In my first post on Brad Delong's series of criticisms of Thomas Nagel's new book Mind and Cosmos I focused not on Brad's initial critcism but on a later post that seemed to be implying Nagel put too much weight on "common sense".  In this post I'll focus on Brad's initial criticism, and in particular on what seems to me his misunderstanding of Nagel's arguments concerning reason, as crucially dependent on the notion that reason is infallible at least in some cases.

Brad's critique began with a reaction to some remarks by Tyler Cowen, in particular Cowen's assertion that "People will dismiss his [Nagel's] arguments to remain in their comfort zone, while temporarily forgetting he is smarter than they are and furthermore that many of their views do not make sense or cohere internally."

Now I think it is unfortunate that Cowen is speculating about who's "smarter than" who, and unfortunate that Brad joins him in doing so.  Everyone involved seems to be quite smart, but unfortunately Brad seems to me to be misunderstanding what the main thrust of Nagel's argument is, and where its main weakness lies.  DeLong reacts to Cowen:

And here Tyler appears to me to have gone off the rails. Thomas Nagel is not smarter than we are--in fact, he seems to me to be distinctly dumber than anybody who is running even an eight-bit virtual David Hume on his wetware.

He fixates on a single example taken from Nagel's book and, I think, fails to understand the role Nagel thinks this example plays. Brad seems to think it is crucial that Nagel view reason as infallible. "And my certainty that I know must be correct!" as he puts it in his gloss on Nagel:

Nagel's argument, to the extent that I understand it and that it is coherent, goes roughly like this:

Suppose we think we are going south-southwest and see the sun rising before us. We don't think: "the heuristics of reasoning that have evolved because they tend to boost reproductive fitness conclude that it is very likely that I am not in fact going south-southwest". We think, instead: "I know that the sun rises in front of me when I am going east! Either I am hallucinating, or I must be going roughly east! I deduce this by my reason, and my reason is a mechanism that can see that the algorithm it follows is truth-preserving! My mind is in immediate contact with the rational order of the universe! I don't just think I am going east! I know I am either hallucinating or going east! And my certainty that I know must be correct! And I know that my certainty must be correct--and that triumph of reason cannot be given a purely physical explanation! Since I believe I am not hallucinating, I abandon the belief that I am going south-southwest because of my reason's transcendent grasp of objective reality! My consciousness is an instrument of transcendence that grasps objective reality! And no blind evolutionary process can produce such a transcendent instrument!"

Aspects of this example of Nagel's bothered me as well, but it plays a much less central part in Nagel's book than you might think from Brad's gloss. Note that even the material in quotes is a gloss, not a quote from Nagel, although it draws fairly heavily on him. (Further down in this post, I quote the passage in Nagel from the first appearance of the example to the last explicit reference to it.  Brad's post also contains further material on the general topic of reason directly quoted from Nagel.)  In the context of Brad's post, the term "Nagel's argument" seems to imply that this is the main argument of the book, on which it stands or falls.

As I said, I don't think the example is central. Rather, it is intended as an example of something central to the book, which is the claim that reason has the power --- imperfect and fallible, to be sure --- to get us in touch with objective reality, in a way that helps us transcend the appearance of things from our own particular viewpoint or perspective. It is probably also intended as part of a discussion of how logic --- the avoidance of contradiction --- is an essential part of our ability to engage in more subtle and substantive forms of reasoning. I will discuss this second point later, concentrating for the moment on the first.

Nagel is extremely clear that he does not believe that reason's power to help get us in touch with objective reality is infallible. (See the next quote I display from Nagel for an utterly explicit statement of this.)  It may seem that he is claiming it to be infallible in driving example, but even if he is, that does not seem crucial to his main line of argument. Most of Brad's ridicule of Nagel's argument is directed against the claim of infallibility, so it just misses its target if by "Nagel's argument" is meant, as is clear from the context, the overall line of argument of Nagel's book.

The overall argument of the book is not a single line of reasoning. But some main strands concern the nature and origin of life, of consciousness, and---what is under discussion here----of reason. Here is how Nagel puts his main argument concerning the nature of reason:

Thought and reasoning are correct or incorrect in virtue of something independent of the thinker's beliefs, and even independent of the community of thinkers to which he belongs. We take ourselves to have the capacity to form true beliefs about the world around us, about the timeless domains of logic and mathematics, and about the right thing to do. We don't take these capacities to be infallible, but we think they are often reliable, in an objective sense, and that they can give us knowledge. [Mind and Cosmos, pp. 80-81]

Perhaps some confusion has arisen because of Nagel's use of the word "reliable" elsewhere in the book (e.g. in the excerpt DeLong quotes)...it should not be taken to imply infallibility. In Brad's favor, the "directness" with which Nagel says reason "puts us in touch with the rational order of things" in this particular example, is thought by Nagel to strengthen his case. I just don't think it's the main point.

