I've just finished reading Thomas Nagel's newish book, "Mind and Cosmos" (Oxford, 2012). It's deeply flawed, but in spite of its flaws some of the points it makes deserve more attention, especially in the broader culture, than they're likely to receive in the context of a book that's gotten plenty of people exercised about its flaws. I'm currently undecided about whether to recommend reading his book for these points, as they are probably made, without the distracting context and possibly better formulated, equally well elsewhere, notably in Nagel's "The Last Word" (Oxford, 1997). The positive points are the emphasis on the reality of mental phenomena and (more controversially) their ireducibility to physical or even biological terms, the unacceptability of viewing the activities of reason in similarly reductive terms, and a sense that mind and reason are central to the nature of reality. Its greatest flaws are an excessively reductionist view of the nature of science, and, to some degree in consequence of this, an excessive skepticism about the potential for evolutionary explanations of the origins of life, consciousness, and reason.
One of the main flaws of Nagel's book is that he seems --- very surprisingly --- to view explananations in terms of, say, evolutionary biology, as "reductively materialist". He seems not to appreciate the degree to which the "higher" sciences involve "emergent" phenomena, not reducible---or not, in any case, reduced---to the terms of sciences "below" them in the putative reductionist hierarchy. Of course there is no guarantee that explanations in terms of these disciplines' concepts will not be replaced by explanations in terms of the concepts of physics, but it has not happened, and may well never happen. The rough picture is that the higher disciplines involve patterns or structures formed, if you like, out of the material of the lower ones, but the concepts in terms of which we deal with these patterns or structures are not those of physics, they are higher-order ones. And these structures and their properties---described in the language of the higher sciences, not of physics---are just as real as the entities and properties of physics. My view --- and while it is non-reductionist, I do not think it is hugely at variance with that of many, perhaps most, scientists who have considered the matter carefully --- is that at a certain very high level, some of these patterns have genuine mental aspects. I don't feel certain that we will explain, in some sense, all mental phenomena in terms of these patterns, but neither does it seem unreasonable that we might. ("Explanation" in this sense needn't imply the ability to predict perfectly (or even very well), nor, as is well known, need the ability to predict perfectly be viewed as providing us with a full and adequate explanation---simulation, for example, is not necessarily understanding.) Among scientists and philosophers who like Nagel hold a broadly "rationalist" worldview David Deutsch, in his books The Fabric of Reality and especially The Beginning of Infinity, is much more in touch with the non-reductionist nature of much of science.
Note that none of this means there isn't in some sense a "physical basis" for mind and reason. It is consistent with the idea that there can be "no mental difference without a physical difference", for example (a view that I think even Nagel, however, agrees with).
This excessively reductionist view of modern science can also be found among scientists and popular observers of science, though it is far from universal. It is probably in part, though only in part, responsible for two other serious flaws in Nagel's book. The first of these is his skepticism about the likelihood that we will arrive at an explanation of the origin of life in terms of physics, chemistry, and perhaps other sciences that emerge from them---planetary science, geology, or perhaps some area on the borderline between complex chemistry and biology that will require new concepts, but not in a way radically different from the way these disciplines themselves involve new concepts not found in basic physics. The second is his skepticism that the origins of consciousness and reason can be explained primarily in terms of biological evolution. I suspect he is wrong about this. The kind of evolutionary explanation I expect is of course likely to use the terms "consciousness" and "reason" in ways that are not entirely reductive. I don't think that will prevent us from understanding them as likely to evolve through natural selection. I expect we will see that to possess the faculty of reason, understood (with Nagel) as having the---fallible, to be sure!---power to help get us in touch with a reality that transcends, while including, our subjective point of view, confers selective advantage. Nagel is aware of the possibility of this type of explanation but --- surprisingly, in my view --- views it as implausible that it should be adaptive to possess reason in this strong sense, rather than just some locally useful heuristics.
The shortcomings in his views on evolution and the potential for an evolutionary explanation of life, consciousness, and reason deserve more discussion, but I'll leave that for a possible later post.
