Aristotle: …but then how would you tell me about this at all? If there’s no change then how do you speak, expect to change my mind, or even tell the difference between your premises and your conclusion?
Parmenides: This is a completely false dilemma. Just because something is not real does not mean it has no explanatory role to play. In fact, a non-existent thing might even be necessary to our thought. Have you ever heard of ideal gases, black boxes, average number of children, the sunrise and sunset, or a thousand other such things? Change is certainly necessary to our thought, just as a moving sun is necessary to our perception. But this does not require us to say that such things really exist. There’s more than one sense of “is” – sometimes it only involves knowing what we mean, and seeing an explanatory value in something, but without asserting that such a thing exists in fact.
A: Yes, let’s talk about these different senses of “is”. If I say “I’m going out to buy coffee”, then whatever I buy is coffee, right?
A: But I can either buy beans or a drink, correct?
A: So one sense of “is” involves what can be something, another involves what actually is something.
A: But this is the whole problem with your argument. You say “if something comes to be, it comes to be either from what is or what is not. But not from the first, for then it does not come to be; and not from the second, for nothing comes from nothing.” But you overlook that “is” has two senses. The end result is actually, and it comes to be from what is potentially.
P: So change, on this account, is from the possible per se.
P: And something either is possible or not?
A: I think that’s right.
P: But then all you’ve done is blown squid ink and shifted the goal posts back. “The possible”, whatever this is, is not exempt from the law of either existing or not existing. If you want possibility to be, then you’re asserting a unity with what you call act, and precisely as unified it cannot come to be. If you want possibility not to be, you assert some unity with non-being, and as such it cannot give rise to anything. All of your arguments just seem like clever ways to talk yourself out of the principle of contradiction, and to assert some magical tertium quid between what exists and what doesn’t. This is, as far as I can tell, all your “potential being” comes to. You yourself in your writings say that it might just as well be potential privation or non-being.
A: But this is just how we find the world. On the one hand, it’s clear that impossible things do not exist, and so by the principle of contradiction we must say that possible things exist. On the other hand, future things clearly don’t exist, but they are possible. We understand possibility as in one sense existing and in another sense not.
P: Maybe we do, just as we understand all sorts of fictional things. But we know that something can’t be such a thing. If you really want to spin what is necessary for your thought into reality, then why don’t you extend the same privilege to the principle of contradiction? Isn’t that far more necessary for your thought? Your whole argument is question begging anyway, since I deny any reality to temporal things anyway. They are all doxa – that is, things that arise from the fact that we know the world, but do not and cannot exist in it. And it’s not as if I deny them arbitrarily – I’m just following out the consequence of the obvious principle that a thing either exists or it doesn’t.
A: Right, a thing is what exists or not. But we’re not talking about things but the sources that give rise to things. Possibility is, of itself, a source of a thing and not a thing.
P: But if you want to make this break you have to – again for what seems like the thousandth time – break the universality of either existing or not. What use is it to assert some world of “pure sources” if we can’t even relate it to the world we know? You repeatedly insist on “being-non-beings” or “thing-non-things” in order to prove me wrong. If this is what you need to refute me, I’m pretty confident in what I think.
Here’s what I think our disagreement really comes down to: you want nature to be just as intelligible and scientific as our understanding of being and non-being. True, if nature is perfectly intelligible then there has to be some domain of “possible being” with a ghostly existence, and the various exigencies of thought have to find purchase in the real world – like when we call a possible thing the thing itself. But I say this is not science but dialectical opinion.