Thomas Nagel’s untutored reaction of incredulity

 Mohan Matthen reviews Thomas Nagel’s new book on Darwinism, and finds that his attack falls flat. This review appears in Issue 60 of The Philosophers’ Magazine. Please support TPM by subscribing.

For some time now, Thomas Nagel has been troubled by the place of Darwinism in public intellectual life. In 2008, he argued in Philosophy and Public Affairs that Intelligent Design Theory has a place in high-school science curricula. More recently, he reviewed Alvin Plantinga’s latest anti-Darwinian book favourably in the New York Review of Books, writing, “When our faculties lead us to beliefs vastly removed from those our ancestors needed to survive ­­– as in the recent production and assessment of evidence for the existence of the Higgs boson – Plantinga’s sceptical argument remains powerful.” Now, in Mind and Cosmos,we have a more systematic treatment, which affords us a better understanding of his view.

Let us begin with the inflammatory sub-title. You might think that Nagel is offering a refutation of a scientific theory, but as far as I can tell, this is not exactly his intention (apart from a strange pronouncement I’ll discuss shortly). And it is certainly not the result of his main argument. Nagel claims that materialist neo-Darwinism (“Darwinism” for short) doesn’t offer us a certain sort of understanding: it doesn’t render the emergence of mind, consciousness, and value intelligible. For reasons I’ll outline, scientific Darwinism doesn’t claim to, and perhaps couldn’t, offer this kind of understanding.

Nagel’s reasons for thinking that Darwinism is incomplete with respect to consciousness are summarised in an argument he gives in chapter three. Suppose we knew (a) why all organisms of material constitution M are conscious and (b) how M-constituted organisms emerged by “purely physical evolution”. (a) and (b) might seem together to imply that we know how and why consciousness evolved, but Nagel thinks they do not.

For though (b) explains event types involving material constitution M, we still lack an explanation of event types involving consciousness. To understand the latter, Nagel claims, we need to know why evolution produced consciousness. Such an explanation must make it “likely” that evolution produced conscious organisms under the description “conscious”, and not merely under the description “M-constituted”. There must be such an explanation, he says, since “organisms such as ourselves do not just happen to be conscious”.

Nagel does not contest the possibility of knowing (a) and (b). (a) is a non-historical reduction of consciousness to material constitution; (b) is an evolutionary account of the emergence of the material properties underlying consciousness. Nagel’s central contention is rather that (a) and (b) together do not suffice to make the emergence of consciousness non-accidental.

Here is one reason, unconnected with materialism or Darwinism, why science would find it very difficult to offer such an explanation. Psychology is an autonomous discipline. The laws of consciousness are investigated independently of those of physics, and as a consequence, psychological concepts are independent of physical concepts. The proposition that M-constituted creatures are conscious thus conjoins independent concepts and appears to be contingent. Along similar lines: we grasp consciousness from the first-person perspective. From this perspective, consciousness is not a brain process. Thus, the proposition that mental acts are physically constituted seems contingent to us.

This conceptual gap between psychology and material science is not why Nagel dismisses Darwinism. He writes, “I suspect that the appearance of contingency in the relation between mind and brain is probably an illusion, and that it is in fact a necessary and nonconceptual connection, concealed from us by the inadequacy of our present concepts … The mind-body problem is difficult enough that we should be suspicious of attempts to solve it with the concepts and methods developed to account for very different kinds of things.” Nagel allows that we might ultimately possess a non-historical understanding of why M-constitutedcreatures are conscious. His point is rather that this still does not afford us a historical understanding of the emergence of consciousness, because the evolution of M doesn’t make consciousness likely.

This is perhaps the moment to come back to the strange pronouncement to which I earlier alluded. Nagel writes, “With regard to evolution, the process of natural selection cannot account for the actual history without an adequate supply of viable mutations, and I believe it remains an open question whether this could have been provided in geological time merely as a result of chemical accident, without the operation of some other factors determining and restricting the forms of genetic variation. It is no longer legitimate simply to imagine a sequence of gradually evolving phenotypes, as if their appearance through mutations in the DNA were unproblematic – as Richard Dawkins does for the evolution of the eye.” (Versions of this claim are repeated at many points in the book.)

