Nagel and DeLong I: Common Sense

Brad DeLong has been hammering --- perhaps even bashing --- away at Thomas Nagel's new book Mind and Cosmos (Oxford, 2012).  Here's a link to his latest blow. I think Nagel's wrong on several key points in that book, but I think Brad is giving people a misleading picture of Nagel's arguments.  This matters because Nagel has made very important points --- some of which are repeated in this book, though more thoroughly covered in his earlier The Last Word (Oxford, 1997) --- about the nature of reason, defending the possibility of achieving, in part through the use of reason, objectively correct knowledge (if that is the right word) in areas other than science, and giving us some valuable ideas about how this can work in particular cases, for example, in the case of ethics, in The Possibility of Altruism [Princeton, 1979].

In his latest salvo Brad suggests that "If you are going to reject any branch of science on the grounds that it flies in the face of common sense, require[s] us to subordinate the incredulity of common sense, is not based ultimately on common sense, or is a heroic triumph of ideological theory over common sense--quantum mechanics is definitely the place to start…".  This is preceded by some quotes from Nagel:

  • But it seems to me that, as it is usually presented, the current orthodoxy about the cosmic order is the product of governing assumptions that are unsupported, and that it flies in the face of common sense…
  • My skepticism is… just a belief that the available scientific evidence, in spite of the consensus of scientific opinion, does not… rationally require us to subordinate the incredulity of common sense…
  • Everything we believe, even the most far-reaching cosmological theories, has to be based ultimately on common sense, and on what is plainly undeniable…
  • I have argued patiently against the prevailing form of naturalism, a reductive materialism that purports to capture life and mind through its neo-Darwinian extension…. I find this view antecedently unbelievable— a heroic triumph of ideological theory over common sense…

Now there are things I disagree with here, but Nagel is clearly not claiming that no theory that is not itself a piece of common sense is acceptable. Indeed, the second bullet point makes it clear that he allows for the possibility that scientific evidence could "rationally require" him to subordinate the incredulity of common sense. It is his judgment that it does not in this case. Now---at least with regard to the possibility of an explanation by evolutionary biology of the emergence of life, consciousness, and reason on our planet and in our species, which is what I think is at issue--- I don't share his incredulity, and I also suspect that I would weigh the scientific evidence much more heavily against such incredulity, if I did share some of it.  But Nagel is not commited to a blanket policy of "reject[ing] scientific theories because they fail to match up to your common sense." Regarding the third bullet point, it's perhaps stated in too-strong terms, but it's far from a claim that every scientific theory can directly be compared to common sense and judged on that basis. The claim that scientific theories are "ultimately based in common sense and on what is plainly undeniable" does not imply that this basis must be plain and direct. Logic and mathematics develop out of common-sense roots, counting and speaking and such... science develops to explain "plainly undeniable" results of experiments, accounts of which are given in terms of macroscopic objects... Some of this smacks a bit too much of notions that may have proved problematic for positivism ("plainly undeniable" observation reports?)... but the point is that common sense carries some weight and indeed is a crucial element of our scientific activities, not that whatever aspect of "common sense" finds quantum theory hard to deal with must outweigh the enormous weight of scientific experience and engineering practice, also rooted "ultimately" according to Nagel in common sense, in favor of that theory.

Just for the record I don't find that the bare instrumentalist version of quantum theory as an account of the probabilities of experimental results "flies in the face of common sense" --- but it does seem that it might create serious difficulty for the conception of physical reality existing independent of our interactions with it. At any rate it does not seem to provide us with a picture of that sort of physical reality (unless you accept the Bohm or Everett interpretations), despite what one might have hoped for from a formalism that is used to describe the behavior of what we tend to think of as the basic constituents of physical reality, the various elementary particles or better, quantum fields.  But if someone, say Nagel, did believe that this all flies in the face of common sense, it would be open to him to say that in this case, we are permitted, encourage, or perhaps even required to fly in said face by the weight of scientific evidence.

As I've said, I disagree on two counts with Nagel's skepticism about an evolutionary explanation of mind and reason: it doesn't fly in the face of my common sense, and I weigh the evidence as favoring it more strongly than does Nagel. Part of my disagreement may be that what Nagel has in mind is an evolutionary explanation that is commited to a "reductive materialism that purports to capture life and mind through its neo-Darwinian extension." Whereas I have in mind a less reductive approach, in which consciousness and reason are evolutionarily favored because they have survival value, but we do not necessarily reduce these concepts themselves to physical terms. In my view, biology is rife with concepts that are not physical, nor likely to be usefully reduced to physical terms--- like, say, "eye". As with "eye", there may be no useful reduction of "consciousness" or "perception" or "thought" or "word" or "proposition", etc.., to physics, but I don't think that implies that the appearance of such things cannot have an evolutionary explanation. (Nor, just to be clear, does it imply that these things are not realized in physical processes.) So I might share Nagel's incredulity that such things could have a "materialist" explanation, if by this he means one in terms of physics, but not his incredulity about evolutionary explanations of the appearance of mind and reason. To me, it seems quite credible that these phenomena form part of the mental aspect of structures made of physical stuff, though we will never have full explanations for all the phenomena of consciousness and the doings of reason, in terms of this physical structure.

