Abstract

This paper characterizes the role of the experimenter in causal explanations of laboratory phenomena. Causal explanation rests on appeals to the experimenter's efficacy as a causal agent. I contrast "demographic" and "genetic" explanations of stochastic outcomes in a set of competition experiments in ecology. The demographic view ascribes causes to the experimenter's agency in setting up the experiment and to events within the experimental set-up. The genetic view ascribes causes to an unrecognized effect of the experimenter's sampling process prior to the experimental set-up.