Worlds that aren't the Actual World

In this post i'm going to give a cursory introduction to possible worlds talk as it is relevant to my project, so that I have something to refer back to when relevant.

So there's this world. Take the world to be everything. That is, everything there is. Worlds aren't planets, they're whole realms of being. So everything that you think of as true is true of this world. Now take one of those truths...for instance, Joe Biden is vice president. Now, you might want to say that the proposition expressed by the sentence "Joe Biden is vice president" has interesting properties besides being true. It also has the property of being contingent. That is, it didn't have to be true, and that's an interesting difference between the proposition expressed by "Joe Biden is vice president" and "all triangles are trilateral".

Introducing Perspectives

So there's this world. There's some way the world is, just like there is some way your left leg is positioned right now. I'm sitting in a chair right now. That's one of the ways the world is.

There are sentences. Some of those sentences are true. It's plausible and intuitively appealing that the distinction between the sentences that are true and the sentences that are not true has something to do with the way the world is. It's an equally attractive thesis (though not equally plausible) that sentences are true when (and only when) the world is some way that matches the content of the sentence. For instance, my belief that there is a female philosopher is true because the world is built out of things, among them a philosopher that has the property of being female. In fact, you might think that all sentences are true (if they are true) in virtue of some corresponding bit of the world that makes them true. If you subscribe to the last thesis, you might espouse a correspondence theory of truth, according to which the world is full of truthmakers that suffice to make certain sentences true. Sentences, in turn, represent the world as being a certain way, and the true sentences are the ones that represent the world as containing their a truthmakers that the world does, indeed, contain.