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#248 Infinite Regress and the Leibnizian Cosmological Argument

January 16, 2012

Dr. Craig,

I cannot thank you enough for your apologetics work. I've been faithfully using your podcasts, debates, books and articles for about 4 years now. I've reworded a question I submitted earlier which was never selected. I'm hoping this version of the question will be more clear and easier to respond to.

I've been focusing my efforts recently on trying to get a deeper understanding of the Leibnitzian cosmological argument. This seems like an intriguing argument for the existence of God because it is persuasive to me and strictly a philosophical argument so regardless of what happens in science, I can know this argument will persevere. With that said, here's my concern:

I presented the Leibnitzian cosmological argument as follows to a friend:

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

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

Premise 3: The universe exists.

Conclusion: Therefore the explanation of the existence of the universe is God.

My friend then asked me, "Why not posit an infinite regress of explanations? What makes this any worse than positing God (acting as the uncaused causer) as the explanation that terminates the series of external causes?" Does the question, "What caused the universe?", lead to a draw between the atheist and the theist? Both believe everything that exists has an explanation -- the atheist posits an infinite regress of explanations and the theist posits that the explanations eventually terminate with God whose explanation is the necessity of His own nature. I think the atheist objection is a rejection to premise 2 as stated above. The atheist would likely restate premise 2 to say, "If the universe has an explanation of its existence, that explanation is God . . . or an infinite regress of explanations."

I found a brief mention of this issue in your Defenders II podcast in the Existence of God part 2 (about 17 minutes, 45 sec. into the podcast), when a student proposed that if things that existed through an external cause weren't ultimately explained by something that existed by its own nature, then nothing would exist. You responded, "This line of reasoning will involve you in arguing against the possibility of an infinite regress of explanations, so I prefer to do it this way so as to avoid those infinite regress type arguments." I'm hoping you can further clarify how the infinite regress of explanations objection has been avoided or addressed.

Can we simply consider the infinite regress of explanations as a set? Since the set taken as a whole has no explanation, this violates premise 1, right? Is it fair to say that if the atheist wants to posit an infinite regress of explanations, then they must be willing to deny premise 1 because they leave the set (which contains infinite members) unexplained?

I'm hoping you decide that many would find it edifying to hear a strong rebuttal to the view that the universe is explained by an infinite regress of explanations. Thanks.

Humbly submitted,


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Dr. craig’s response


My version of the Leibnizian cosmological argument, which you have accurately given above, Steve, is patterned on the formulation by the noted philosopher Stephen T. Davis. One of the features of Davis’ formulation that I found (and find) attractive is that it just avoids any need to argue about an infinite regress of explanations. It is so formulated that the question doesn’t even arise. That is what I was referring to in the Defenders podcast you reference.

Why is this? Simply because “the universe” is meant to be inclusive of all space-time reality. One doesn’t begin with the present event or state of affairs and seek its explanation and then in turn ask for an explanation of that event or state of affairs and so on, arguing that such a series can’t go on to infinity, lest nothing be explained. No, instead one just lumps everything together under “the universe” and asks, what is the explanation for the universe? So the universe will include any encompassing physical reality like a multiverse. Why does the multiverse exist? Is it by a necessity of its own nature or does it have an external cause?

Leibniz made a similar move in dealing with the possibility that the universe may be past-eternal, so that every state of affairs is explained by a temporally prior state of affairs ad infinitum. As Leibniz saw, such a hypothesis doesn’t answer the question why there is a universe at all. We can still ask, “Why does an eternal universe exist?” Recall that Leibniz’s cosmological argument isn’t seeking a temporally first cause; it’s consistent with the universe’s being past eternal. We may still ask of an eternal universe, “Why is there something rather than nothing?”

Similarly, there’s just no need to talk of an infinite regress of non-temporally ordered explanations (like an embedding multiverse). Just lump them all together as Leibniz did with the past states of the universe and ask, “Why does this hierarchy of entities exist rather than nothing?” There must, I think, be a metaphysically necessary being in order to explain why something exists rather than nothing.

So your friend is not denying premise (2) and offering some other explanation than God, not, at least, if he is using “the universe” as it is used in the argument, for the universe includes all that hierarchy of contingent things that might be imagined to exist. He’s really saying that there is no explanation for why this hierarchy of things exists. It has no external cause and is not necessary in its being. He thinks it just inexplicably exists. This is basically your response in your penultimate paragraph, except that we should eschew the language of sets and just talk about the universe as all of physical reality. The atheist says that in the absence of God there is no explanation why physical reality exists.

- William Lane Craig