I haven't been too impressed by "The Stone," which is The New York Times' online philosophy forum. Nonetheless, I'm glad a major newspaper is devoting space to philosophy, whose lack of media coverage these days makes poetry look like Jersey Shore by comparison. Also, today's column contains a gem of a paragraph by Timothy Williamson, who is calling into question the coherency of naturalism (defined here as a philosophy that treats the hard sciences as the most reliable source of knowledge).
We can formulate the underlying worry as a sharp argument against the extreme naturalist claim that all truths are discoverable by hard science. If it is true that all truths are discoverable by hard science, then it is discoverable by hard science that all truths are discoverable by hard science. But it is not discoverable by hard science that all truths are discoverable by hard science. “Are all truths discoverable by hard science?” is not a question of hard science. Therefore the extreme naturalist claim is not true.
This is a nifty little logic trick, but, I think, not merely a play of words. It's more akin to a Zen koan, those self-cancelling (literally, I suppose) thought puzzles. It also reminds me of something I learned in Modern Western Philosophy (i.e. Descartes through Kant) back in my undergraduate days: The popular sentiment "Everything is subjective" cannot be true, since it is, in fact, an objective statement. That is, in order to be true, it has to prove itself false. "Everything is subjective" presents itself as an objective statement. Angst-ridden freshman don't like this.