(1) Explanation holds only when the explanans is conceptually related to the explanandum , and this can occur only at the same level of function.(2) A hypothesis of homology is the explanandum , the phenomenon that is to be explained; evolution provides the explanans, the explanation of the phenomenon.(3) In the short intervening period sociology has become obsessed with biology, and biology is asked to be the universal explanandum of humanity.(4) The more coarse-grained and abstract the explanandum , the more likely it is that general systemic factors, such as class structure or the dynamics of capitalism, will play an important explanatory role.(5) First, it is important to distinguish explananda of different types, and, in particular, to distinguish appetites from emotions.