Now, this isa scientific challenge to the viability of Darwinian explanation, not just a reflection on its explanatory completeness. The sufficiency of genetic variation to drive natural selection has been a central theme since R A Fisher’s great book, The Genetical Theory of Natural Selection. Nagel, a philosopher, tells us there’s not enough. Big result!But it’s completely unsupported by argument. Nagel says that he would “like to defend the untutored reaction of incredulity to neo-Darwinism … It is prima facie highly implausible that life as we know it is the result of a sequence of physical accidents together with the mechanism of natural selection”. This is just irresponsible. It is simply wrong to adjudicate the probability of mutations by an “untutored reaction of incredulity”. Probability assessments notoriously run counter to common sense. If you think you have a scientifically viable argument, give it, or leave it to scientists to deal with this kind of problem!

Returning to the philosophical content: whatever you may think of Nagel’s incompleteness of explanation argument, you still have to take a leap to conclude that this argues for a non-naturalist ontology. Grant him, for the sake of argument that evolutionary theory does not make it probable that conscious creatures will emerge. Call this the Hard Problem of Evolutionary Emergence. However that might be, neuroscientists are certainly hard at work trying to figure out how particular conscious processes are physically realised in humans and other species – call this the Easy Problem of Neurophysiological Correspondence. Solving the Easy Problem will at least enable us to figure out post hocwhat evolutionary path leads to the material substrate of consciousness.

Naturalism posits that the Easy Problem kind of explanation will always be available. This isn’t the mad hope that there is a single materialist explanation for consciousness as such, but the optimistic hope (perhaps a bit wide-eyed, but not mad) that a material account can be given for each realisation of consciousness. So even if there are grounds for pessimism about understanding the emergence of consciousness-as-such in Darwinian terms, this pessimism arises from the fragmentary nature of science and the unavailability of boundary-crossing definitions of consciousness, and not from the exclusion of any material factor.

Nagel thinks that in order to make the emergence of consciousness likely, we have to introduce a new kind of process – one that is teleologically directed toward the emergence of the right kind of genes. He wants, in other words, to supplement naturalistic science with teleological drive. But there is a serious problem with trying to expand our ontology in order to get the kind of intelligibility that Nagel wants. There is no room, given his argument, for additional causes. Recall that under (a) and (b) above, he allowed that evolution might be sufficient to cause consciousness, though not to make it intelligible. (“Explanation, unlike causation, is not just of an event, but of an event under a description.”)The way that evolution produces consciousness is by producing M-constituted creatures, according to (b). Because of (a), this suffices for it to produce conscious creatures.

If evolution by natural selection can produce conscious creatures this way, what work is left for a teleological process or other non-natural cause? It is one thing to argue that the theory of evolution can’t make the emergence of evolution intelligible. It is quite another thing to argue that evolution can’t produce conscious creatures. In fact, Nagel’s argument seems to lead in the opposite direction.

Evolutionary theory treats its outcomes as highly contingent. In Wonderful Life, Stephen Jay Gould famously wrote that “any replay of the tape would take evolution down a pathway radically different from the road actually taken”. (He shouldn’t have said “replay”: what he means is that the situation at any moment of history is compatible with radically different subsequent developments.) Nagel wants to say that this would make the emergence of consciousness, mind, and value unintelligible. The question is this: given that evolution gives causes that are sufficient to the outcome, are we justified in adding causes in order to secure non-contingency and intelligibility? Nagel thinks so.

On the face of it, this is a super-strong version of the Anthropic Principle. The Anthropic Principle states that the world is such as to make it possible for humans to exist. Proponents of the Anthropic Principle suggest that this explains why certain fundamental constants of physics take the values they do. Nagel proposes, in effect, that the universe must be such as to make the emergence of consciousness not just actual but intelligible. Since evolution is sufficient only to explain consciousness retrospectively, and not to predict it, it doesn’t make it “likely” before the fact. So he inserts causes – specifically, teleological causes – to secure predictability (hence intelligibility).

To summarise, Nagel attacks contemporary theory of evolution from two sides. He argues, first, that in order to make the emergence of consciousness intelligible, the theory needs to be supplemented by teleology. One might doubt that this is reasonable because there is no reason why the emergence of consciousness should be intelligible in his sense.

