Reasons, Coherence, and Group Rationality

If groups can have beliefs and other attitudes of their own, what determines which such attitudes the group rationally ought to have? A widespread presupposition is that group‐level beliefs should be a function of the beliefs of the group's members, and similarly for other attitudes. But a host of impossibility theorems show that no such aggregation function can satisfy intuitively attractive constraints while ensuring coherent group‐level attitudes. I argue that this presupposition is false. Group‐level attitudes should be a function of group‐level reasons (evidence, in the epistemic case), not individual‐level attitudes. This allows for a theory of group rationality that (i) bypasses a host of pessimistic results in the literature on judgment aggregation and (ii) treats rational individual‐level attitudes and rational group‐level attitudes in parallel.