But one would have to believe in the objective standards of sound reasons and effective inquiry – i.e. “logic” – to advance such an argument in the first place. But the only way one can believe in such a standard is to also be convinced of its value. Which is to say, logic as a cognitive standard can only be rationally judged to be of any value if one is rationally satisfied that one ought to reason in such a way. But any claim of “ought” is ultimately an ethical claim. Any claim that one “ought” to reason logically is a claim about the Right thing to do, the Good form of reasoning, the Valuable method of inquiry.
Lest there be any lingering doubt, the above argument does indeed place various ethical propositions at the very foundation of even the possibility of reasoned inquiry. Before there can be science, before there can be logic, before there can be any concern for truth at all, there must first be an accepted axiom that such things are good. So any attempt to quarantine relativism to “merely” an ethical claim is doomed to have that quarantine shattered by the rational necessity of an ethical commitment to the truth. Gary Herstein