Abstract
The validity and utility of the proximate-ultimate distinction in biology have recently been under debate. Opponents of the distinction argue that it rules out individual-level organismic processes from evolutionary explanations, thereby leading to an unfounded separation between organismic causation and evolutionary causation. Proponents of the proximate-ultimate distinction, on the other hand, argue that it serves an important epistemological role in forming different kinds of explanation-seeking questions in biology. In this paper we offer an interpretation the proximate-ultimate distinction not only as a means of forming explanation-seeking questions, but also as a distinction that can help highlight the way in which individual-level organismic processes can be evolutionary causes. We do this by interpreting the distinction between proximate and ultimate causes as a distinction between structuring and triggering causes.