As will be discussed further below, much of the twentieth century was marked by debates among biologists about the relative importance of drift and selection in evolution. Were those debates at least in part the result of conceptual unclarity? Millstein (2002) argues that we need not accept this inadvertent consequence of Beatty’s argument, and that selection can, in fact, be distinguished from drift. In order to do this, three extensions should be made to Beatty’s account. First, similar to Hod