Published online by Cambridge University Press: 28 February 2022
Hume contributed two ideas to our understanding of causality. First, he held that when one event causes another, the physical ontology of this situation contains two items, not three. There is the causing event and its resulting effect; but there is not, in addition, a third physical entity consisting of their causal relation. Causality, Hume believed, is a relation like that of one individual's being taller than another. Sam and Aaron are terms of this relation. Platonists may think that there is a third term here — an abstract object known as the Tal].er Ihan relation. But in the world of physical objects, Sam and Aaron are not joined by a third physical object that connects them in the Taller Than relation.
My thanks to Ellery Eells for useful comments.