Lest anyone misunderstand, I don't agree with Nagel that our understanding of reason as part of a process enabling us to --- fallibly, Nagel admits, and partially, I might add --- get in touch with an objective reality that transcends each of our particular perspectives on it, provides support to the view that reason could not have evolved through natural selection.

Brad goes on to propose a counterexample to the claim that the bit of reasoning in Nagel's example is infallible. It is that "During northern hemisphere winter, if you are near the North Pole, it is perfectly possible to see the sun rise due south if you are due solar north of the center of the earth as you come out of the Earth's shadow. And I was. And I did."

Several things can be said about this. The most important one is that Nagel need not and does not claim infallibility. Less important is that Nagel explicitly described his example as one in which "I am driving...". Brad was flying. So Brad's "it happened to me" is not literally true. Moreover the distinction between flying and driving is not an irrelevant one (like that between its being Nagel or DeLong who is doing the reasoning...) but one that is probably relevant. I don't know whether there are any roads near enough the north pole that one could, driving, have the experience Brad did. Perhaps there is land, or at certain times of the year, perhaps there is still enough sea ice, near enough the pole that one could do this off-road, by driving a long way off-road, or bringing a vehicle in by air. Or perhaps not. I really don't think it matters much. There are some background assumptions that are not made explicit, though suggested by the framing of the situation, as there are in most pieces of reasoning.

Here's Nagel's introduction of the example, and its sequel:

But suppose I observe a contradiction among my beliefs and "see" that I must give up at least one of them. (I am driving south in the early morning and the sun rises on my right.) In that case, I see that the contradictory beliefs cannot all be true, and I see it simply because it is the case. I grasp it directly. It is not adequate to say that, faced with a contradiction, I feel the urgent need to alter my beliefs to escape it, which is explained by the fact that avoiding contradictions, like avoiding snakes and precipices, was fitness-enhancing for my ancestors. That would be an indirect explanation of how the impossibility of the contradiction explains my belief that it cannot be true. But even if some of our ancestors were prey to mere logical phobias and instincts, we have gone beyond that: We reject a contradiction just because we see that it is impossible, and we accept a logical entailment just because we see that it is necessarily true.

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. Something has happened that has gotten our minds into immediate contact with the rational order of the world, or at least with the basic elements of that order, which can in turn be used to reach a great deal more. That enables us to possess concepts that display the compatibility or incompatibility of particular beliefs with general hypotheses. We have to start by regarding our prereflective impressions as a partial and perspectival view of the world, but we are then able to use reason and imagination to construct candidates for a larger conception that can contain and account fo that part. This applies in the domain of value as well as of fact. The process is highly fallible, but it could not even be attempted without this hard core of self-evidence, on which all less certain reasoning depends. In the criticism and correction of reasoning, the final court of appeal is always reason itself.

What this means is that if we hope to include the human mind in the natural order, we have to explain not only consciousness as it enters into perception, emotion, desire, and aversion but also the conscious control of belief and conduct in response to the awareness of reasons---the avoidance of inconsistency, the subsumption of particular cases under general principles, the confirmation or disconfirmation of general principles by particular observations, and so forth. This is what it is to allow oneself to be guided by the objective truth rather than just by one's impressions. It is a kind of freedom---the freedom that reflective consciousness gives us from the rule of innate perceptual and motivational dispositions together with conditioning. Rational creatures can step back from these influences and try to make up their own minds. I set aside the question whether this kind of freedom is compatible or incompatible with causal determinism, but it does seem to be something that cannot be given a purely physical analysis and therefore, like the more passive forms of consciousness, cannot be given a purely physical explanation either.

If I decide, when the sun rises on my right, that I must be driving north instead of south, it is because I recognize that my belief that I am driving south is inconsistent with that observation, together with what I know about the direction of rotation of the earth. I abandon the belief because I recognize that it couldn't be true. If I put money into a retirement account because the future income it generates will be more valuable to me than what I could spend it on now, I act because I see that this makes it a good thing to do. If I oppose the abolition of the inheritance tax, it is because I recognize that the design of property rights should be sensitive not only to autonomy but also to fairness. As the saying goes, I operate in the space of reasons.[Mind and Cosmos, pp. 91-92]

Gene Callahan criticizes Brad as follows:

So Nagel gives us two beliefs:
1) The sun rises in the east (where I am); and
2) I am driving south, which means the east will be on my left.
And a fact: But the sun is rising to my right!