(David Deutsch's recent book The Beginning of Infinity is one excellent source for understanding such non-reductionism---see in particular its Chapter 5, "The Reality of Abstractions".)

I'll likely make several more posts on this business, both on other ways in which I think Brad and others have mischaracterized Nagel's arguments or misplaced the emphasis in their criticisms, and on why this matters because some important points that Nagel has made on matters closely related to these, that I think have value, are in danger of being obscured, caricatured, or dismissed under the influence of the present discussion by Brad and others.

Thomas Nagel's "Mind and Cosmos"

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.

My short review of David Deutsch's "The Beginning of Infinity" in Physics Today

Here is a link to my short review of David Deutsch's book The Beginning of Infinity, in Physics Today, the monthly magazine for members of the American Physical Society.  I had much more to say about the book, which is particularly ill-suited to a short-format review like those in Physics Today.  (The title is suggestive; and a reasonable alternative would have been "Life, the Universe, and Everything.")   It was an interesting exercise to boil it down to this length, which was already longer than their ideal.  I may say some of it in a blog post later.

It was also interesting to have such extensive input from editors.  Mostly this improved things, but in a couple of cases (not helped by my internet failing just as the for-publication version had been produced) the result was not good.  In particular, the beginning of the second-to-last paragraph, which reads "For some of Deutsch’s concerns, prematurity is irrelevant. But fallibilism undermines some of his claims ... " is not as I'd wanted.  I'd had "this" in place of "prematurity" and "it" in place of "fallibilism".  I'd wanted, in both cases, to refer in general to the immediately preceding discussion, more broadly than just to "prematurity" in one case and "fallibilism" in the other.  It seems the editors felt uncomfortable with a pronoun whose antecedent was not extremely specific.  I'd have to go back to notes to see what I ultimately agreed to, but definitely not plain "prematurity".

One other thing I should perhaps point out is that when I wrote:

Deutsch’s view that objective correctness is possible in areas outside science is appealing. And his suggestion that Popperian explanation underwrites that possibility is intriguing, but may overemphasize the importance of explanations as opposed to other exercises of reason. A broader, more balanced perspective may be found in the writings of Roger Scruton, Thomas Nagel, and others.

I was referring to a broader perspective on the role of reason in arriving at objectively correct views in areas outside science. "More balanced" was another editorial addition, in this case one that I acquiesced in, but perhaps I should not have as some of its possible connotations are more negative than I intended.  "Appealing," though not an editorial edition, is somewhat off from what I intended.  I wanted also to include suggestion of "probably correct" since something can be appealing but wrong, but couldn't find the right word.  I shortened this discussion for reasons of space, but I had initially cited Scruton specifically for aesthetics, and recommended his "On Beauty", "Art and the Imagination", and "The Aesthetics of Architecture".  I haven't read much of his work on politics (he is a conservative, although from what I have read a relatively sensible one at the philosophical level) nor his "Sexual Desire", so don't mean to endorse them.  Likewise I had initially recommended specifically Nagel's "The View from Nowhere" and "The Last Word", and was not aware of his recent "Mind and Cosmos"; I emphatically did not mean to endorse his skepticism, in that book, about evolutionary explanations of the origins of life and mind, although I do think there is much of interest in that book, and some (but certainly not all!) of the criticism of it that I've seen on the web is misguided.  I am much more in sympathy with Deutsch's views on reductionism than with Nagel's:  both are skeptical about the prospects for a thoroughoing reduction of mind, reason, and consciousness to physical terms, but Nagel, bafflingly, seems to think that an evolutionary explanation of such phenomena is tantamount to such physical reductionism.  Deutsch seems to me more sophisticated about the nature of actual science, and how non-reductionist many scientific explanations are, and about how that can nevertheless be compatible with physical law.  I should say, though, that I am less sympathetic than Deutsch is to accounts of mind and consciousness as being essentially a computer running a certain kind of program.  I view embodiment, interaction with a sufficiently rich environment, and probably a difficulty in disentangling "hardware" and "software" (perhaps related to Douglas Hofstadter's notion of "strange loops") as likely to be crucial elements of an understanding of mind and consciousness.  Of course it may be that with a sufficiently loose notion of "kind of computer program" and "kind of input" some of this could be understood in the computational terms Deutsch seeks.

