Baggett and Walls on 'The' Moral Argument vs. 'The' Argument from Evil

David Baggett	Jerry Walls

The idea that there is some sort of connection between moral arguments for theism, on the one hand and arguments from evil against theism, on the other hand, is not new. In this blog post, I want to comment on a very cryptic statement made by Baggett and Walls about this connection. In their book God and Cosmos, they write:

... Second, it should be said in such a case that the probability of theism has increased (by much or a little) relative to morality; in theory the probability of atheism could increase or decrease relative to other phenomena. (However, the success of the moral argument would decisively undercut the problem of evil, which tends to be counted as the best evidence against theism.) (20, boldface mine)

This is a strong claim by itself, but it is even stronger in light of how modest their abductive moral argument is. In my last post, I steelmanned their moral argument as follows:

1. Hypothesis T of the set {T, A1, ..., An} is the best explanation of the evidence E in being superior to its rivals {A1, ..., An} in satisfying the five criteria for explanation candidates.
2. The explanation candidates {T, A1, ..., An} are a jointly exhaustive set.
3. Therefore, other evidence held equal, T is more probable than naturalism.

Now, contrast that argument with Paul Draper's evidential argument from pain and pleasure, widely considered to be one of the strongest, if not the strongest, versions of the evidential argument from evil.

1. O [a statement consisting of known facts about biological pain and pleasure] is known to be true.
2. Theism (T) is not much more probable intrinsically than the hypothesis of indifference (HI) [i.e., Pr(|T|) is not much greater than Pr(|HI|)].
3. O is much more likely on the assumption that the hypothesis of indifference is true than it is on the assumption that theism is true [i.e., Pr(O | HI) >! Pr(O | T)].
4. So, other evidence held equal, theism is probably false.

Suppose we grant, merely for the sake of argument, that the steelman version of Baggett's and Wall's abductive moral argument is successful. How, precisely, does the conclusion of that argument "decisively undercut" the conclusion of Draper's argument? At least in the introduction of their book (which is where the quotation above came from), Baggett and Walls do not say. Nor is it obvious to me. It seems to me that an additional argument is needed to justify the claim that, necessarily, a successful moral argument "would decisively undercut" evidential arguments from evil. Perhaps they give such an argument in chapter 3, which discusses the problem of evil.