Unfortunately it’s not as easy as all that. Moral relativism is not, after all, self-refuting.
The claim “there are no absolutes” is self-refuting because it is the equivalent of “this sentence is incorrect.” In order for each to be correct, they must be incorrect. This is a fallacy.
The claim “there are no
moral absolutes,” however, is the equivalent of “the sentence before this one is incorrect.” It’s perfectly valid. You see, the claim that there are no
moral absolutes is not a claim about absolutes in general. Most moral relativists readily affirm at least some absolute truth (throwing in their lot with science and mathematics and such).
Once again, it is regretable that debunking moral relativism is not as easy as self-refutation. The strongest argument against moral relativism is, in my opinion, its own inconsistencey. For instance, a moral relativist cannot say that you or I
ought do anything, because that implies a moral obligation. Therefore they cannot even say that we
ought subscribe to their philosophy (of relativism). There’s a list of contradictions.
I’ll second infoguy’s recommendation on the Beckwith/Koukl book, which I do own. It’s wonderfully concise. Also, get on
www.veritas.org, and find Greg Koukl’s talk on moral relativism. It’s about an hour long, and is very useful. Good luck and God bless.