The remark is not only unkind but unjust. At the beginning of his review, Dupré gives the impression that Nagel is attacking neo-Darwinian evolutionary biology per se. Dupré writes:
Darwinism, neo- or otherwise, is an account of the relations between living things past and present and of their ultimate origins, full of fascinating problems in detail, but beyond any serious doubt in general outline. This lack of doubt derives not, as Nagel sometimes insinuates, from a prior commitment to a metaphysical view -- there are theistic Darwinists as well as atheistic, naturalists and supernaturalists -- but from overwhelming evidence from a variety of sources: biogeography, the fossil record, comparative physiology and genomics, and so on. Nagel offers no arguments against any of this, and indeed states explicitly that he is not competent to do so. His complaint is that there are some explanatory tasks that he thinks evolution should perform that he thinks it can't.
Indeed, it is this conjunction of neo-Darwinism with materialism that is the target of Nagel’s attack in the book -- not neo-Darwinian evolutionary theory per se and certainly not evolution more generally. Nagel does not want to abandon evolutionary explanations, and he does not deny that many such explanations have empirical evidence in their favor. Rather, he wants to situate evolutionary theory within a different, non-materialist metaphysics.
As Dupré acknowledges, in Nagel’s view the main obstacles to a completely materialistic-cum-Darwinian account of the world are consciousness, rationality, and moral value. And Dupré seems to allow that whether these phenomena can be accounted for in materialist neo-Darwinian terms is indeed at least in part a philosophical (as opposed to purely biological) question, and that even philosophers committed to naturalism are divided on the question. Hence while Nagel’s proposed alternative to materialism (a kind of neo-Aristotelian but non-theistic teleology) is certainly a minority view, that it is an attempt to deal with a real problem is something even many of Dupré’s fellow naturalists will concede. So why all the scorn (as opposed to mere disagreement) on Dupré’s part?
In part the reason is that Dupré thinks Nagel is attacking a straw man insofar as Nagel characterizes materialism as inherently reductionistic. For in fact (and as other reviewers have rightly pointed out, as we’ve seen in earlier posts) reductionism has largely been abandoned by contemporary philosophers of science. (Dupré, an important and interesting anti-reductionist philosopher of science, deserves part of the credit for this.) Dupré writes:
Nagel expresses a view that was popular among philosophers of science half a century ago, and has been in decline ever since. It is a view that is perhaps still common among philosophers of mind (David Chalmers much discussed book The Conscious Mind (1996), for example, bases its argument for dualism on a similar view of materialism), but reductionism has been almost entirely rejected by philosophers actually engaged with the physical and biological sciences: it simply has no interesting relation to the diversity of things that scientists actually do.
But while Dupré is right about reductionism in philosophy of science, there are two problems with his remarks considered as a criticism of Nagel. First of all, Dupré himself allows that a reductionist construal of materialism is at least still operative in much work within the philosophy of mind. Yet as Dupré realizes, Nagel’s criticisms of materialism largely concern precisely this philosophical sub-discipline, insofar as he puts so much emphasis on the impossibility of a reductionist account of consciousness and rationality. So, if reductionism is still a live issue in the philosophy of mind, Nagel can at least to that extent hardly be accused of attacking a straw man.
But secondly and more importantly, even if reductionism were no longer an issue even in the philosophy of mind, Dupré’s complaint would not really be a serious objection to Nagel. For it is no good merely to point out that reductionism is no longer in fashion among naturalists. The question is whether they can reject reductionism consistent with maintaining a position that can in any interesting sense be called “naturalistic.” In particular, non-reductionistic versions of materialism have a tendency to collapse into either property dualism -- the sort of view defended by Chalmers -- or a quasi-Aristotelian commitment to formal and final causes -- which (as I noted in my own review of Nagel) is essentially what Nagel is defending. So, if one rejects both Chalmers’ and Nagel’s views (as, of course, Dupré does) it is no good to note that most naturalists are no longer reductionists, and leave it at that. One needs to show that this anti-reductionism doesn’t effectively put these naturalists precisely into either Chalmers’ camp or Nagel’s; and Dupré does nothing to show this.
As we saw in the previous post in this series, another critic of Nagel, Alva Noë, recognizes that there is a real problem here. Noë writes:
Some reviewers… seem glad to dismiss Nagel's call to arms. This may be because they find it implausible that either philosophy or the practice of science is committed today to… [the] idea that, theoretically at least, reality is physical and that physics therefore is the fundamental science of reality. Very few thinkers today seek to reduce neuroscience to biology, biology to chemistry, and chemistry in its turn to physics. In practice, these are recognized to be autonomous domains.
