How can we argue from logic to God’s existence?

I received a question about how logic implies God’s existence.  In order to help the respondent work through how the argument would work, I wrote out the mock exchange below:

Christian: It is inexplicable on atheism why the laws of logic describe the universe.  Why should a physicist with a blackboard be able to work out an equation using logic and have that equation describe the way the universe really is?  This is inexplicable on atheism, but Christianity can explain it for the universe was created by a rational mind.

Atheist: The laws of logic are necessary truths, so they should work in all possible worlds.

Christian: I completely agree with you, because I believe in God.  God exists in all possible worlds and so can ground the laws of logic in all possible worlds.  This makes the laws of logic necessarily true.  It remains inexplicable on atheism, however, why the laws of logic should work in any world much less in all possible worlds.

Atheist: Since the laws of logic are necessary truths, they don’t require any explanation.

Christian: That doesn’t seem to be how truth works.  If say, “the earth is the third planet from the sun,” then that statement is true because the earth really is the third planet form the sun.  In other words, any statement is true if it describes reality.  No statement can be true on its own, so even necessary truths depend on some reality in order to be true.  Christianity has a ready explanation, for the mind of God grounds logical truths in all possible worlds.  Atheism doesn’t seem to have such grounding.

Atheist: If God is a necessary being, then the laws of logic can be necessarily true.

Christian: I agree that both God and the laws of logic are necessarily true, but we don’t want to take that for granted.  Christians have the argument from contingency to show that God is a necessary being, and he also works as an explanation for why the laws of logic are necessarily true.  Atheism just doesn’t have the resources to explain why the laws of logic should be true in this way.

Atheist: Well fine, the laws of logic aren’t necessary truths.  Instead they are brute facts!*

Christian: Now you understand the problem for atheism.  Atheism can’t give any explanation for the laws of logic, you have to call them brute facts.  The Christian worldview, therefore, has greater explanatory scope since it does have an explanation for such things.  The Christian won’t even call God himself a brute fact, but as I have said we do have an explanation for his existence and an argument for why he exists that way.  The whole point I have been trying to make is that the laws of logic are inexplicable if atheism is true, and so you are quite right that there is no way to explain them if atheism is true; they are brute facts.  For these reasons the Christian worldview is a better explanation of reality than the atheistic worldview.

*I sometimes have people appeal to brute facts for moral truths, so I thought I’d include it here as I expect it to be an objection you may receive.  Brute facts are things that are true without any explanation at all.

Sincerely,

Matt Bilyeu


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