Back in the Dark Ages, a person with heretical theological beliefs would occasionally be burned at the stake. Nowadays, when a more scientific worldview has triumphed and everyone knows that God doesn’t exist, the tables have turned, and any slight deviation from scientific/naturalist/atheist/Darwinian doctrine will have you literally tied to a pole and set on fire. Fair is fair.
Or, at least, people will write book reviews and blog posts that disagree with you. But I think we all agree that’s just as bad, right?
The ominous image shown here was the cover of an issue of The Weekly Standard back in March, illustrating a piece by Andrew Ferguson. The poor heretic being burned is Thomas Nagel, philosopher at NYU and the author of Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False. The crowd of sinister hooded pyrophiliacs includes–well, me, actually, as well as the other participants in our Moving Naturalism Forward workshop. As Ferguson points out, there is irrefutable video evidence that we accused people like poor Tom Nagel of being “neither cute nor clever.” Many might perceive an important distinction between saying someone is not clever and roasting them alive, but potayto, potahto, I guess.
It’s true that Nagel’s book has occasioned quite a bit of discussion, much of it negative. For a sampling from various viewpoints, see Elliott Sober, Brian Leiter and Michael Weisberg, Michael Chorost, H. Allen Orr, Malcolm Nicholson, and Jerry Coyne. The reason for all the fuss is, of course, that the materialist Neo-Darwinist conception of nature is almost certainly true, so it’s worth pushing back against a respected philosopher who says otherwise.
(By the end of this overly long post I will suggest that Nagel, despite being generally way off track, nevertheless has a bit of a point that many people seem to be passing over. Much like the Insane Clown Posse in a different context.)
This week Nagel took to the NYT to publish a brief summary of his major arguments, for those who haven’t read the book. There are basically two points. The first is that the phenomenon of consciousness cannot be explained by the workings of inanimate matter alone; you need more than the laws of physics.
The physical sciences can describe organisms like ourselves as parts of the objective spatio-temporal order – our structure and behavior in space and time – but they cannot describe the subjective experiences of such organisms or how the world appears to their different particular points of view. There can be a purely physical description of the neurophysiological processes that give rise to an experience, and also of the physical behavior that is typically associated with it, but such a description, however complete, will leave out the subjective essence of the experience – how it is from the point of view of its subject — without which it would not be a conscious experience at all.
This is an old idea, and Nagel’s sympathy for it can be traced back to his influential paper “What Is It Like To Be a Bat?”. The claim is that there is something inherently subjective about the experience of consciousness, something that cannot be shared with other conscious beings nor described by physics. (Even if you know every physical fact about bats, you still don’t know what it’s like to be a bat.) This position has been developed in subtle ways by philosophers like David Chalmers. Nagel actually doesn’t spend too much time providing support for this stance, as he wants to take it as understood and move on.
The second and more important point is that, because of the first point, a purely physical view of the world is incomplete, and we have to add something to it, and that addition is going to end up being pretty dramatic. Nagel believes that an adequate explanatory framework must not merely be compatible with life and consciousness, but actually entail that these dramatic and central features of reality are “to be expected” — that there is a “propensity” in nature for them to arise. Since he doesn’t see such a propensity anywhere in physics, he thinks the conventional view by itself fails as an explanation.
[S]ince the long process of biological evolution is responsible for the existence of conscious organisms, and since a purely physical process cannot explain their existence, it follows that biological evolution must be more than just a physical process, and the theory of evolution, if it is to explain the existence of conscious life, must become more than just a physical theory.
In particular, he claims that the standard scientific picture must be augmented by a non-physical notion of teleology — directedness toward a purpose. And not just an emergent notion of purpose that might be compatible with physicalism. Nagel is thinking of something fundamental: “teleology requires that successor states . . . have a significantly higher probability than is entailed by the laws of physics alone.”
So Nagel rejects “scientific naturalism” or “reductionism” or “materialism” or “physicalism,” but also rejects theism. He wants to find a middle ground, which he labels “antireductionism”; this need not necessarily entail a rejection of naturalism, and indeed he at one point uses the phrase “teleological naturalism” in a sympathetic way. He doesn’t seem to think we need to look beyond the natural world, but we do need to look beyond the laws of physics.
In the responses to his book, much has been made of the fact that a lot of Nagel’s reasoning is not very good. He repeatedly invokes “common sense,” and puts forward the Argument From Personal Incredulity in an especially unapologetic manner:
[F]or a long time I have found the materialist account of how we and our fellow organisms came to exist hard to believe, including the standard version of how the evolutionary process works… This is just the opinion of a layman who reads widely in the literature that explains contemporary science to the nonspecialist.