Nagel also argues that the biological/genetic variation that is required to generate the emergence of consciousness is unavailable. If correct, this would undermine evolutionary theory from within by showing that it is actually unable to provide even a causal narrative of how consciousness emerged. He does not support this charge by evidence or analysis. Even if it is on the mark, it is unclear why it is within the purview of philosophy to fix the problem or to suggest teleology as an alternative. If a scientific theory fails to do its job, scientists have to come up with a replacement.

Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature is Almost Certainly False, by Thomas Nagel (Oxford University Press), £15.99/$24.95.

Mohan Matthen is professor of philosophy at the university of Toronto. His areas of research are philosophy of biology, philosophy of mind, and ancient philosophy.

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  1. Nagel’s critique of extreme Neo-Darwinism may be a bit hit and miss. But like a naval battle you only need a few well placed hits to sink the hitherto considered unsinkable! Evolution is the best scientific theory we have to explain the diversity of the species, but when extended to address metaphysical questions it is of no value (not that this fact has stopped some Neo-Darwinists.

  2. And I regard it as simple to see why it can’t address metaphysical questions.

    In short, recursion. If consciousness and Mind are the things we use to assess the physical world, we cant use them to assess themselves if they remain a part of that physical world.

    IN short the princess of assessment itself consists in having a subject and an object. Subjects cant use rational methods to assess themselves. Pure reason can assess everything which is not pure reason.

    Which Kant said somewhere I think …:-)

    IN the end it resolves to a choice., If consciousness is a part of the physical world, then what it can produce is never more than a limited and partial view. If it lies outside the material world, then the material world can never be more than a limited and partial view.

    Oh dear. Bang goes rational materialism’s truth content. :-)

  3. “In short, recursion. If consciousness and Mind are the things we use to assess the physical world, we cant use them to assess themselves if they remain a part of that physical world.”

    That scepticism then applies to all uses that humans have put the mind to. We are creations of God? We can’t possibly know that if we are in fact creations of God. Even a claim to revelation cannot be distinguished from pure imagination. And Plantinga’s sensus divinitatis can be passed of as imaginative bunk.

    Same for idealism, solipsism and any philosophical perspective we might have.

    I find it odd that the thorough scepticism that theists and some philosophers apply to science and materialism seems to be neglected when it comes to their own pet ideas.

    Of course that’s only a problem if we are hoping for certain answers. I don’t see a problem with weighing the many possibilities and then somewhat arbitrarily choosing one:

  4. “When our faculties lead us to beliefs vastly removed from those our ancestors needed to survive ­­– as in the recent production and assessment of evidence for the existence of the Higgs boson – Plantinga’s sceptical argument remains powerful.”

    Well since our ancestors were non-thinking non-humans that sort of buggers up any theistic claims about God, since our ancestors had no survival need for thoughts of God.

    Again theists don’t apply the same level of scepticism to their own ideas. Totally bogus.

    Odd also that there is a reference here to survival in what appears like evolutionary sense. Prepared to accept just enough science to fit their own case, but conveniently sceptical when it suits them.

  5. Teleology doesn’t add causes of the events it renders intelligible. It seeks instead to subsume the already existing causes under a process that would non-accidentally include them. This doesn’t help Nagel’s “internal” claim about the commonsensical “incredulity” to Darwinism, which is rightly dismissed here. But it separates that claim from the demand of “intelligibility,” which does not require that a “complete,” teleological account do any causal work. Don’t confuse his bad science with his unusual philosophy.

  6. Teleological accounts don’t add causes, they only subsume existing ones under a process in which they’re not accidental (as they otherwise would be). Don’t confuse Nagel’s bad science with his strange philosophy.

  7. “Life is an urge of the universe to understand itself”.

    Read it online somewhere recently, and just seems apt in relation to Nagel’s latter work (to an untutored philosophy tyro like me).

  8. Brett,

    It’s a nice notion, but comes complete with the hopeless teleological implications appeal to mystics.

    So, to begin with, it depends on what is meant by ‘urge’. If like a biological urge, physiological drive, the non-teleological playing out of physics as emergent complexity, then there may well be a tendency for universes like ours to produce complex systems like us.

