December 12, 2008

The well-known simile

SOCRATES: Do my account the favor of supposing that our souls contain a slab of wax. This slab varies in size, purity and hardness from individual to individual, and in some cases its consistency is ideal.
THEAETETUS: So I shall suppose.
SOCRATES: Let us go on to say it is a gift from Mnemosyne, mother of the Muses, and that it works like this: of all we see or hear or think of on our own, we lay the slab beneath those thoughts and perceptions we wish to remember and create an impression, just like the seals we stamp with signet-rings. Whatever is imprinted, we hold in our memory and our knowledge as long as its image holds, but what is washed away or is impossible to imprint becomes forgotten and unknown.
     ....Knowing you and Theodorus, I retain in that waxiness signs for both of you, as if left by signet-rings. Now when from far off I get an indistinct view of you together, I strive to tally a particular sign against a particular sight, and to make it fit the trace of its own imprint. But in my rush I fumble my attempt at recognition, and match the sight of one to the other's sign, as when people bind their sandals to the wrong feet. You could also compare it to what happens in a mirror, when right and left trade places and confound the sight. By this type of error, judgment is parted from the truth and rendered false.
THEAETETUS: A very likely account, Socrates, and a marvelous description of what can happen to our judgment.
SOCRATES: Besides this there occurs the case where, knowing you both, I perceive one of you but not the other, and my knowledge of the other is not in accordance with my perception of him. When I described it like this previously you did not understand me.
THEAETETUS: I sure didn't.
SOCRATES: Earlier [at 192b], I was saying that one man who knows another and perceives him and holds his knowledge of him in accordance with his perception would never confuse him with a third man he knows and perceives, as long as his knowledge of the third man was also held in accordance with his perception. Was that not it?
SOCRATES: Now I'm talking about about what went missing from that account. It's the case in which we say false opinion arises: when, knowing two men and seeing them both (or perceiving them by some other means), we fail to hold the sign of each in accordance with the perception, and like a poor archer straying from the target we get it wrong. And this is what we call falsity.
THEAETETUS: Quite fairly.
SOCRATES: So any time a sign is met by its corresponding perception but another sign corresponding to an absent perception gets fastened to it, thought is deceived. By this account (if what we are saying is correct), it is impossible to be deceived or judge falsely about things unknown and never perceived. Rather, it is about the things we know and perceive that judgment turns and darts in its alternation between falsity and truth: true when it aligns the proper stamps precisely with what made them, and false when it gets them crooked and aslant.

Theaetetus 191c-e, 193c-194b