At 12:11 PM, Giordano Sagredo said…
As a naturalist I can see no alternative to some kind of nonrealism, because ethical claims will ultimately depend on contingent anthropological and biological facts. I take it that our brains paint the world with a moral hue in a way analogous to the way it paints it with colors and humorous people.
Even if we found a moral module, akin to Chomsky's grammar module, such that we could predict, given a person's environment and genetics, what they will judge to be ethical (i.e., their judgments about what actions they are committed to, and the intention that all people be so committed), this would not imply that those judgments are "true".
I think the best we naturalists can do is agree that, given certain goals by which to measure behavior (e.g., some utilitarian or deontic rights-based metric), we can engage in valid and sound arguments about how to achieve those goals.
In practice, this doesn't seem a big problem, but in theory you can think of scenarios in which it is disastrous (e.g., a Nazi society that considers itself moral for having "exterminated" the Jews, and in which dissent has been eliminated). However, moral repugnance is not enough to establish moral realism, any more than seeing colored objects establishes that color is independent of the observer. I take claims about morality to be on a par with claims about someone being humorous. Can we say objectively that Chris Rock is humorous? I don't think so. However, we can still have rational discussions of what color an object is, or how funny someone is, and our judgments about such things will evolve over time based on such rational pressures.