Frank Kogan

So I'd say you'd be better off thinking of (at least) two different incredulities.

First, a disbelief in absolute transcendence, in the idea that there's a realm (facts or logic or whatever) that, while being absolutely independent of discourse, can nonetheless be a basis from which to ground and judge all discourses.

Second, a skepticism towards a "system's" claim to speak for all of human psychology or to give "laws" that explain all cultural development, and a skepticism towards claims that the systems that do work - such as physics, evolutionary biology - are successfully being extended to speak for all of human psychology and all cultural development.

Notice a big difference between the first and the second, not just in what one is being incredulous towards, but also in the force of the incredulity. The first is a disbelief; it's analogous to atheism. It says that something doesn't exist, that something is unintelligible. The second merely says that something doesn't seem too likely at the moment. I suppose one could extend the second by saying that no features of psychology can be common to members of all cultures and that no cultural developments can be common to all societies, but that's simply blind dogmatism, not any kind of principle.

(I know that you're saying that the word "relativism" tends to arise in relation to morals; but the basic arguments are the same. That is, (a) disbelieving in a neutral ground that's not dependent on the rest of your ethical system but that can nonetheless provide the first principles of your system is not the same as (b) deciding that your ethical system cannot or should not be generally applied across cultures.)