Thoughts on the evolution of technology-using intelligence

A few more thoughts inspired by Tim Maudlin's remarks in an interview with the Atlantic magazine. I'll quote Tim again first:

The question remains as to how often, after life evolves, you'll have intelligent life capable of making technology. What people haven't seemed to notice is that on earth, of all the billions of species that have evolved, only one has developed intelligence to the level of producing technology. Which means that kind of intelligence is really not very useful. It's not actually, in the general case, of much evolutionary value. We tend to think, because we love to think of ourselves, human beings, as the top of the evolutionary ladder, that the intelligence we have, that makes us human beings, is the thing that all of evolution is striving toward. But what we know is that that's not true. Obviously it doesn't matter that much if you're a beetle, that you be really smart. If it were, evolution would have produced much more intelligent beetles. We have no empirical data to suggest that there's a high probability that evolution on another planet would lead to technological intelligence. There is just too much we don't know.

Certainly it is remarkable that only one technology-using (if you discount a few cases of the most rudimentary use of natural objects, and perhaps a few cases of very rudimentarily modified objects, as tools by other animals) species has evolved on Earth. An interesting question is whether most planets that do evolve life eventually evolve species that produce and use complex technology, and how many such species. My guess, certainly not supported by long consideration, but by a modest amount of offhand thought, is that given enough time, they do. My guess is also that it takes a fair amount of time for evolution to produce such a species, and that this is part of an overall evolution towards increasing complexity, in some sense I'll here leave ill-defined, of the overall web of life on the planet, and in particular, of the most complex species on the planet. (Perhaps the notions of complexity explored by Charles Bennett, Murray Gell-Mann, and Seth Lloyd may be relevant.) Since the environment in which organisms must survive and propagate evolution consists in significant measure of other organisms, evolution itself creates new niches in this environment for organisms to evolve toward filling. As Robinson Jeffers wrote:

What but the wolf’s tooth whittled so fine
The fleet limbs of the antelope?
What but fear winged the birds, and hunger
Jewelled with such eyes the great goshawk’s head?

While I don't see a clear and obvious argument for it offhand, it is plausible to me that this process tends over time to create more and more complexity. In this sense, I suspect there is "progress" in evolution, despite a fair amount of scoffing in some quarters at the notion of evolutionary progress. This looks like a fruitful area for research. It's also plausible that this sort of evolutionary progress may eventually create both a niche for, and an accessible evolutionary path towards, a technology-using intelligent species. Whether the fact that we have only a single such species on this planet is due primarily to their being essentially only one niche for such a species, to the fact that it takes a long time for such a species to evolve due to the many precursor steps necessary (this would need to be a rather tricky anthropic argument, I suspect), or just happenstance, seems even more speculative, but very interesting.

So it seems to me I find myself supporting, at least speculatively, what may seem the naive, knee-jerk view "that the intelligence we have, that makes us human beings, is the thing that all of evolution is striving toward". With allowance for a metaphorical use of "striving", and modification of the definite article ("the thing"), I'm not too unhappy with that characterization. How far things go beyond "the intelligence we have", though, I'm not prepared to say. And it may be that there are very different paths for a planetary ecosystem to take, other than the production of one (or a few?) technology-using species. As Tim says, in the end we really don't know. But I do think there is interesting knowledge to be sought here.

Tim Maudlin on the training of physicists, the evolution of intelligence, and more

I had to link this interview with philosopher Tim Maudlin, in the Atlantic, when I read his observation that "The asking of fundamental physical questions is just not part of the training of a physicist anymore." But there's a lot more of interest in the interview as well. I found the article via Andrew Sullivan's blog; Sullivan found Tim's thoughts on the evolution of intelligence to be particularly interesting:

What people haven't seemed to notice is that on earth, of all the billions of species that have evolved, only one has developed intelligence to the level of producing technology. Which means that kind of intelligence is really not very useful. It's not actually, in the general case, of much evolutionary value. We tend to think, because we love to think of ourselves, human beings, as the top of the evolutionary ladder, that the intelligence we have, that makes us human beings, is the thing that all of evolution is striving toward. But what we know is that that's not true. Obviously it doesn't matter that much if you're a beetle, that you be really smart. If it were, evolution would have produced much more intelligent beetles. We have no empirical data to suggest that there's a high probability that evolution on another planet would lead to technological intelligence. There is just too much we don't know.

Indeed there is, but it points out some very interesting questions: is there a tendency, given enough time, for a species intelligent enough to produce technology to arise on an earth-like planet? Is there, perhaps, a tendency for it to inhibit the evolution of other such species? My personal guess (and it's just that, a guess, not supported by careful thought) is that there is such a tendency, but it takes a lot of time, it builds on, and is part of, a slow increase in the complexity of the most complex organisms. This is, of course, probably the "knee-jerk" view. Whether it inhibits the evolution of other species is something I'm less willing to speculate on (though if Neanderthals were another such species, we may have some evidence (one case!) for inhibition of the branching of a potentially technologically-capable intelligent species into two such species). Whether vertebrates have characteristics making it more likely for them to evolve technologically-capable intelligence than it is for, say, insects to evolve it is another interesting question.