The nature and units of social selection
On the basis of the technical definition of selection developed by George Price (1995), we describe two forms of selection that commonly occur at the social level, subset selection and generative selection. Both forms of selection are abstract and general, and therefore also incomplete; both leave aside the question of explaining the selection criterion and why entities possess stable traits. However, an important difference between the two kinds of selection is that generative selection can accommodate an explanation of how new variation is created, while subset selection cannot. An evolutionary process involving repeated cycles of generative selection can, in principle, continue indefinitely because imperfect replication generates new variation along the way, whereas subset selection reduces variation and eventually grinds to a halt. Even if the two kinds of selection are very different, they share a number of features. First, neither subset selection nor generative selection implies improvement: neither kind of selection necessarily leads to efficiency or implies systematic outcomes. Second, both subset selection and generative selection can lead to extremely rapid effects in a social population. Third, in the social domain, both generative selection and subset selection involve choice and preference in some way: neither form of selection necessarily excludes intentionality. In concluding the article, we single out a challenge for future research in identifying the role of various units of culture in selection processes and the multiple levels at which social selection processes take place.