"But let us never forget, either, as all conventional history of philosophy conspires to make us forget, what the 'great thinkers' really are: proper objects, indeed, of pity, but even more, of horror."
David Stove's "What Is Wrong With Our Thoughts" is a critique of philosophy that I can only call epic.
The astute reader will of course find themselves objecting to Stove's notion that we should be catologuing every possible way to do philosophy wrong. It's not like there's some originally pure mode of thought, being tainted by only a small library of poisons. It's just that there are exponentially more possible crazy thoughts than sane thoughts, c.f. entropy.
But Stove's list of 39 different classic crazinesses applied to the number three is absolute pure epic gold. (Scroll down about halfway through if you want to jump there directly.)
I especially like #8: "There is an integer between two and four, but it is not three, and its true name and nature are not to be revealed."
I agree that the downvoting of this comment was overly harsh. My theory on why it occurred is different, and best illustrated by an example: if someone posted a comment saying "2+2=4 is only true in some contexts; in arithmetic modulo 3, 2+2=1", that comment would have been similarly downvoted.
However, let me be so bold as to say a word in defense of even that hypothetical commenter. Anyone mathematically sophisticated (including our downvoters) will agree that it is possible to construct a mathematical system in which 2+2 equals anything you like -- or, more precisely, for any symbol x, a system can be constructed in which the formula (string of symbols) "2+2 = x" is given the label "TRUE". Mod 3 arithmetic is an example for x = "1".
Now, it is at this point that the downvoters protest: "But this is not the same thing as saying 2+2=1! All you've done is change the meaning of the symbols in the formula, such as '2' and '1'. Two plus two is still four, for the original meaning of those words. You're confusing the map and the territory. Downvoted!"
Well, the downvoters do have a point. But, at the same time, let me suggest that they're also making the same mistake as our poor beleaguered commenter!
What they've done, you see, is to make a leap from "Ordinary (i.e. non mod-3, etc.) Arithmetic accurately models certain physical phenomena" to something like "Ordinary Arithmetic is true in (or of) the physical world". Instead of saying what they mean, which is "the physical world is best modeled by a system that has '2+2=4' as a 'TRUE' formula", they say "2+2 is in fact equal to 4".
Small wonder that confusion arises about whether mathematical statements are "emprical" or not! "The physical world is best modeled by a system that has '2+2=4' as a 'TRUE' formula" is clearly an empirical claim. But what about 2+2 = 4, all by itself? When a mathematician at a blackboard proves that 2+2=4 in Ordinary Arithmetic (or, for Eliezer's benefit, that infinite sets exist in standard set theory), has he or she made a claim about physics? No! Not without the additional assumption that the formal system being used is in fact an accurate map of the territory! But the mathematician makes no such assumption; he or she (acting as a mathematician) is interested only in the properties of formal systems. (Yes, that's right: I'm advocating the view known as formalism here. The other well-known positions in the philosophy of mathematics, namely Platonism and intuitionism, suffer from map-territory confusion!)
Mathematical systems, like Ordinary Arithmetic or Mod-3 Arithmetic, are part of the map, not the territory. The facts of mathematics are, so to speak, cartographic, rather than geographic.
In the OB post tautologies have to be empirically observed somehow, Eliezer writes about waking up one day and discovering all sorts of evidence that 2+2=3. This wouldn't be evidence that 2+2=3 in Peano arithmetic, it would be evidence that Peano arithmetic just doesn't apply for some reason. In my down-voted comment, I was just giving an example of how there can be different kinds of arithmetic if you are willing to be flexible about what arithmetic is. (If you are not willing to be flexible, then you are not willing to allow the observation that 2+2=3 as... (read more)