Sunday, December 21, 2008

Aristotle on Opposites 3: Possession and Deprivation

In the Categories 10, Aristotle outlines 4 kinds of opposites. In the last two posts, I covered the first two of these, namely 'correlatives' and 'contraries'. The third kind of opposites is possession and deprivation: possessing some feature that one should naturally have is the opposite of being deprived of it.

For example, sight and blindness are opposites in this way for animals, because animals naturally have the ability to see. When an animal can see, it possesses sight, but when it's blind, it's deprived of sight.

It's important to note that this only applies to natural features that things are supposed to have. We don't normally say that stones are blind, because stones aren't supposed to see. Only things that are supposed to have sight can be deprived of it, so sight/blindness are opposites for animals, but not stones, foot stools, and so on.

(To put this another way, being deprived of something is not the same as simply not having it. Stones don't have sight, but they're not blind. The sentence 'x is deprived of F' does not mean 'x does not have F'.)

Aristotle also says that possession and deprivation always refer to one thing that either possesses or is deprived of some natural feature. When we talk about sight and blindness and opposites, we're not talking about one animal that can see as the opposite of another animal that's blind. We're talking about the same animal either having sight or being blind. Sight/blindness are opposites for that one animal, not multiple animals.

This distinguishes possession/deprivation from correlatives. As I explained two posts back, correlatives always hold for two things, and they're reciprocal (if one thing is 'double', then another is 'half'). Possession/deprivation are not like this. If one thing can see, there's no guarantee that another is blind. If only one animal existed, it could still either see or be blind, and sight and blindness would still be opposites for that animal.

It's tempting to think that possession/privation are opposites in the way that contraries are. As I explained in the last post, contraries are the most different features that belong to the same kind (so 'white' and 'black' are contraries for color, 'hot' and 'cold' for temperature, and so forth). After all, what could be 'more different' than having some feature vs. not having it? But Aristotle says possession/deprivation are not contraries, and here are the reasons he gives.

Contraries are either (i) necessary and binary, or they are (ii) unnecessary and not binary. Possession/deprivation are binary, for something either has a natural feature or it doesn't. An animal can either see, or it's blind, but it can't be somewhere in between. (An animal might have poor sight, as I do, but I can still see. And sometimes an animal's sight is so bad that it is, for all intensive purposes, blind.) And the fact that possession/deprivation are binary rules out the possibility that possession/deprivation could be unnecessary contraries, for as I explained in the last post, no binary pair are unnecessary contraries.

But possession/deprivation aren't the same as necessary contraries either. Necessary contraries are such that one or the other of the pair must always be present in the appropriate sort of thing. But animals don't always have either sight or blindness. When animals are undeveloped (like when they're zygotes), they can't see yet. Still, at that time, they're not deprived of sight, for they aren't supposed to see yet. So although possession/deprivation are binary, they're not necessary in the way that binary contraries must be.

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