Phil 340: Possibility and Imaginability (Part 3 of 3)

When we were thinking about examples of things that might be metaphysically possible or impossible, we raised the question:

When philosophers talk about “definitions,” they distinguish between:

• conceptual definitions: these are what you need to know, at least implicitly, to understand the term and think thoughts that we’d express with it. For example, to understand the term “square,” you need to know that squares have four sides.
• scientific identities or definitions: these are things like “Water is H₂O,” “Cows are animals with genetic code GACCTAGCTA,” and so on.

Some of the examples of impossibilities we discussed in class seem like they’d only need to violate a scientific definition, not a conceptual definition. For example, it doesn’t seem to be part of the conceptual definition of water that it be H₂O. But arguably it wouldn’t be possible to have water without having H₂O. It doesn’t seem to be part of the conceptual definition of being you that you be made of flesh and blood and bones rather than snow. But arguably it wouldn’t be possible for you to be made of snow.

We’ll consider some more examples of this as we proceed.

Cases of supervenience also supply examples where we seem to have metaphysical impossibilities that aren’t just unpackings of a conceptual definition.

For instance, perhaps we’d want to say that how beautiful a painting is supervenes on how paint is distributed on its canvas. If so, then it would be metaphysically impossible for two paintings to have the same layout of paint, but differ in how beautiful they are. That layout of paint would fix or metaphysically determine that the painting is beautiful. But we’d be hard-pressed to come up with a definition of beauty in terms of how much, and what colors, of paint are at each spot on the canvas. You can hold that beauty-facts supervene on the paint-facts even if you think we’re not able to define “beauty” in terms of how the paint is distributed.

In class, I gave a more complex example where we can get metaphysical impossibilities that aren’t just the result of conceptual definitions.

1. To begin, we need to distinguish between claims about language and claims about the world.

   Suppose there are two women, Beverly and Helen. And suppose I’m madly in love with Beverly, but she doesn’t know I exist. Helen on the other hand is in love with me, but I don’t like Helen. What I want is to be loved by Beverly. How could I get what I want?

   Would getting Helen to change her name to “Beverly” help me get what I want? Of course not. Even if Helen changed her name, she would still be Helen, and Beverly would still be Beverly. It doesn’t matter what names we call them. What I want is to be loved by a certain person, Beverly, not just to be loved by somebody or other whose name is “Beverly.”

   Similarly, a stone would still be a stone, even if there were no people. It would still be a stone even if no one used the word “stone” to talk about it. It would still be a stone, though it would not be called “a stone.” It would still be a stone, even if people called it by other words, like “dog.”

2. “Jim Pryor” is a name for me, the person I actually am. Now, could I fail to be Jim Pryor? Well, there might be possible situations in which I have a different name, and so in which I’m not called “Jim Pryor.” There might be possible situations in which other people are called “Jim Pryor.” But I’m not interested in those situations. I’m not interested in what people might be called.

   Nor am I interested in the question whether I might inhabit a different body; or whether I might live a different life (for example, becoming a spy instead of a philosopher).

   “Jim Pryor” is a name for a particular person, not a name for some human body or biography. What I want to know is: could there be any possible situations in which I’m not that person? Any situations in which that person, Jim Pryor, the person who is actually called “Jim Pryor,” is somebody other than me?

   It does not seem like there could be. For there to be such a situation, I would have to be somebody other than the person I actually am. And that is not possible. The person I am can not possibly be identical to something other than himself.

   It may be possible for me to live somebody else’s life, and to be called by somebody else’s name. For instance, perhaps I could have lived the life of Napoleon, and have been called “Emperor Napoleon,” instead of “Jim Pryor.” But even if that were to occur, and I experienced all the events of Napoleon’s life, it would still be me, this person, Jim Pryor, the person who is talking to you right now, experiencing them.

   So now we have one result:

   It is not possible for me to be somebody other than Jim Pryor, the person I actually am. It is not possible for me to exist without Jim Pryor’s existing.

3. And yet, in certain circumstances, I would be able to imagine or conceive of myself existing, while disbelieving that I am Jim Pryor, and even while imagining that Jim Pryor does not exist. For instance:

   Suppose I get amnesia, and forget my name. I think that Jim Pryor is somebody else. I hear bad things about Jim Pryor and so I decide to kill him. I think, “The world will be such a better place, with me in it but with Jim Pryor no longer existing.” Isn’t that imagining myself existing without Jim Pryor’s existing?

   So our second result is:

   In certain circumstances, I might imagine or conceive of a world in which I exist but Jim Pryor does not.

