Wednesday, July 20, 2011

Possible Objection to the Kalam

The following is a question that came in to me recently, and I found it really interesting!

"To me, it seems logically possible that the sun could revolve around the earth. It's not a logical contradiction, therefore it's logically possible. But would it make sense for me to say that, in fact, it IS logically impossible for the sun to revolve around the earth given initial conditions of the universe? As long as the law of gravity is in play, it's logically impossible. (Now I guess we could say that using an inductive argument for gravity isn't very strong but still.)

Using this type of argument for minds, it's logically possible that a unembodied mind exists. However, via induction (the only minds we know to exist has bodies) it's logically impossible for an unembodied mind to exist in THIS universe. (Just like it's logically impossible for the sun to revolve around the earth in THIS universe).

Now I know the KCA gives us 3 good reasons to think that the cause of the universe is an unembodied mind, so I think that an inductive argument fails because of that (that's the type or argument I would use to counter this). But what would you say to such an argument?"

Your last paragraph is sufficient to defeat any attempted claim such as the one above. But I would like to amend the definition of what is logically possible: a proposition or state of affairs is logically possible given that it is internally coherent (is not a self-contradiction) and does not violate a necessary truth.

Now, given the laws of physics and gravity and the like, I only see how the statement "the sun revolves around the earth" is physically impossible. For consider: the statement is still not self-contradictory, and the truth, "the laws of physics and gravity exist" has not been shown to be necessarily true (only contingently). Now let's dig further into the objection, just for fun.

Suppose one replies, "yes, but perhaps we can frame the argument this way: 'The law of nature is X, the sun revolving around the earth is not-X. The law of nature is X is true. Therefore, it is necessarily false that the sun revolves around the earth, or not-X."

The problem is that this commits a well-known (and difficult to master) modal logic fallacy. It takes the form of this:

1. Either P or not-P.
2. Not (P and not-P).
3. P.
4. Therefore, necessarily P.
5. Therefore, necessarily not (not-P).

Plug in anything you like for the values "P" and "not P" that makes sense. In short, if this were valid, then literally every truth would demand the necessary falsehood of its opposite. But in that case, there just is no possible world in which that opposite exists. This means that literally everything that is, was, or will be must be, and could not be otherwise. I hope that alone is enough to show its fallacious. A simpler way of saying it is to say that just because a certain proposition is true, it only follows that its negation is false; but it doesn't follow the negation is necessarily false (in the modal sense).

What that means for us is that given the laws of nature, all that follows is that it is not the case that the laws of nature do not exist; not that it cannot. What is impossible is the composite state of affairs of both being true. So this would not be a good objection to lodge against the kalam at all, for its major premise cannot get off the ground, being fallacious.
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