This is the weekly Q & A blog post by our Research Professor in Philosophy, Dr. William Lane Craig.


Dr. Craig,

I cannot thank you enough for your philosophical and theological work. Your work and Reasonable Faith is a constant encouragement and motivation to me as a Christian. In a unit on German philosophy (in a specific section on Leipniz), I recently had my German 3 class translate, discuss and respond to your argument, "Gott ist die beste Erklärung warum überhaupt etwas existiert," from your debate with Ansgar Beckermann. Your argument provoked a reaction and interest I was not expecting.

Here is my question: Why do you not employ the laws of logic as evidence for the existence of God? It seems to me that God (a necessarily existing mind) is the best explanation for the laws of logic in a similar way that he (a necessary personal being of moral perfection) is the best explanation for certain necessary moral truths. Am I mistaken about logic as evidence for the existence of God? Is there a reason the laws of logic should not be used in an argument similar to your argument from objective moral values and duties?

Thank you for your time and help.



United States

Dr. William Lane Craig’s Response

Dr. William Lane Craig

Wow, I never expected my debate with Beckermann would become the basis for German lessons! What a great way to teach the language!

I do believe that just as God is the basis of necessary moral truths, so He is the basis for the laws of logic, like the rules of inference. The laws of logic merely describe the way God thinks. As the supremely rational being, God’s thinking is always logical. The rules codify how He thinks.

The problem is that I don’t know how to argue for this conviction. Taking the moral argument as our pattern, we might argue as follows:

1. If God did not exist, the laws of logic would be merely human conventions.

2. The laws of logic are not merely human conventions.

3. Therefore, God exists.

This argument is valid and its second premiss is indisputably true. Any attempt to take the laws of logic as just human inventions is bound to assume the laws of logic themselves and so to be self-defeating.

But I don’t know how to argue for premiss (1). I think it’s true, but I don’t know how to show that it’s true. How could you show that on atheism, (pq) and p do not imply q? Unlike the case with objective moral values and duties, you can’t even appeal to many atheists who deny the laws of logic. About the best spin I could put on (1) is to say that grounding logic in God is part of a synoptic theistic or Christian view of reality which makes eminently good sense. One thinks of C. S. Lewis’ famous aphorism: “I believe in Christianity as I believe that the sun has risen: not only because I see it, but because by it I see everything else.”

So I’ve not bothered to look into the question further. I hope there’s an argument to be made here, but I’ll leave it to others to discover.

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