This is right, but it is a superficial and unsatisfying observation. For there is no stable or deeply understood account of how these autonomous domains fit together. The fact that we are getting along with business as if there were such an account is, well, a political or sociological fact about us that should do little to reassure. And anyway, as Nagel urges, the fact remains that where mind is concerned, not to mention society and economics, we lack sciences that are well-established, well-grounded and successful, loud pronouncements to the contrary notwithstanding. We haven't explained life and mind.
End quote. Now to this sort of criticism, it seems that Dupré would reply that whatever difficulties face materialistic accounts of consciousness, rationality, etc., they are outweighed by the considerations in favor of a broadly materialistic-cum-Darwinian view of the world. Dupré writes:
What seems to me beyond any serious question is that the results and insights gained by the vast quantities of philosophical and quasi-philosophical work on consciousness in the last few decades is hardly comparable with the successes that stand to the credit of evolution.
But here I will only repeat that we have surely not been offered anything harder to deny than the general truth of evolution.
But there are two problems with such a retort. First of all, the success of existing Darwinian explanations simply does nothing by itself to show that they are likely to be sufficient explanations of all biological phenomena, including consciousness and rationality. Here Dupré seems to be making a mistake which so many naturalists (including some of Nagel’s other critics) make -- namely, fallaciously drawing a metaphysical conclusion from a methodological premise. The success of metal detectors does not by itself give us any reason to think that everything in the natural world must be the sort of thing metal detectors detect (e.g. coins, nails, etc.). And the success of materialistic-cum-Darwinian methods of explanation does not by itself give us any reason to think that everything in the biological realm must be the sort of thing of which a materialistic-cum-Darwinian explanation can be given.
Of course, we already have independent reason for thinking that non-metallic objects exist. But then, we also have independent reason for thinking that there are biological phenomena -- such as consciousness and rationality -- which cannot be given a materialistic-cum-Darwinian explanation. Indeed, as we have seen in the previous posts in this series, Nagel has in previous works (his book The Last Word, his article “What Is It Like to Be a Bat?” and elsewhere) developed important lines of argument (only summarized in the new book) which imply that it is impossible in principle to account for consciousness and rationality in materialistic-cum-Darwinian terms.
And that brings us to the second problem with Dupré’s retort. If someone gives you an argument which purports to demonstrate that there cannot possibly be an explanation of X in terms of Y, it is no response at all merely to assert that the general success of Y-explanations indicates that X must after all be explainable in terms of Y. To borrow an example from my post on Noë, it would be absurd for a critic of Gödel to suggest that the general success of our methods of proof shows that Gödel's incompleteness theorems must be mistaken. No one would take such a critic seriously for a moment unless he somehow showed, directly and without a hand-waving appeal to the general success of our formal methods, that the arguments for Gödel's theorems contained some heretofore unknown flaws. For unless he does so, such a critic would simply be missing the point or begging the question. Similarly, unless Dupré gives us some direct refutation of Nagel’s arguments against the possibility in principle of a materialistic-cum-Darwinian explanation of consciousness and rationality, his appeal to the general success of evolutionary explanations also merely misses the point or begs the question. And yet Dupré gives us no such refutation. He says that “this is not the place to pursue” Nagel’s arguments about consciousness, and that the issues Nagel raises about rationality are “deep waters, no doubt” which cannot be plumbed in the scope of a review. Hence he rests his case on a mere appeal to the general success of evolution -- as if this did anything mere than merely reassert the very claim Nagel has argued against, rather than answering Nagel’s arguments!
Similarly question-begging are Dupré’s remarks about probabilities and about the content of a non-reductionist form of materialism. On the former subject Dupré writes:
Nagel constantly asserts that to explain the existence of consciousness, etc., evolution must not just show that they are possible, but also that they are likely, or to be expected. This is, I suppose, a further expression of his rationalism, the expectation of a certain kind of intelligibility. But still it seems to me poorly motivated. At the time of my birth it was very unlikely that I would several decades later be reviewing a book by a famous philosopher; but it is not mysterious that this eventually came about. The improbability has been declining rapidly for the last few decades. Just so with evolution. The evolution of reason may well be very unlikely indeed on a young, hot planet. It's a great deal more likely by the time there are highly social, if not yet rational, multicellular organisms with very complex nervous systems.
