Humean metaphysics is characterised by a rejection of necessary connections between distinct existences. Dispositionalists claim that there are basic causal powers. The existence of such properties is widely held to be incompatible with the Humean rejection of necessary connections. In this paper I present a novel theory of causal powers that vindicates the dispositionalist claim that causal powers are basic, without embracing brute necessary connections. The key assumptions of the theory are that there are natural types of causal processes, and that manifestations of powers are identified with certain kinds of causal processes. From these assumptions, the modal features of powers are explained in terms of internal relations between powers themselves and the process-types in which powers are manifested.
Basic causal powersA number of philosophers claim there are properties which might be characterised as basic causal powers. In particular, those philosophers identifying themselves as "dispositional essentialists", or simply "dispositionalists" appear to be committed to this idea. 1 Causal powers have distinctive modal features. Frequently, such features are explicated by appeal to a necessary connection, perhaps between the instantiation of a power and the truth of a conditional sentence. If P is a power to yield response R to stimulus S, then whenever something x instantiates P, a conditional roughly of the form 'If it were that Sx, then it would be that Rx' will be true. Giving a precise account of the required conditional has proven difficult, but there is reasonably widespread agreement that the instantiation of a power necessitates the truth of a non-trivial modal proposition -typically a non-material conditional. 2 1.