Proceedings of the Annual Meeting of the Cognitive Science Society

Causal scope, the number of different effects a cause can pro-duce, is a salient feature of causes. In the present research, weaddress the question whether reasoners use causal scope as adiagnostic cue to infer the strengths of individual causal links.In three experiments, we manipulated the number of effects ofa cause, and asked subjects to assess the causal strengths ofsingle causal links. The results document a clear influence ofcausal scope on perceived link strength. In particular, subjectstended to display a “dilution” effect. They perceived a causallink to be weaker if that link belonged to a cause that is capa-ble of producing additional effects. This dilution effect can beexplained by a dispositional notion of causality according towhich a cause possesses a certain amount of causal power orcapacity that it distributes across its different causal pathways.