 Millikan (1984) proposes a different approach to functional kinds, arguing that they arise from the successive copying or reproduction of new objects from older ones. A population of objects copied in the right way, and copied because they perform a function, form a “reproductively established family”. Millikan (1999, 2005) applies this account to linguistic and social kinds as well as biological ones. Millikan also analyzes social convention in terms of reproductively established families, and other theorists have recently applied her theory to artifacts (see  section 5.5).