  Why are we good? Why are we bad? Questions regarding the evolution of
morality have spurred an astoundingly large interdisciplinary literature. Some
significant subset of this body of work addresses questions regarding our moral
psychology: how did humans evolve the psychological properties which underpin
our systems of ethics and morality? Here I do three things. First, I discuss
some methodological issues, and defend particularly effective methods for
addressing many research questions in this area. Second, I give an in-depth
example, describing how an explanation can be given for the evolution of
guilt---one of the core moral emotions---using the methods advocated here.
Last, I lay out which sorts of strategic scenarios generally are the ones that
our moral psychology evolved to `solve', and thus which models are the most
useful in further exploring this evolution.
