Stich's argument in his Nicod lecture 2 http://www.institutnicod.org/lectures2007_outline.htm : Whether moral disagreement is fundamental rather than dependent on lack of rationality, impartiality, or information by one or more parties to disagreement is an important philosophical issue. A body of research (Richard Brandt on Hopi acceptance of children playing with small animals in a way that causes them extreme pain and American aversion to such play; Richard Nisbett on different attitudes and physiological responses to honor-related scenarios in "honor cultures" such as the US South and non-honor cultures such as the US North; Doris et al on more honor-oriented and individual-sacrificing responses among Chinese than among American respondents; Henrich et al on different levels of sharing in economic games in different cultures) suggests that moral disagreements are in fact fundamental. In any case, whether that empirical evidence is persuasive or not, a plausible evolutionary theory of norm acquisition (Sripada and Stich) relies on the idea that people who grow up in environments in which different norms prevail will make different judgments even under ideal conditions; Saunders' criticism of Sripada and Stich for failing to acknowledge how their model of norm acquisition can support rationally-generated moral judgments is fair enough, but such rationally-generated moral judgments are themselves subject to fundamental disagreement, given different socially-acquired norms.
I find Stich's affirmative empirical case for fundamental moral disagreement in this lecture considerably less compelling than his critical empirical case for blurring the moral rule-conventional rule distinction in his first lecture. Apart from that secondary point, my main value competition reaction to his espousal of fundamental moral disagreement is to urge that the empirical and theoretical focus be broadened from cross-cultural fundamental disagreement to intra-cultural and intra-individual fundamental disagreement. If VC is right, we would expect the latter kinds of fundamental disagreement; in fact useful variation across individuals and groups within a culture, especially a complex one like that of the contemporary US, is likely to be considerably greater than variation across cultures. That is, the "Americans think it's disgusting to eat dogs and Koreans don't" kind of across-the-board cross-cultural variation, real as it is, likely pertains to matters less significant than topics like adultery as to which we should per VC expect even greater differences in attitudes (referring to actual attitudes, not necessarily to expressed ones) within cultures than across cultures, and should also expect fundamental moral disagreement (likely repressed) within a given individual.