalmers and neuroscientists such as
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Giulio Tononi and Christof Koch. Here is Chalmers, admirably biting the
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bullet and accepting the consequences of what such a view would imply:
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Even a photon has some degree of consciousness. The idea is
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not that photons are intelligent or thinking. It’s not that a pho-
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ton is wracked with angst because it’s thinking, “Aww, I’m al-
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ways buzzing around near the speed of light. I never get to slow
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down and smell the roses.” No, not like that. But the thought is
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maybe photons might have some element of raw, subjective feel-
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ing, some primitive precursor to consciousness.
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Consciousness, or at least protoconsciousness, could be analogous to
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“spin” or “electric charge”— one of the basic properties characterizing each
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bit of matter in the universe.
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It’s worth taking the implications of this idea seriously, and seeing how well
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it fits in with what we know about the physics of photons.
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Unlike brains, which are complicated and hard to explain, elementary
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particles such as photons are extraordinarily simple, and therefore relatively
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easy to study and understand. Physicists talk about different kinds of par-
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ticles having different “degrees of freedom”— essentially, the number of dif-
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ferent kinds of such particles that there are. An electron, for example, has
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two degrees of freedom. It has both electric charge and spin, but the electric
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charge can take on only one value (–1), while the spin comes in two possi-
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bilities: clockwise or counterclockwise. One times two is two, for two total
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degrees of freedom. An up quark, by contrast, has six degrees of freedom;
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like an electron, it has a fixed charge and two possible ways of spinning, but
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