William Lane Craig’s moral argument for God’s existence is as follows.
(1) If God does not exist, then objective moral values and duties do not exist.
(2) But objective moral values and duties do exist.
(3) Therefore, God exists.
In defense of (2), Craig offers an appeal to intuition. Here’s an excerpt from one of his debate opening statements:
But the fact is that objective moral values do exist, and we all know it. There’s no more reason to deny the objective existence of moral values than to deny the objective reality of the physical world. Actions like rape, torture, and child abuse aren’t just socially unacceptable behavior. They’re moral abominations. Even Ruse himself admits, “The man who says that it is morally acceptable to rape little children is just as mistaken as the man who says two plus two equals five.” Some things are really wrong. Similarly, love, equality, and self-sacrifice are really good.
How, precisely, does this support (2)?
One interpretation of Craig’s sparse remarks is that “we all know” objective moral values exist by intuition. In a forthcoming paper, “Intuition Mongering,” Moti Mizrahi argues that appeals to intuition are similar to appeals to authority. If that’s the case, then that creates a problem for appealing to intuition to support (2).
Here’s why. Start with the logical form of a particular type of inductive argument called the statistical syllogism.
(4) Z percent of F are G.
(5) x is F.
(6) Things that are F bear such-and-such relevance to property G. [This premise is usually suppressed.]
(7) Therefore, x is G.
The argument from authority is an inductively correct argument which conforms to the same pattern as the statistical syllogism.
(8) The vast majority of statements made by authority A concerning subject S are true.
(9) p is a statement made by A concerning subject S.
(10) Therefore, p is true.
As Wesley Salmon points out, an inductively correct argument from authority must satisfy two conditions.
(a) Subject S must be within authority A’s area of expertise.
(b) There must be no equally qualified authorities who disagree with A about S.
If an argument from authority does not satisfy both (a) and (b), it is inductively incorrect: it fails to make the conclusion probable.
Now consider the argument from intuition.
(11) The vast majority of intuitions held by philosopher A concerning subject S are true.
(12) Concerning subject S, it seems to philosopher A that p.
(13) Therefore, p is true.
Conditions (a) and (b) also apply to the argument from intuition.
What does all of this have to do with Craig’s moral argument? If Craig’s defense of (2) is interpreted as an appeal to intuition, it fails to satisfy condition (b). There are equally well qualified philosophers who disagree with Craig about the objectivity of morality. Indeed, non-cognitivists deny that morality is even cognitive! The upshot is that an argument from intuition for objective moral values is weak.