 Some theorists have argued for the pluralistic idea that biology may incorporate (at least) two notions of function, one to explain the presence of traits and the other to explain how those traits contribute to the complex capacities of organisms (Millikan 1989; Sober 1993; Godfrey-Smith 1994). Ron Amundson and George Lauder (Amundson &amp; Lauder 1994) argue that paleontology is a part of biology which cannot make use of the etiological account because the selection regime for extinct organisms is generally inaccessible, and it must therefore depend on Cummins-style functional analysis of fossilized remains. However, defenders of pluralism may respond that even if it is correct to say that not all parts of biology can use both notions of function, this is consistent with both accounts having a role within biology. 