 Another version of this argument says that fundamental moral philosophical principles are, if true at all, necessarily true, and that empirical research can establish at best only contingent  truths.[18]  But if fundamental moral theories are necessary, then they are necessary for creatures like us. And one thing that empirical investigation can do is to help establish what sorts of creatures we are. Imagination needs material to work with. When one sits in one’s armchair, imagining a hypothetical scenario, one makes a whole host of assumptions about what people are like, how psychological processes work, and so on. These assumptions can be empirically well or poorly informed. It’s hard to see why anyone could doubt that being well informed is to be preferred. Likewise it’s hard to see how anyone could doubt the relevance of experimental evidence to better grounding our empirical assumptions, in this case our assumptions relevant to moral philosophy. Exactly how experimental—or more broadly, empirical—evidence is relevant, and how relevant it is, are at present hotly contested matters.