So Nagel's point is that we cannot continue to hold 1) and 2) simultaneously: "I must give up at least one of them." How could he have said that more plainly?

Then Nagel goes on to state that "IF" (notice, that "if" is right in the original text, I did not add it!) he decides to give up belief 2), it will be because he sees he cannot logically hold 1) and 2) at the same time. Notice what the "if" implies: Nagel clearly understands that he has the option of giving up belief 1) instead! Otherwise, no point to the "if."

Now, Brad Delong comes along and says, "What an idiot! [And he really does insult Nagel like that.] Once, I was in that situation, and I had to give up belief 1)!"

Ahem. One does not disprove the proposition that one ought to give up at least one of two contradictory beliefs by showing how once, one gave up one of two contradictory beliefs.

Brad's response:

Nagel does not believe: "the sun rises in the east (where I am)." Nagel believes: "the sun rises on my right".

Thus the two beliefs that Nagel's reason tells him are in conflict are (a) his belief that he is going south, and (b) his belief he sees the sun rising on his right. The choice he gives himself is between concluding that he is going north and concludeingthat he is hallucinating.

Now I understand that Callahan wishes that Nagel were not Nagel but rather some Nagel' who had added a third belief: (c) "I am in a normal place (but there are weird places on earth where the sun rises in a non-standard way)."

But we go to argument with the Nagel we have, and not the Nagel' Callahan wishes we had.

Callahan would presumably say that Nagel was just being sloppy, and that there is actually an unsloppy Nagel' who had made the argument that Callahan wishes he had made, and whose reason does have transcendental access to objective reality, and that we should deal with the argument not of Nagel but of Nagel'.

But Callahan's confusion of the Nagel' he wishes we were talking about with the Nagel who we are talking about demonstrates my big point quite effectively: powerful evidence that Nagel is a jumped-up monkey using wetware evolved to advance his reproductive fitness, rather than a winged angelic reasoning being with transcendental access to objective reality. No?

I think Callahan is roughly right here. Roughly because it's not obviously correct that "Nagel gives us two beliefs". Callahan's (2) is stated in Nagel's parenthetical introduction of the example (see the quote above). But the parenthetical introduction is probably best read as describing the situation, not explicitly attributing beliefs ("I am driving south", not "I believe I am driving south"). It's clear we're to take as implicit that the subject of the example believes this, though, and when Nagel returns to the example later in the passage I quoted it is made explicit: this is the belief that is given up. That return to the example also makes it clear that there are background beliefs not initially mentioned in Nagel's parenthetical introduction of the example: Nagel mentions "what I know about the direction of rotation of the earth". This is presumably where Callahan gets number (2) namely "The sun rises in the east (where I am)." That seems a correct reading of Nagel, so DeLong's "Nagel does not believe: "the sun rises in the east (where I am)." Nagel believes: "the sun rises on my right"." just seems wrong.  The Nagel of the example believes both of these things (if we understand "the sun rises on my right" to mean something like "the sun is rising on my right".  Brad's misinterpretation is probably based on taking the parenthetical sentence introducing the example as a statement of the two beliefs that are in contradiction, rather than a sketch of a situation in which "I observe a contradiction in my beliefs". (Brad also changes Nagel's "driving south" to "going south", which affects, as I discussed above, whether Brad's flying experience is relevant.)

I think Nagel is getting at several things with this example, in light of the surrounding discussion.