   I can conceive of such a world, but as said a moment ago, such a world is not genuinely possible. Hence, the mere fact that I can conceive of something does not guarantee that that thing is genuinely possible.

   Many philosophers used to think that if you can conceive or imagine something without confusion or contradiction, that proves that it’s possible.

   Some historical philosophers raised doubts/objections about this; but a good many philosophers thought it was true.

   When we introduced Descartes’ argument in his Sixth Meditation, we talked about one of Arnauld’s Objections. Arnauld argued that the mere fact that Descartes can conceive of a situation in which he exists but has no body does not show that such a situation is really possible. Perhaps Descartes is ignorant of certain facts about his nature. Perhaps it really is part of his nature to have a body — he’s really just a body that thinks. It’s just that he doesn’t know this fact about himself. That’s why he can imagine or conceive of himself existing without any body. Not because it really would be possible.

   Nowadays, philosophers realize that you have to be more careful. There is no contradiction in the amnesiac professor’s conception of himself existing but Jim Pryor’s not existing. At least, there is nothing there that goes against any conceptual definitions he has for “I” or “Jim Pryor.” He knows how to use those terms perfectly well, and no amount of pure reasoning or logic will enable him to figure out that they name the same person.

   So the fact that you can conceive or imagine something without any conceptual contradiction can at best be some reason or evidence that the thing is possible. It can’t be an absolutely certain proof. Some things can be conceived of that are not possible, but rather necessarily false. One only manages to conceive them because one is ignorant in certain ways. They are necessarily false, but one does not know that they are false.

   The case of the amnesiac professor is an example of that. The amnesiac professor does not know that he is Jim Pryor. So he does not know that wherever he goes, there Jim Pryor goes. It’s nonetheless necessary that wherever he goes, there Jim Pryor goes. What’s necessary and what’s possible for him depends on which object he is. It does not depend on what people (or he himself) know about him.

Philosophers say that something is knowable a priori when it’s possible for one to know it, by reasoning alone. For instance, the fact that 1+1=2 is knowable a priori. We say that something is knowable a posteriori when it’s only possible to know it by relying on one’s senses, and/or doing empirical investigation and research. For instance, the fact that Charlotte is not in Virginia is knowable only a posteriori. So too is the fact that it’s sunny outside right now, and the fact that Romeo and Juliet was written by a man.

Our example of my being the same person as Jim Pryor is another case of something which is knowable only a posteriori. If one does not already know that Jim Pryor and I are the same person, no amount of reasoning alone will enable one to ascertain that this is the case. One would have to do some empirical observation, investigation, and research to find out whether Jim Pryor and I are one person or two.

Yet, as we said, the fact that I am identical to Jim Pryor is metaphysically necessary. So this fact is necessary but knowable only a posteriori. We call it an example of the necessary a posteriori.

Work on these kinds of examples is very important these days in philosophy of language and philosophy of mind. It’s also very important for our thinking about the relation between the mind and the body. For recall Descartes’ argument. One step in that argument has the form:

1. If I can conceive or imagine something without confusion or contradiction, then that thing is at least metaphysically possible.
2. I can clearly conceive of a world in which I exist but my body does not.
3. So it must be possible for me to exist without my body.

If that argument were sound, then so too should this argument be sound:

1. If I can conceive or imagine something without confusion or contradiction, then that thing is at least metaphysically possible.
2. [Suffering from amnesia] I can clearly conceive of a world in which I exist but Jim Pryor does not.
3. So it is possible for me to exist without Jim Pryor.

But as we’ve just seen, the second argument is not sound. Its first premise is false. So Descartes’ argument must not be sound either. The mere fact that he can conceive of himself (or his mind) existing without his body does not show that it is genuinely possible for the one to exist without the other.

Descartes’ conclusion may be correct: it may be that his mind and body are really distinct things, which could possibly exist independently. But the mere fact that Descartes can conceive of his mind existing without his body doesn’t prove that that is really possible.

In light of our discussion from the past few classes, we can see that there’s room here for the materialist to object. He can say: “Hey, whether we are able to imagine or conceive of something is only a fallible guide to whether that thing really is possible. For all the dualist has shown, this might be one of the cases where you can imagine something, but it’s really not possible.”

Trying to determine which of the things we can conceive/imagine really are possible, and which aren’t, is a very challenging problem in contemporary debates about the mind/body problem.

I know that everything which I clearly and distinctly understand is capable of being created by God so as to correspond exactly with my understanding of it. Hence, the fact that I can clearly and distinctly understand one thing apart from another is enough to make me certain that the two things are distinct, since they are capable of being separated, at least by God...