The Argument from Disagreement (AD) (Mackie, 1977) depends upon empirical evidence for ‘fundamental’ moral disagreement (FMD) (Doris and Stich, 2005; Doris and Plakias, 2008). Research on the Southern ‘culture of honour’ (Nisbett and Cohen, 1996) has been presented as evidence for FMD between Northerners and Southerners within the US. We raise some doubts about the usefulness of such data in settling AD. We offer an alternative based on recent work in moral psychology that targets the potential universality of morally significant distinctions (e.g. means vs. side-effects, actions versus omissions). More specifically, we argue that a recent study showing that a rural Mayan population fails to perceive as morally significant the distinction between actions and omissions provides a plausible case of FMD between Mayans and Westerners.