Given that he is admittedly not an expert in the scientific fields he is willing to label as “almost certainly false,” there must be a deep-seated reason underlying Nagel’s conviction. That reason seems to be the enormous importance he places on the “intelligibility” of nature. This is something like the Principle of Sufficient Reason (which he mentions). Nagel believes that the specific laws of nature, or even the fact that there are such laws at all, and that we can understand them, are all things that require an explanation. They cannot simply be (as others among us are happy to accept). And the only way he can see that happening is if “mind” and its appearance in the universe are taken as fundamental features of reality, not simply byproducts of physical evolution.
Try as I might, I cannot quite appreciate the appeal of this program. I could imagine that, after much effort were expended experimentally and theoretically, we might ultimately come to believe that the best explanatory framework for the appearance of consciousness in the universe involves positing mind as a separate category. What I don’t understand is the a priori-sounding argument that this would necessarily be a better explanation. If Nagel can demand an explanation for why the world is intelligible, why can’t I demand an explanation for why mind is a separate category, or why the universe has teleological tendencies? I don’t see the distinction; in either case, one must take certain facts about reality as simply given. My preference would be to minimize the weight given to our intuitive ideas about what form a proper explanation should take, and keep looking for the simplest and most powerful model that fits the data.
(This issue is related to a point that gets raised when I mention that we understand the laws of physics underlying everyday life. Inevitably someone says that we don’t really understand gravity, man. They’re not claiming that general relativity fails to provide a model that successfully fits all the known data; they’re claiming that the existence of such a model doesn’t count as “understanding.” People who deny that physics can ever account for consciousness have a similar idea; even if we had a complete theory that accounted for every possible observable action of purportedly conscious creatures, they would not be satisfied that this qualified as “understanding” or “explanation.” For me, that’s just a misunderstanding of what kinds of explanations we can legitimately hope for.)
However! Let me stake out a brave contrarian position among my anti-Nagelian friends by pointing out something important that I think he gets right. Namely, point number two above (scientific materialism is incomplete and needs to be augmented by something apart from the physical) actually does follow, under plausible assumptions, from point number one (consciousness cannot be explained in purely physical terms). Nagel is correct to have appreciated that once you say “consciousness isn’t merely physical” (or indeed once you’ve accepted the kind of strong antireductionism that is relatively popular in contemporary philosophy), the ramifications for fundamental science are profound indeed.
Except, of course, I want to use this to reach the opposite conclusion: the idea that we need something like a non-material teleological principle, a “propensity” in nature for things to develop a certain way, is so dramatically at odds with what we’ve learned about the world in the time since Galileo that it gives us good reason to deny that consciousness can’t be explained in physical terms.
Imagine what it would entail to truly believe that consciousness is not accounted for by physics. It would entail, among other things, that the behavior of ordinary matter would occasionally deviate from that expected on the basis of physics alone, even in circumstances where consciousness was not involved in any obvious way. Several billion years ago there weren’t conscious creatures here on Earth. It was just atoms and particles, bumping into each other in accordance with the rules of physics and chemistry. Except, if mind is not physical, at some point they swerved away from those laws, since remaining in accordance with them would never have created consciousness. In effect, the particles understood that sticking to their physically prescribed behaviors would never accomplish the universe’s grand plan of producing conscious life. Teleology is as good a word for that as any.
So, at what point does this deviation from purely physical behavior kick in, exactly? It’s the immortal soul vs. the Dirac equation problem–if you want to claim that what happens in our brain isn’t simply following the laws of physics, you have the duty to explain in exactly what way the electrons in our atoms fail to obey their equations of motion. Is energy conserved in your universe? Is momentum? Is quantum evolution unitary, information-preserving, reversible? Can the teleological effects on quantum field observables be encapsulated in an effective Hamiltonian?
This is not a proof that consciousness must be physical (as some folks will insist on misconstruing it), just an observation of the absolutely enormous magnitude of what the alternative implies. Physics makes unambiguous (although sometimes probabilistic) statements about what will happen in the future based on what conditions are now. You can’t simply say that physics is “incomplete,” because on their own terms physical theories are not incomplete (within their domain of applicability). Either matter obeys the laws of physics, or physics is wrong. And if you want us to take seriously the possibility that it’s wrong, you better have at least some tentative ideas about what would be a better theory.
Of course, Nagel has no such theory, which he cheerfully admits. That’s for the scientists to come up with! He’s just a philosopher, he says.
Which is why, at the end, his position isn’t very interesting. (Because he doesn’t have anything like a compelling alternative theory, not because he’s a philosopher.) He advocates overthrowing things that are precisely defined, extremely robust, and impressively well-tested (the known laws of physics, natural selection) on the basis of ideas that are rather vague and much less well-supported (a conviction that consciousness can’t be explained physically, a demand for intelligibility, moral realism). If someone puts forward even a rough sketch of how a new teleological view of reality might actually work, including how it affects the known laws of physics, that might be very interesting. I don’t think the prospects are very bright.