End quote. The problem with this, as we saw in earlier posts in this series (since some of Nagel’s other critics make similar claims), is that the reason consciousness and rationality are in Nagel’s view unlikely on a purely materialistic-cum-Darwinian picture of nature is not the same kind of reason that it is unlikely that a newborn Dupré would grow up to review a book by a famous philosopher. The latter scenario is improbable but not impossible. But if Nagel’s arguments concerning consciousness and rationality are correct, then it is in principle impossible to get consciousness and rationality out of nothing more than materialistic-cum-Darwinian processes. You might as well say (once again to borrow an example from the earlier posts) that you can get a true circle out of a polygon if you add enough sides.
On the question of what an anti-reductionistic materialism would look like, Dupré writes:
A more sensible materialism goes no further than the rejection of spooky stuff: whatever kinds of stuff there may turn out to be and whatever they turn out to do, they are, as long as this turning out is empirically grounded, ipso facto not spooky. Such a materialism is quite untouched by Nagel's arguments.
But surely the problem with this is obvious. This characterization of non-reductionistic materialism is completely unhelpful unless we have some non-question-begging explanation of what counts as “spooky.” And that is something Dupré does not give us. In particular (and to repeat a point made above) Dupré does not tell us how a non-reductionistic materialism differs from either property dualism or neo-Aristotelianism. Perhaps he would say that materialism differs from these other views in not being committed to paradigmatically “spooky” entities like ectoplasm, vital spirits, gods-of-the-gaps, and the like. But if so, then he would be attacking a caricature, since (as I noted earlier in this series of posts) neither the Cartesian nor the Aristotelian is actually committed to these hoary straw men.
Perhaps Dupré would say instead that while the property dualist’s immaterial properties, the Aristotelian’s formal and final causes, and the like are not “spooky” in the way these other entities are, they are nevertheless not empirically grounded. But that is false. The property dualist would say that the existence of qualia is in fact as empirically grounded as anything could be, since we know them from introspection. It is true that the arguments for their immateriality appeal to further theoretical considerations, but (as philosophers of science have been emphasizing now for decades) that is true of all empirically-based arguments.
Aristotelian notions like the theory of act and potency, hylemorphism, and the like are also empirically grounded. To be sure, they are not empirically grounded in the same way that theories in physics, chemistry, and the like are empirically grounded, insofar as they are not subject to falsification of the sort the latter theories are. The reason is that they are claims about issues in the philosophy of nature rather than in empirical science -- that is to say, claims about what any possible empirical world has to be like if we are to have scientific knowledge of it, whereas physics, chemistry, etc. concern the specific sort of empirical world that actually exists. (I have explained the relationship between the philosophy of nature and empirical science in an earlier post.) Still, insofar as they start from the most general features of empirical reality as we know it from experience (such as the fact of change), they are empirically grounded.
(It is this generality that makes the difference between the disciplines. We know from experience that change exists. But the existence of change is nevertheless not empirically falsifiable in the same way that theories in physics and chemistry are, because any experience or set of experiences that could be put forward to falsify it would themselves be instances of change. Thus, if you are going to try to defend a radically non-Aristotelian philosophy of nature -- for example, one that denies change altogether -- you are going to have to do so on the basis of considerations that go beyond anything physics, chemistry, etc. or experience in general can tell you. That is to say, if you are going to falsify Aristotelianism, you are not going to be able to do it on observational or experimental grounds, but only on competing philosophical grounds.)
So, merely to say that a “sensible materialism” would reject “spooky” entities, in the sense of entities belief in which has no empirical grounding, is not yet to explain how a sensible materialism differs from either property dualism or Aristotelianism. If Dupré at this point were simply to stipulate that entities of the sort the property dualist or Aristotelian would allow don’t count, his position would be entirely ad hoc. And if he has some principled reason for excluding them, he doesn’t tell us what it is (at least not in his review).
So, bluster notwithstanding, Dupré has not actually presented any criticisms of Nagel that are not either aimed at caricatures, or question-begging, or ungrounded or beside the point. And it is ironic in the first place that he is as critical of Nagel as he is, since Dupré’s important work in defense of a non-reductionistic philosophy of science only bolsters the neo-Aristotelian position -- and thus, indirectly, Nagel’s position.