We've been commenting on Dogma Debate episode #121, where I was a guest. In the subsequent episode, a caller offered three critiques of an argument I gave. The hosts liked them, so if they're blunders, they're blunders that 15,000+ atheist listeners are now equipped with.
To clarify, it was Alexander Pruss (Baylor professor of philosophy) who published the simplified Leibnizian Cosmological Argument that I quoted on the show. It comes from The Blackwell Companion to Natural Theology (2009). I'll explain the vocabulary of the argument, but first read it over:
Step 1. Every contingent fact has an explanation.
Step 2. Some contingent fact includes all other contingent facts. [A.k.a. the "Big Conjunctive Contingent Fact"]
Step 3. Therefore, there is an explanation of this fact.
Step 4. This explanation must involve a necessary being.
The “Gap problem” is the problem of how one gets from that last step to “This necessary being is God,” but let's make sure we understand what “contingent” and “necessary” mean first, so we have the resources to understand the caller's objection and the answer to it.
The concepts of possibility and necessity are academically respectable, being used as “operators” in widely-accepted modal logic (for those who want to investigate). Insofar as the proposition <2+2=4> cannot fail to be true, we say it is true “by necessity,” or <Necessarily, 2+2=4>. Here is another example: <Necessarily, square-circles do not exist>. A “contingent” truth, by contrast, is a truth that is not by necessity true. I offered two examples on Dogma Debate to illustrate: <David Smalley is bald>, and <The Earth revolves around the sun>.
Commenting on the first premise, that “every contingent fact has an explanation,” the caller stated “I really agree with his first one.” This is wise—the first premise is just a restatement of the resricted “principle of sufficient reason,” and individuals who deny it run into some really hairy problems! However, the caller continued on to target premises 2 and 3:
“[Blake] said that there is a conjunctive contingent fact that contains all contingent facts, and that conjuctive contigent fact has to have a necessary explanation. But that's not true necessarily. For example, evolution contains facts like natural selection, adaptation, but it is also explained by these facts. So this conjunctive contingent fact can actually be explained by all these contingent facts.”
What I want to say is this:
Thanks for your cordial feedback (I mean that). Here are my thoughts.
First, insofar as you granted premise 1, and insofar as premise 3 falls deductively out of the conjunction of premises 1 and 2, you are required to deny premise 2. But premise 2 sure seems plausible, doesn't it? Maybe it was just for lack of time, but you certainly gave no _direct _objection it. In fact, you seemed to presuppose it was plausible by trying to conjoin all the propositions relevant to evolutionary theory.
Second, if we could properly speak of the theory of evolution in the way you did (which I'm not sure we can), the contingent facts of which the theory would need to be comprised are facts like “mutation x occurred at time y,” and “x was born at time y and location z,” and “x had y number of offspring.” If you amass those together, however, that conjunctive fact will have an explanation, presumably in the form of a series of facts about natural laws, chemistry, geology, the _origin _of life at its specific time and location, conditions of the planet through evolutionary history, and more.
Now sure, there are sums of contingent facts which are not directly explained by a necessary fact. But so what? Premise 3 only says that a necessary fact is required to explain the so-called “Big conjunctive contingent fact” (BCCF)—the book of _all _contingent facts. This fact is not just a sum of contingent facts—it's the sum of _all the contingent facts. The reason the BCCF in particular_ would need a necessary fact to explain it is because, by virtue of premise 1, it has an explanation, and the explanation cannot itself be contingent because the contingent facts are all contained within BCCF already. (I assume here that you grant the almost universally accepted principle that something cannot explain itself, any more than it can cause itself: explanation is an "irreflexive relation" [Wiki]).
Consequently, citing evolutionary theory as a conjunctive contingent fact and saying it has no explanation is one way to not object to the Leibnizian Cosmological Argument.
The call didn't stop there, of course. The so-called “Gap Problem” (defined above) is a common way to challenge the Leibnizian Cosmological Argument as a proof for theism, but the caller nuanced his particular Gap Problem with the amazing claim that ”it simply could be an equation,” which I think is easy to refute. For a last objection, the caller then made what I believe is the biggest mistake of the three:
“Besides that, God is not necessary because we can see the Universe acting without God and God doesn't have to be there...”
Question: These are the two objections I will discuss tomorrow. Until then, what do you think about the caller's objection? What do you think of my response?