Topics Logic

Question If God is omnipotent then surely he can do anything!? My intuition tells me he can defy logic because surely he created it. I know philosophers will then ask me if it is possible for God to create a world where it both doesn't rain and rains at the same time. I am then forced to say that of course this doesn't seem possible. But...this leaves me with two questions: (a) Why do philosophers always have to talk about 'possible worlds'!? (b) Surely a world of contradictions only seems implausible to us because we are reasoning from the knowledge and experience we have in this world. We can't conceive of such ideas as not raining and raining at the same time because we are bound by the logic of this world.

Accepted:
November 13, 2005

Comments

Some philosophers agree with you that God created logic. Descartes, I believe, had a view like that. But most philosophers (I think!) believe that omnipotence only implies that God can do anything that is metaphysically possible. And it's not possible to make it rain and not rain at the same place at the same time (except when it drizzles; but leave that aside).

I should mention that some philosophers (e.g., Graham Priest, JC Beall) have formulated a kind of logic that allows some contradictions to be true. So far, this has not become a popular position.

(a) Philosophers talk about possible worlds as a way to make vivid various possibilities. Some philosophers (like David Lewis) take (nonactual) possible worlds to be concrete objects, just like the actual world. Many other philosophers take (nonactual) possible worlds to be just ways that the actual world might have been. If you understand possible worlds in the latter way, possible worlds are heuristically useful--but you are not committed to holding that there really exist such things.

(b) This is an interesting observation. Nonreligious philosophers have recently argued that whether or not we can conceive of something has nothing to do with its metaphysical possibility. Philosophers of religion have traditionally thought that we cannot really conceive of God's infinite attributes. Maimonides, a medieval Jewish philosopher-theologian, thought that we can know nothing about God; and Thomas Aquinas, a medieval Christian philosopher-theologian, held that our language does not literally apply to God, but applies only "analogically."

You are probably right about our limited conceptual powers, but it doesn't follow that God could make "a world of contradictions." If such a world is beyond our ability to conceive of it, does the expression "a world of contradictions" make sense? You're in deep waters here!

On (a), I might add that possible worlds are an extremely useful tool. As Lynne mentioned, there are many different ways to understand what they are supposed to be. For many purposes, however, one can simply regard possible worlds as a certain kind of mathematical construct. The reason they are then so useful is that they allow us to understand, in a precise way, the logic of such expressions as "necessarily" and "possibly". In fact, there are many notions of necessity and possiblity, and their logics can be very different. Perhaps more importantly, though, possible worlds help us to get a grip on so-called "counterfactual conditionals", like "If JFK had not been assassinated, the US would not have become as seriously involved in Vietnam".

It might interest you to know that, even before "paraconsistent" logics came on the scene—these are the logics that allow contradictions to be true...and, of course, false—logicians were interested in logics of necesssity and possibility that allow "It is necessary that A" and "It is necessary that not-A" both to be true. In such logics, the inference "It is necessary that A; therefore A" has to fail, unless the logic is paraconsistent. One such logic is, arguably, what one gets by considering moral necessity or, better, moral obligation. One way to get a clean formal account of such logics is to allow, alongside the possible worlds, also impossible worlds!