In recent years there has been a growing interest among mainstream Anglophone moral philosophers in the empirical study of human morality, including its evolution and historical development. This chapter compares these developments with an earlier point of contact between moral philosophy and the moral sciences in the early decades of the Twentieth century, as manifested in some of the less frequently discussed arguments of G. E. Moore and W. D. Ross. It is argued that a critical appreciation of Moore and (...) Ross’s response to the emerging moral sciences of their day has significant implications for contemporary moral epistemology. The chapter also offers a novel interpretation of G. E. Moore’s ‘open question argument’. (shrink)