L'efficacité causale des propriétés dispositionnelles macroscopiques

It is controversial whether a property can both be dispositional and causally efficacious. Mackie and Armstrong hold that dispositions can be causes, Prior, Pargetter and Jackson argue that they cannot. However, all parties of the debate agree on two ideas: 1) The dispositional properties at issue are macroscopic, and in principle reducible to a microscopic reduction base. 2) Only the microphysical base properties are causally efficacious. The disagreement is about whether the macroscopic disposition inherits this efficacy by being identical to its reduction base (Armstrong) or is epiphenomenal because not identical to its reduction base (Prior, Pargetter and Jackson). I challenge thesis 2, which seems plausible only if one conflates two senses of the word “basis” that can be clearly distinguished thanks to the predicate/property distinction. I show that the categorical basis of a disposition need not be its microscopic reduction basis. This allows me to defend the idea that macroscopic dispositional properties can be distinct from their microscopic base properties and nevertheless efficacious. Part of the importance of this topic lies in its bearing on the nature of mental properties: If I am correct about macroscopic dispositions in general, it becomes plausible to argue that mental properties of a subject are dispositional properties which are nevertheless causally efficacious for the subject's actions