Good on you! as we say in New Zealand. And just remember, its Xmas time again!

I am assuming you are the author of the entertaining Crimes Against Logic. I have used it as a stocking stuffer!

It is interesting to speculate about how the nature of the interactions we have whilst building our minds limits the type of reasoning we can do. I am not sure if Steve is saying that there are no limits, as once we have acheived reason it can theoretically take us anywhere.

As for Nagel, he is talking crap. “conscious minds and their access to the evident truths of ethics… ” ??? Anyone who uses that line is to be treated with a great deal of suspicion.

The interesting question is whether our knowledge of logic shows that “the materialist, neo-Darwinian conception of nature is almost certainly false” (the subtitle of Nagel’s book). I have not read the book; I know only the quoted passage from Gene Callahan’s (sympathetic) post:

“I see that the contradictory beliefs cannot all be true, and I see it simply because it is the case. I grasp it directly.”

How Nagel gets from here to his sub-title, I do not know (because I have not read the book, sorry). But this passage makes me think that he is relying on a linguistic trick. The idea that some kind of non-physical interaction (between logical facts and minds) is occurring here arises from his use of the word “because” (which suggests causation) and “grasps”, which also suggests some kind of contact.

Let me describe the situation in a way that gives rise to no such suggestion of non-physical causation. I am sitting behind a veil and, on the other side, someone is tossing a coin. I am asked to say whether each toss lands heads. If my success rate, over the long run, is 0.5, we will feel no need to posit any mechanism of apprehension. I do not apprehend. If I get a long run success rate well above 0.5, then we may start hypothesizing about extra-sensory perception and so on. It is precisely because people cannot do better than 0.5 in these circumstances that most of us do not believe in ESP.

Now suppose that the probability of the outcome I am being asked about from behind the veil is 1, perhaps because it is logically certain. Suppose, for example, that I am told that a number of quadrupeds will be brought to the other side of the veil and I must say which of them have four legs. Even if I have a 100% success rate, no one will believe that some kind of weird non-physical apprehension is going on, that I am getting the answers right because I am “grasping” the features of the quadrupeds behind the veil.

You may wonder how come I understand that all quadrupeds have for legs or, more generally, you may wonder how I reason logically, but the answer does not require me to be “seeing” what is behind the veil. Can a Darwinian explain how come human minds (not all of them always!) are apt to reason in accordance with modus ponens, modus tollens, etc.? I think it can.

Once you have a physical or Dawinian explanation of our logical abilities, combined with the necessity of logical and mathematical truths, you are going to find it difficult to create a case for non-physical apprehension or non-physical causation from the fact that we know logical facts.