'Tis our reason which presents a false notion or species to our moral faculty....We sometimes chuse and like, in point of interest, what is in event detrimental to ourselves. No man thence concludes that we are not uniform in self-love or liking of our own interest. Nor do like mistakes about the moral qualities of actions prove either that we have no moral sense, or that it is not uniformly constituted.
Francis Hutcheson, System of Moral Philosophy I.5.v. Hutcheson's own preferred explanation for moral differences is threefold: (1) Ignorance about what actually tends to public happiness as a consequence; (2) Narrow focus on a particular subgroup of humanity rather than taking an enlarged and truly human view; and (3) Differences of opinion about the objects of divine commands.