It's all about the deep questions.
The Open Question Argument = Begging the Question
So, I was reading Alex Miller’s An Introduction to Contemporary Metaethics, and as soon as I read Moore’s famous Open Question Argument it struck me as an obvious example of begging the question. At best, it would qualify as an intuition pump (using Dennett’s phrase). I couldn’t imagine someone who was some sort of naturalist cognitivist realist about moral statements actually find this argument to have any persuasive power.
Here is an outine of the argument:
Consider any proposed naturalistic analysis N of a moral predicate M. The Open Question Argument maintains that it will always be possible for someone competent with moral discourse without conceptual confusion to grant that something is N but still wonder whether it is really M. Whether goodness is co-instantiated with any natural property or set of natural properties is in this sense always a conceptually open question. If, however, N really was an accurate analysis of M then the question, “I know it is N but is it M?” would not be open in this way for a conceptually competent judge any more than the question, “I know he is a bachelor but is he unmarried?” can be an open one.
From this it follows that there can be no adequate naturalistic account of good. For example, identifying “good” with “the maximization of happiness and the minimization of suffering” would not and could not be an adequate account of the word good. My problem with the argument is the premise that given any naturalistic analysis N of M, one can always ask “I know it is N but is it really M? I’m also fairly confident that any every person who disagreed with Moore would reject this premise. In fact, one could only hold that premise if one was already on board with Moore’s agenda. Hence, begging the question. The argument, I guess, would have some weight for people sitting on the fence about the issue, since their intuitions on the subject haven’t swung either way.