Here I wish to offer a critique of a review on record at Notre Dame's Philosophical Reviews by John Dupré. I found this review to be almost entirely derisive of Nagel's work. Dupré writes early on, "I found this book frustrating and unconvincing," and goes on to say that Nagel fails to argue against the Darwinian account, which, from Dupré's standpoint, is supported by "overwhelming evidence." As one can see from my previous review of Mind and Cosmos, I found Nagel's work to do a commendable job of rebutting neo-Darwinism. Thus, I must disagree with Dupré.
Dupré attempts to take Nagel to task for embracing a kind of rationalism. Dupré contrasts rationalism with atheism, but traditionally rationalism is contrasted with empiricism: Rationalism holds that some understanding is derived independent of experience whereas empiricism holds that all understanding is derived from experience. Thus, I do not know exactly how Dupré intends the term rationalism to be understood, but in the context he quotes the following from Mind and Cosmos: "everything about the world can . . . be understood (p. 17)". This quote from Nagel, though, is actually a definition of the principle of sufficient reason. Here's the full quote from Mind and Cosmos:
This assumption is a form of the principle of sufficient reason--that everything about the world can at some level be understood, and that if many things, even the most universal, initially seem arbitrary, that is because there are further things we do not know, which explain why they are not arbitrary after all (17).Dupré does not address the principle of sufficient reason directly, so I cannot say whether he rejects it or not. As far as Nagel's project is concerned, there is nothing irresponsible about announcing his embrace of the principle of sufficient reason and assessing the explanatory powers of the natural sciences in light of the principle. Certainly, one can take issue with the principle of sufficient reason itself (such a strategy was recently employed by Alex Rosenberg in debate with William Lane Craig), but Nagel's use of the principle in his book is not automatically defective. Indeed, the natural sciences themselves seem to be largely motivated by the essence of the principle--what is a scientific "success" other than the comprehensive explanation of a natural phenomenon?
Dupré goes on to make a very odd claim: "It would not be an exaggeration to say that for Nagel, if science can't come up with a theory of everything it has, in some deep sense, failed. Nagel is thus, in effect, committed a priori to reductionism; the failure of reductionism is therefore the failure of science." What strikes me as odd about these two sentences is the questionable use of the term "science." Nagel is not targeting "science" in his work; rather, he's targeting what he alternately calls "materialism" and "psychophysical reductionism." These are metaphysical positions. Science, by contrast, is a brand of empirical epistemology--i.e., it is a method. Insofar as something is said to "fail" in Nagel's book, it is the metaphysical propositions of materialism or psychophysical reductionism. Nagel does not deny that the natural sciences have a great deal of authority with respect to the contents of the natural world; instead, he calls into question whether this authority exhausts all that can be said about the natural world:
But in spite of the great accomplishments of the natural sciences in their present form, it is important both for science itself and for philosophy to ask how much of what there is the physical sciences can render intelligible--how much of the world's intelligibility consists in its subsumability under universal, mathematically formulable laws governing the spatiotemporal order. If there are limits to the reach of science in this form, are there other forms of understanding that can render intelligible what physical science does not explain? (18).In an effort to argue that the answer to the previous question is yes, Nagel offers three related areas that the methods of science, and therefore the metaphysics of materialism, cannot explain: consciousness, cognition, and value. With respect to consciousness, Nagel offers familiar philosophical arguments suggesting that irreducibly subjective first-person properties like qualia are irreconcilable with purely materialist metaphysics. Dupré offers the following assessment of Nagel's argument from consciousness: "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."
First of all, it is entirely unclear why this comparison is relevant to the potency of Nagel's argument. Would it be any criticism of evolution to point out that its insights pale in comparison to the successes of particle physics? How exactly does one even compare the insights of philosophy of consciousness with evolutionary successes? Remember, Nagel's argument from consciousness is not directly opposed to evolution; it is instead directly opposed to materialism. Evolution is only challenged by the implications of a falsified materialist metaphysics.
Second, what exactly are these evolutionary successes? Dupré criticizes Nagel for failing to offer arguments against neo-Darwinism (Nagel does, however, provide citations), yet Dupré fails to provide support for these evolutionary successes. In the realm of "junk" DNA, current research appears to disconfirm the predictions of evolution. For example, consider this article's opening line: "Research findings from the University of North Carolina School of Medicine are shining a light on an important regulatory role performed by the so-called dark matter, or 'junk DNA,' within each of our genes." Surely, such findings do not count as evolutionary "successes." Furthermore, even though it is ridiculed to do so, I strongly recommend consulting the recent works of the research fellows at the Discovery Institute for cogent empirical challenges to the "successful" status of Darwinian evolution. Ultimately, I think Durpé is relying on the buoyant powers of the consensus view to carry his claim. Since Nagel is challenging this consensus, it is ineffective to merely reassert the consensus view--this view must be defended in light of contemporary objections.
Dupré's use of evolution as a measure of success continues with respect to his criticism of Nagel's argument from cognition:
Nagel thinks that reason gives us insights into reality that evolution cannot account for....My own views are, first, that the mediating mental effect in perception is a highly problematic entity, and second that surely logic is at least mediated by language. But here I will only repeat that we have surely not been offered anything harder to deny than the general truth of evolution."Leaving aside whether the "general truth of evolution" is as strong as Dupré leads us to believe, let's consider the relationship between reason itself and "the general truth of evolution." Suppose we concede "the general truth of evolution"; what does this imply? It implies that our conscious minds have reached far enough outside of themselves to apprehend a genuine piece of objective reality--something the sense perceptions themselves could not possibly reach alone. It is not a "snapshot" of our immediate environment, nor a behavioral impulse. It is a universal proposition about reality itself: "In ordinary perception, we are like mechanisms governed by a (roughly) truth-preserving algorithm. But when we reason, we are like a mechanism that can see that the algorithm it follows is truth-preserving" (Mind and Cosmos, 83). Objective reasoning is not simply the summation of a number of sense perceptions accumulated over years of evolution--it is instead an ability over and above evolution that makes claims like "the general truth of evolution" comprehensible and, ultimately, evaluable. Therefore, not only is it harder to deny the insights of reason than the general truth of evolution, it is impossible to deny the insights of reason while still holding there is such a thing as "the general truth of evolution."
Finally, Dupré slips into his review a comment about the effect Nagel's book is likely to have on those friendly to intelligent design: "The title of the book...all too readily interpreted as announcing the falsity of Darwinism, will certainly lend comfort (and sell a lot of copies) to the religious enemies of Darwinism." My only response is this: So what?