Welcome to Defenders, the teaching class of Dr. William Lane Craig, today and excurses

on Natural Theology, Part 24.

For more resources from Dr. Craig, go to reasonablefaith.org.

Last time we introduced the concept of possible worlds in order to help us better understand

the ontological argument for God's existence.

And I emphasize that possible worlds are not any sort of concrete object, a planet or a universe, the easiest way to think about a possible

world is just as a list of statements, a sort of massive conjunction, P and Q and R and S and so on, so that this massive conjunction includes every proposition or its opposite,

and thus it yields a maximal description of reality.

Nothing is left out. And that's what a possible

world is. It's just sort of a maximal description of reality. And reality could have been

different ways. So different descriptions will make different possible worlds.

For example, P and not Q and not R and S and so on.

Or you could have, so we'll label that in W1 and this will be W2.

Here's W3.

That could be say say, not p and Q and R and not S and so on. W4, yet another world.

Could be not p and not Q and not R and S and so on, so that you have various descriptions

of the way the world could have been.

And the description which has only true conjuncts,

that is to say the description, every conjunct of which is true,

will be the description of the actual world.

That will be the true description that will be the actual world.

So what the ontological argument wants to do is to show that if God's existence is possible, if God exists in one possible world, then he exists

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