    But not “an urge to understand itself”. As a metaphor it sort of works. We use teleological language metaphorically quite naturally: “My car refuses to start. It’s so suborn sometimes that I swear it knows when I have an important appointment.” But of course in cases like that we know it’s metaphorical. The universe has no more urge to understand itself than the car has to understand the owner’s intentions or any urge to thwart them.

    The problem is that the mystics like to take it more literally. They really do think the universe possesses some sort of consciousness. But there is zero evidence of that. Without evidence, strong evidence, literal interpretations of notions like this are no better that imaginative fantasies, and as such rank in credibility along with fairies, the FSM, or Russell’s Teapot.

    It’s poetic metaphorical language like this that mystics read from scientists and assume the scientist shares some deep mystical understanding of the consciousness of the universe. Quiz the scientist directly on that point and they’ll general clarify that they do not share in such woo.

  9. It may be that Nagel’s arguments, as presented in his book, are deficient, and for some of the reasons here described.

    But it does strike me that this criticism (and virtually all of the others I’ve read) doesn’t squarely meet the problems Nagel is alluding to.

    The real problem facing a purely materialist conception of the world is some version of what is here called The Hard Problem of Evolutionary Emergence. The purely naturalistic approach, as it is ordinarily conceived, has NO answer to that problem. Consciousness exists, it has arisen, but there is nothing approaching reasonable comprehension of consciousness or how it came about. Moreover, insofar as the problem is truly Hard, it’s reasonable to speculate that there will never be an answer on purely naturalistic grounds. If, in sticking to naturalism, we don’t comprehend it, and, a fortiori, our science doesn’t understand it, then we can scarcely pretend that we are in an adequate explanatory position.

    Now maybe every alternative approach and attempted explanation, including teleology in any form, is only less satisfying. But that is a more challenging argument.

  10. I meant,

    The real problem facing a purely *naturalistic* conception…

  11. candid_observer

    Looking at early conceptualisations of flying humans it was probably reasonable to speculate that we’d never get off the ground.

    Advanced science appears like magic, and all that? Arguments from incredulity? Historically many insurmountable problems have turned out to be surmountable.

    “The purely naturalistic approach, as it is ordinarily conceived, has NO answer to that problem.”

    It’s quite conceivable that there is no real problem, but simply a current inability to see what the answer is. Seeing problems vanish as understanding increases is another common theme of the history of ideas and science. The problem may be really hard for us now. But that’s a parochial view from our point in time.

    On the issue of technology, I’m not sure it matters. Consciousness may not be restricted to human real-time.

    Do you presume any machine consciousness needs to emulate human consciousness, when perhaps it need not. If we want to verify that machinery is conscious by comparison with wet consciousness there are many simpler animal models to go at.

    The ‘hard problem’ seems to be limited in its parochial vision over time, and in its scope of what counts as success. The hard problem may be a difficult one, but not an impossible one.

    “If, in sticking to naturalism, we don’t comprehend it, and, a fortiori, our science doesn’t understand it, then we can scarcely pretend that we are in an adequate explanatory position.”

    That’s not the way it needs to work. It’s quite possible to have a good explanatory theoretical model that is usefully predictive without conceptually understanding what’s going on. Quantum physics?

    We might be able to build artificial brains that work and appear conscious sufficiently for us to confer personhood on them, to the extent that some do now with apes and dolphins. We don’t understand their consciousness any more than ours, but we recognise it and acknowledge.

    Come to that, the theory of mind is all about thinking we recognise consciousness in others in the first place, based on a sample set of one – our own personal mind. It is particularly ironic that the very people that assert we will never understand consciousness seem to understand it just enough to make that assertion. Could you explain that one?

    The very fact that naysayers have difficulty defining consciousness themselves should be a clue that they don’t understand it sufficiently to be asserting it will never be understood.

    Maybe we’re still a long way off, but closer than you think.

  12. Really surprised to this: “More recently, he reviewed Alvin Plantinga’s latest anti-Darwinian book favourably in the New York Review of Books,” It’s really disappointing to see that well known philosophers have such a hard time understanding Plantinga’s simple argument. His book is not “anti-Darwin”. Quite the opposite. Evolutionary theory, as most understand Plantinga’s argument, is the premise. And having heard Plantinga speak on this topic several times, he is a committed evolutionary theist.

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