Full Idea
In evolutionary explanations you may explain a population trait in terms of what it is for the sake of an individual, or explain it in terms of what it was for the sake of in earlier generations, but never in terms of what the trait is for the sake of.
Gist of Idea
Evolutionary explanations look to the past or the group, not to the individual
Source
Rowland Stout (Action [2005], 2 'Functions')
Book Reference
Stout,Rowland: 'Action' [Acumen 2005], p.19
A Reaction
So my ears are for the sake of my ability to hear, but that does not explain why I have ears. Should we say there is 'impersonal teleology' here, but no 'personal teleology'? Interesting.