Karl Popper

Karl Popper noted that, when social scientists are members of the society they study, they may affect that society. If the individuals to whom a theory initially applies come to understand that theory, then this understanding may affect their behaviour in such a way that the theory ceases to be applicable. This may be called the problem of reflexivity. In this paper, we identify such a problem in an apparently unlikely area: in the area of Condorcet’s famous jury theorem. Suppose that each individual member of some decisionmaking body has a greater than 0.5 chance of making a correct judgment, and suppose further that all individuals ’ judgments are independent from each other. Then the jury theorem states that the majority will make a correct judgment with a probability approaching 1 as the number of individuals increases. We argue that, if the individuals come to understand the jury theorem, then they may cease to make independent judgments, thereby undermining one of the conditions for the application of the theorem. Specifically, we suggest that the individuals may be faced with a temptation to free-ride on the epistemic efforts of others. We first develop the problem in some detail and then ask whether there are any escape routes that can protect the jury theorem against the effect of reflexivity. 1.