Topics Logic

Question As a young philosophy fanatic attempting to get to grips with the incumbent philosophical zeitgeist's obsession with logic as the source and answer to all its 'problems', I am having trouble finding any substantial reason for the unwavering authority and importance with which this analytic and logical character is treated within the whole of philosophical academia. Where is the incontestible evidence for such an incontestible reverence of such fundamental logical principles as the law of non-contradiction, other than within human intuition and common sense?

Accepted:
January 29, 2008

Comments

Before getting to your question, just an observation: all the philosophers I know believe that they should reason well and steer clear of contradiction, but I don't know any who think that logic is either the source of or the answer to all our philosophical problems.

In any case, I'm not sure what would do the trick here. If I'm going to give you "evidence" for the law of non-contradiction, then presumably I'm going to have to reason from the evidence. And I don't know how to reason to the conclusion that one thing is so rather than another unless I take it for granted that contradictions can't be true. Unless you already assume the law of non-contradiction, you could reply to any argument I give for it by saying "I agree it's also true that sometimes a statement and its denial both hold. And in particular, even though the law of contradiction is true, it's also false."

I don't really know what would count as "evidence" that the law of non-contradiction is true -- especially if I'm not allowed to appeal to something like "intuition" or self-evidence. But I'd gently suggest that you don't either. In fact -- as the remarks above are meant to suggest -- the "law of non-contradiction" doesn't really seem to be in the same category as laws of physics, for example. It's not a hypothesis that we might or might not find evidence for, nor one truth among many. I haven't the vaguest idea what it would mean to think that a proposition and its denial might both be true. (I do, of course, understand how it can be true when my brother says "I am in Canada" and also true when I say "I am not in Canada." But that's because what my brother is claiming isn't actually the denial of what I'm claiming.)

Here's a way to put the issue. If I take it to be up for grabs whether a proposition and its denial could both be true, what's left to constrain my reasoning? What would count as a good argument for or against anything? For my own part, I can't think of a good answer.

By the way: there are some amusing related reflections in Lewis Carroll's "What the Tortoise Said to Achilles." Have a look.