There was an interesting letter in the TLS last week from the philosopher Thomas Nagel. Nagel was responding to a letter in the previous week's issue from Stephen Fletcher, a member of the chemistry department at Loughborough University. Fletcher had complained that Nagel recommended Stephen C Meyer's Signature in the Cell in the TLS's Books of the Year round-up.

Meyer's book presents what he describes as a "radical and comprehensive new case" for intelligent design, one that apparently reveals "the evidence not merely of individual features of biological complexity but rather of a fundamental constituent of the universe: information". According to Fletcher,

"Intelligent Design" is of course a code phrase to obscure a malicious and absurd thesis; namely, that a supernatural being has interfered in the evolution of life on this planet. If Nagel wishes to take this notion seriously, very well, let him do so. But he should not promote the book to the rest of us using statements that are factually incorrect.

I haven't read Meyer's book, nor am I competent to assess Fletcher's contention that Nagel simply got the science wrong when he wrote, in his gloss of Signature in the Cell, that "Meyer takes up the prior question of how the immensely complex and exquisitely functional chemical structure of DNA, which cannot be explained by natural selection because it makes natural selection possible, could have originated without an intentional cause". In any case, it's the second paragraph of Nagel's letter that caught my eye:

The tone of Fletcher's letter exemplifies the widespread intolerance of any challenge to the dogma that everything in the world must be ultimately explainable by chemistry and physics. There are reasons to doubt this that have nothing to do with theism, beginning with the apparent physical irreducibility of consciousness. Doubts about reductive explanations of the origin of life also do not depend on theism. Since I am not tempted to believe in God, I do not draw Meyer's conclusions, but the problems he poses lend support to the view that physics is not the theory of everything, and that more attention should be given to the possibility of an expanded conception of the natural order.

The idea that atheism somehow entails a sort of materialistic reductionism, according to which all worldly phenomena can be wholly and exhaustively explained in physical terms, is controversial. It certainly requires more argument than people like Fletcher, or Richard Dawkins, for that matter, tend to provide. This is a point that Nagel made in his review of Dawkins's bestselling The God Delusion back in 2006:

The fear of religion leads too many scientifically minded atheists to cling to a defensive, world-flattening reductionism. Dawkins, like many of his contemporaries, is hobbled by the assumption that the only alternative to religion is to insist that the ultimate explanation of everything must lie in particle physics, string theory, or whatever purely extensional laws govern the elements of which the material world is composed . . . We have more than one form of understanding. Different forms of understanding are needed for different kinds of subject matter. The great achievements of physical science do not make it capable of encompassing everything, from mathematics to ethics to the experiences of a living animal. We have no reason to dismiss moral reasoning, introspection, or conceptual analysis as ways of discovering the truth just because they are not physics.

The point is that you don't have to be a theist to think that physics has a tough job accounting for phenomena such as conscious experience. Though if you believed Dawkins and his epigones, philosophers have long since resolved the puzzle of why that soggy lump of grey matter inside our skulls should give rise to anything so extraordinary as consciousness.

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