  This is a hotly contested question, and I will here simply sketch a case that selective explanations of adaptations are robustly teleological. The interested reader may want to refer to the literature on this question referred to in the discussion and listed in the list of readings provided at the end of this entry. A question I think not worth discussing is whether the word ‘teleology’ should be replaced by ‘teleonomy’. Etymologically, they come to the same thing; and the philosophical arguments given in favor of the change all rest on an historically doubtful assumption—that philosophical defenses of teleology have always been either theistic or vitalistic. The serious philosophical issue can be put simply and directly: in selection explanations of adaptations, are the functions served by adaptations a central and irreducible feature of the explanans in such explanations?  If the answer is yes, the explanations are  teleological.[14]