(1) One is the idea that deductive reason helps us access truths about the world that go beyond our own particular perspective on it, because the avoidance of inconsistency is integral to the use of language, which in turn enables us to describe how the world is or might be from a point of view that is not just the perspective of one being that it makes possible. I am not sure what Brad means by "transcendent access" to objective reality--- it may just be a rhetorical flourish, liked "winged" and "angelic". The term "transcendent access" does not appear in Mind and Cosmos. When Nagel uses words with the root "transcend", he is referring to transcending a limited point of view to come up with a view of the world "as it is independently of the thinker's beliefs and even independently of the community of thinkers to which he belongs." (He also uses it---probably in the same sense---to refer to "a transcendent being", a notion he finds unappealing.) In his description of "what it is to be guided by the objective truth" toward the end of the long quote above, he is quite clear that this involves observations and (broadly speaking) "inductive" reasoning ("confirmation and disconfirmation"), and earlier he mentions "imagination" in addition to reasoning. (So if Brad's "Humean heuristics" just means inductive reasoning broadly construed, then it looks like Nagel's on board with it.) When reading the discussion of the driving example in Mind and Cosmos and related passages in The Last Word, I have sometimes felt puzzled about why Nagel seems to be laying such emphasis on deductive reasoning. And in general, I'm slightly frustrated by the relative lack of discussion of induction or related non-inductive aspects of scientific reasoning in Nagel's writings. But I think the quoted passages make clear that for Nagel, reason comprises induction too. I think the reason for his stress on deduction and consistency is the importance --- as Nagel sees it --- of language, and language's intimate link with logic --- to the very formulation of theories and hypotheses, scientific and otherwise. Nagel's emphasis on "directness" in simple cases may or may not be misplaced, but I don't think it's the linchpin of his broader argument.

(2) Secondly, and perhaps more controversially, Nagel believes that we must conceive of our reasoning as autonomous and free---that we cannot view it as a mere disposition. A mere disposition is how Hume, on one reading, viewed "induction", if not deduction... here I think Nagel would disagree with Hume, and perhaps with DeLong, if "mere disposition" is what DeLong means by "Humean heuristics". The key point, for Nagel, is that "In the criticism and correction of reasoning, the final court of appeal is always reason itself." The theory of evolution itself is part of that objective picture of reality, transcending our individual perspectives on it, that reason enables us to arrive at. For Nagel, it would be absurd to let a belief in evolution by natural selection undermine our view that our reasoning, in conjunction with imagination and observation, can get us in touch with and is getting us in touch with objective reality, because our very belief in evolution itself relies on this view. It is this, and not infallibility or "transcendent access" (a term Nagel never uses) that is the most important, and that I think is crucial to his broader argument.  Note that this does not automatically imply that a belief in evolution by natural selection cannot modify our assessment of our reasoning, perhaps leading us to view particular judgments or modes of reasoning as suspect, because arising from heuristics that we can see to be reliable only in certain situations similar to those in which they evolved.  Indeed, Nagel seems overly impressed with this possibility---one of his main grounds for rejection of the notion that there could be an evolutionary-biological explanation of the advent of reason in humans is his view that such an explanation would necessarily undermine our assessment that the reasoning we exercise in conjunction with our other faculties actually is, on balance, tending to get us in touch with objective reality.

Brad does address some of these issues, in response to Callahan's pointing out that they are the main ones; I will take up that part of their discussion in a later post.

Let me here take up an element of the quoted passage from Nagel that is bound to have raised some hackles.
Nagel: "I set aside the question whether this kind of freedom [to decide what to believe and how to act for reasons, i.e. by reasoning -- HB] is compatible or incompatible with causal determinism, but it does seem to be something that cannot be given a purely physical analysis and therefore, like the more passive forms of consciousness, cannot be given a purely physical explanation either."

This really is a key argument for Nagel. However, in my view, it needs to be understood in terms of the subtleties of emergence. As I have written elsewhere, I think there is some crucial unclarity in Nagel (or in my understanding of him) about what "purely physical explanation" might mean. If it means "explanation in terms of the concepts of physics" then I suspect that the hypothesis that "this kind of freedom [...] cannot be given a purely physical explanation [...]" is correct.  (However, I think I still have a substantive disagreement with Nagel on the meaning of "explanation".)   But if we allow an evolutionary biological evolution to use concepts like "reason" (which seems rather reasonable if one is going to try to explain the origin of our ability to reason), it seems to me that this is compatible with our eventually having an evolutionary-biological explanation of its historical origin. Here also I think I disagree with Nagel, who sometimes refers to "physics extended to include biology", suggesting that to him an evolutionary-biological explanation is a kind of purely physical explanation. I've discussed this some in my first post on Mind and Cosmos, and will discuss it more in future posts. There are deep and subtle philosophical and scientific questions involved, but in my view it is here if anywhere that Nagel goes importantly astray in dealing with reason, and not primarily in some actual or putative attribution of infallibility to simple judgements of contradiction, nor even in the notion (which Nagel does appear to subscribe to, but which I'm not sure I want to endorse) that the faculty of avoiding contradiction involves our minds being in "immediate contact with the rational order of things" [Mind and Cosmos, p. 91].