The part of Nagel's worldview that I like, and that may go underappreciated by those who focus on his shortcomings, is, as I mentioned above, the reality of the mental aspect of things, and the need to take seriously the view that we have the power, fallible as it may be, to make progress toward the truth about how reality is, about what is good, and about what is right and wrong. I also like his insistence that much is still unclear about how and why this is so. But to repeat, I think he's somewhat underplaying the potential involvement of evolution in an eventual understanding of these matters. He may also be underplaying something I think he laid more stress on in previous books, notably The View from Nowhere and the collection of papers and essays Mortal Questions: the degree to which there may be an irreconcilable tension between the "inside" and "outside" views of ourselves. However, his attitude here is to try to reconcile them. Indeed, one of the more appealing aspects of his worldview as expressed in both Mind and Cosmos and The Last Word is the observation that my experience "from inside" of what it is to be a reasoning subject, involves thinking of myself as part of a larger objective order and trying to situate my own perspective as one of many perspectives, including those of my fellow humans and any other conscious and reasoning beings that exist, upon it. It is to understand much of my reasoning as attempting, even while operating as it must from my particular perspective, to gain an understanding of this objective reality that transcends that perspective.
So far I haven't said much about the positive possibilities Nagel moots, in place of a purely biological evolutionary account, for explaining the origin of life, consciousness, and reason. These are roughly teleological, involving a tendency "toward the marvelous". This is avowedly a very preliminary suggestion. My own views on the likely role of mind and reason in the nature of reality, even more tentative than Nagel's, are that it is less likely that it arises from a teleological tendency toward the marvelous than that a potential for consciousness, reason, and value is deeply entwined with the very possibility of existence itself. Obviously we are very far from understanding this. I would like to think this is fairly compatible with a broadly evolutionary account of the origin of life and human consciousness and reasoning on our planet, and with the view that we're made out of physical stuff.
I think Nagel is quite aware of what you say he is not. Nagel is talking about a metaphysical conception of reduction, not as you appear to be, an epistemological one. Unfortunately he is no clearly that you are on the distinction and its import. I would suggest you check out William Seager's stuff on this, I think it is the best available. Also, Chalmers, with his own newly-labelled notion of reduction, "scrutability", but that is not pleasant reading.
Hi Benson Bear---
Thanks for this comment. I do think this is an important distinction (between metaphysical and epistemological reductionism), and one I wasn't making much of in this post. (Note that I don't actually say he's unaware of how non-reductive the "higher" sciences are at an epistemological level (i.e., the point about them needing to explain things in their own terms), but I do say he doesn't appreciate it sufficiently.) I'm not sure, though, whether Nagel is very clear about which he has in mind, or whether he doesn't mix the two. Aha, I guess you meant to say he is "no clearer than I am" on the distinction. Nagel does speak quite a bit about "reductionist explanation". And where he introduces the opposition between what he calls " "materialism" or "materialist naturalism" and "antireductionism" (on pp. 21-22), he characterizes the first of these by saying: "On the one side there is the hope that everything can be accounted for at the most basic level by the physical sciences, extended to include biology". "Can be accounted for" seems to me to smack of explanation, of epistemological reductionism. But I suppose you could read it as metaphysical ... as meaning "can be accounted for by some (probably nonexistent) omniscient being". (I would think the subjunctive would be more appropriate in that case, though...) I've looked back at the book quite a bit since writing this, and there are definitely places where it appears to be what I assume you mean by "metaphysical" reduction that worries him. (Metaphysical physical reductionism, that is, metaphysical reduction to the entities and laws of physics.) I'm still not sure that he doesn't conflate them to some extent.
Myself, I'm not so sure that metaphysical physical reductionism is as much of a problem as Nagel thinks for consciousness, mind, reason. (If he does think it's a problem, and I think some of his other thinking on mind---the stuff that smacks of "panpsychism"---suggests it is.) A dual aspect view, on which some structures realized in physical stuff have (real!) mental aspects, seems workable. But this may be because I'm more accepting of some kind of functionalism about the mental than is Nagel. Also, Nagel does seem to want consciousness, mind, even value, to have a role in explanation, for example of their own historical emergence, and of some of our behavior. One of his big worries about physical reductionism is that the kinds of explanations it is hoped that it [physical reductionism] will provide for e.g. the historical emergence of the phenomena we call consciousness, mind, value, will not be in terms of these concepts themselves, but will reduce them to other terms in a way that he thinks is so alien to the concepts themselves that it is extraordinary implausible to suppose it will ever happen. In other words, it seems to me that for Nagel, reductive explanation really is---or should be--- the worry much more than reductive ontology. Indeed, perhaps one of the main flaws of the book is to think that because the "materialist neo-Darwinian conception of nature" is committed to ontological (= metaphysical?) reductionism, it is committed to all the difficulties that go with epistemological reductionism.
In previous re-readings I had located some interesting places where it seemed to be ontological reductionism that concerned Nagel more than reductive explanation, but haven't relocated them at the moment. I'll point them out when I find them.
Chalmers seems to come up a fair amount in this connection, and I haven't read him, so perhaps will check him out, as well as Seager.