|Raphael, The School of Athens|
“I Know, Because the Caged Bird Sings: Plato’s Theaetetus.”
Script for podcast (aired Feb 28 2011) by Peter Adamson
‘“Now, I know what you’re thinking: this will be easy. Just point to a thermometer, which tells us an objective fact about how cold the air is. But not so fast. Firstly, Protagoras can agree with your kids that whatever the thermometer says, it’s up to each of us to say whether it is cold or warm for us. Secondly, he can point out that the thermometer is itself something you perceive. If it seems to you that the thermometer reads, say, 30 degrees, then it’s true for you that the thermometer reads 30 degrees. It’s true for you simply because you perceive it to be the case. To insist on there being an absolute truth about the reading of the thermometer is to assume that there is a truth independent of any perceiver, and that’s what Protagoras denies: man is the measure of all things, right?
“But Socrates has a couple of other tricks up his sleeve. He starts with abuse: wouldn’t it be just as true to say that a pig or a baboon is the measure of all things? Abuse is always satisfying, of course, but this argument doesn’t carry much weight. Fortunately he has more philosophically satisfying points to make too. For instance, on this “man is the measure” doctrine, there’d be no point consulting experts: why pay to go to the doctor if you are just as good a measure as the doctor is? If it seems to you that taking aspirin will cure that nasty bout of appendicitis, then it’s true for you! This sounds like a theory that will reduce the life expectancy of its adherents - reason enough to reject it. Closely related is an objection about predicting the future: if I expect to recover from my illness, then it will be true for me that I will recover; if it then later seems to me that I’m still sick, then it will seem to me that I have not recovered, and so it will be true for me that I didn’t recover. It’s hard to see how both of these could be the case.
“But Socrates’ most interesting objection illustrates a classic, perennially useful philosophical maneuver. Whenever you’re presented with a bold new theory – especially a skeptical theory – ask whether the theory could be true on its own terms. For example, if someone says that nothing is true, you can ask him whether this claim is itself true. Or if someone says that language is meaningless, you can ask him how he is able to convey this idea in a sentence. In the same way, Socrates suggests that Protagoras’ relativism doctrine is self-refuting. For, even if Protagoras agrees with the doctrine, Socrates does not. Thus it will be true for Socrates that Protagoras’ doctrine is false. Indeed, since this follows from Protagoras’ doctrine, it will even be true for Protagoras that for Socrates the doctrine is false. Thus Protagoras is bound by his own doctrine to admit that his doctrine is false. But maybe this trick is a bit too tricky: even if Protagoras has to admit that the doctrine is false for Socrates, he doesn’t have to admit that it’s false in itself or really false. Remember, according to him, there’s no such thing as something’s just really being false or true. There is only something’s being false or true to you, to me, to Socrates.
“Before we get any dizzier, let’s leave relativism behind and move on to another major theme of this dialogue: the possibility of false belief. This theme arises when Theaetetus accepts that knowledge is not after all perception, and makes another suggestion. Perhaps knowledge is having a true belief. After all, when I know something I have a belief about it, and obviously it can’t be a false belief. So why not say I know something when I have a true belief about it? All well and good, says Socrates, but if we want to uphold this definition we need to understand how it could be that some beliefs are true, and others false. And here we will run afoul of those pesky sophists again. Some sophists suggested that it is impossible to say or believe anything false - in which case everything is just a matter of persuasion. This challenge appears in several Platonic dialogues; we’ve already seen it arising in the Euthydemus. But the Theaetetus is again probably the most famous case. The argument here for the sophistical view is rather reminiscent of Meno’s paradox, which we looked at last time. It goes like this: either I know something or I don’t. If I know about it, then I won’t make a mistake about it, thanks to my knowledge; but if I don’t know about it, then I can’t think about it, so I won’t be able to make a mistake then either. In other words, I’ll have either perfect knowledge of each thing, or no knowledge of it at all, and in neither case will I get things wrong. So, it’s impossible to make a mistake, to believe anything false.
“Notice that this solves the sophistical dilemma: I can make a mistake about something because in a way I know it, and in a way I don’t. I know who Buster Keaton is, because I must have got acquainted with him to have an impression of him in my memory. But this doesn’t guarantee that I’ll be error-free in identifying people as Buster Keaton. This is a compelling analogy, and for once the proposal isn’t exactly rejected in the dialogue. Rather, the characters realize that even if it works for cases of mistaken identity in perception, there are many cases of false judgment where it will not help. For instance, what is going on when I add seven and five and get eleven? There’s nothing here about impressions being made on our memory by perception, and yet I’ve still made a mistake. So Socrates produces another image in place of the wax tablet. Imagine, he says, that your soul is like an aviary, a birdcage, with lots of birds flying around in it, each of which represents a piece of knowledge. Whenever you’ve learned something, you’ve acquired a bird and put it into your aviary. What happens when you add five to seven and get eleven is that you reach into your aviary and pull out the eleven bird instead of the twelve bird. Again, your knowledge of eleven actually enables you to make the mistake, the way your knowledge of Buster Keaton enabled you to mistake Charlie Chaplin for him.
“So where does all that leave us? Right back where we started: without a general account of false belief, but still thinking that maybe knowledge is the same thing as true belief. Ah, but it isn’t, says Socrates. Just consider the case of a jury: they might be persuaded by some fancy lawyer that a certain man is innocent of a crime. And the man really is innocent. But we wouldn’t say that the jury knows, since they only believe this because the lawyer was slick enough to persuade them. Thus they have a true belief, but not knowledge. So much for that definition. Yet Theaetetus still feels - and today’s epistemologists tend to agree - that knowledge must have something to do with true belief. Maybe knowledge is true belief plus something else as well... something the jurors are lacking, but which you would have if you were, say, an eye-witness at the murder and know that the accused man is innocent.
|James P. Morse, Reality and the Mind|