Do you? Hi, I'm Peter Adamson, and you're listening to the History of Philosophy podcast, brought to you

with the support of King's College London and the Lever Hume Trust online at www. History of Philosophy.

Net. Today's episode, Nobody's Perfect, the Stoics on knowledge.

When we last left our hero Chrysippus, he was grappling with two formidable opponents, the

soritees paradox and the liar paradox.

To remind you, the soritees goes like this.

I ask you whether one grain of sand is a heap of sand.

You say no.

So I ask about two grains, then three, and so on.

As soon as you admit that the threshold has been reached so that we finally have a heap of

sand, I say, that's ridiculous. Adding one grain of sand can't turn the amount into a heap. A variation

which touches on a sensitive spot for me personally, asks you to imagine plucking hairs off of

a man's head one at a time until he becomes bald.

It's absurd to suppose that one hair could make the difference, yet he surely becomes bald at some point.

It's a cute little paradox, but does it rise to the exalted level of being philosophy?

As it turns out, this puzzle and others like it provoke a lot of excitement among philosophers

nowadays. They raise the issue of vagueness. There are certain concepts which seem to have no sharp boundaries like bald and

heap as the puzzle illustrates. Those are, if you'll pardon the expression, particularly clear

cases of vagueness, but they are far from the only ones.

Think for instance about evolution.

Apes turn slowly into humans generation by generation.

Is it any easier to say which generation separates

...