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


Hey Dr. Craig,

Firstly, I would like to congratulate you on the brilliant and elegant new website. The change to a mobile-friendly platform definitely makes your content and ministry much more accessible.

Secondly, I had a question about the Contingency argument. You say in defense of premise 2 of your formulation of the Leibnizian contingency argument that the support for the contingency of the universe is that the contingent truth "the universe exists" could have been false or different without any logical contradictions which lends substantial credibility to the contingency of the universe. This obviously is true and no rational seeker of the truth can deny because the truth "All wives are married women" is necessary because it being false or different would entail logical contradictions. For example, if the truth "wives are married women" was false it would mean that would mean that the truth "wives are unmarried women" would be true which entails a logical contradiction so the original proposition "wives are married women" is a necessary truth. That seems fair. However, when we apply the same analytic criteria to the truth "God exists", I see no logical contradictions if the truth was false or different. Does this not make God a contingent truth rather than a necessary one?

You could say that God is by definition necessary and thus it does entail contradictions if false or different. But why not take the easy out that Hume utilized and just define the universe as necessary and thus we get rid of the contingency of the universe in the first place? Maybe an immaterial spaceless timeless supernatural mind that causes the universe could use a separate argument to be proven necessary instead of merely asserting him or defining him with such property?

Sincerely yours,



Dr. William Lane Craig’s Response

Dr. William Lane Craig

Thank you, Mohammad! We hope the new site will draw many more visitors, since nearly half of all people are using mobile devices to surf the web.

For those who are unfamiliar with Leibniz’s argument, let’s review its premisses:

1. Everything that exists has an explanation of its existence (either in the necessity of its own nature or in an external cause).

2. If the universe has an explanation of its existence, that explanation is God.

3. The universe exists.

4. Therefore, the explanation of the existence of the universe is God.

Although this is not the point of your question, you have some confusion concerning strict logical necessity/possibility and broadly logical necessity/possibility that is worth clearing up. To be strictly logically impossible a sentence has to be a self-contradiction or to imply a self-contradiction by the logical rules of inference. For example, “Some married women are not married women” is strictly logically impossible. But “Some wives are not married women” is not strictlylogically impossible. But it is broadly logically impossible: there is no possible world in which unmarried wives exist. So some sentences are broadly logically necessary even though they are not strictly logically necessary, like “The Prime Minister is not a prime number,” “Everything that has a shape has a size,” and “Every red object is colored.”

“God exists” is such a sentence. Its negation “God does not exist” is neither self-contradictory nor does it imply a contradiction, but given that God is a metaphysically necessary being, it is broadly logically impossible that God does not exist. As Leibniz would put it, He exists by a necessity of His own nature.

So your quite proper question is, why think that “The universe exists” is not similarly broadly logically necessary? Its negation “The universe does not exist” is neither self-contradictory nor does it imply a contradiction, but nonetheless one could say that the universe exists by a necessity of its own nature. In that case the universe is the metaphysically necessary being sought by Leibniz.

I’d encourage you to read and reflect on what I’ve already written about this question (Reasonable Faith, 3rd ed., pp. 108-10; On Guard, pp. 60-3). In a nutshell I argue that because a different collection of fundamental particles could have existed instead of the ones that do exist, a different universe could have existed instead of this one. The atheist who tries to avoid Leibniz’s conclusion by holding that the universe is metaphysically necessary is thus thrust into the position that every sub-atomic particle that exists is metaphysically necessary, which seems highly implausible, to say the least.

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