Full Idea
The causal powers are just a proper subset of the dispositional properties.
Clarification
A 'proper' subset is smaller than the set
Gist of Idea
Causal powers are a proper subset of the dispositional properties
Source
Brian Ellis (The Metaphysics of Scientific Realism [2009], 5)
Book Reference
Ellis,Brian: 'The Metaphysics of Scientific Realism' [Acument 2009], p.93
A Reaction
Sounds wrong. Causal powers have a physical reality, while a disposition sounds as if it can wholly described by a counterfactual claim. It seems better to say that things have dispositions because they have powers.