Abstract

It is commonplace among friends of irreducible causal powers to depict powers as producing their characteristic manifestations as a matter of metaphysical necessity. That is to say that when a power finds itself in those circumstances that stimulate it, it cannot help but be exercised: its effects must occur. The result is a metaphysic that depicts the world not as loose and separate but as united by the strongest glue; this is but one way in which the world as understood by friends of powers differs from that of their Humean adversaries. However, this typical understanding of powers has recently come under attack. Schrenk and Mumford and Anjum have independently argued that metaphysical necessity is not up to the task of connecting a stimulated power with its manifestation. Employing the same devices friends of powers use in rejecting attempts to analyze power ascriptions in terms of counterfactual conditionals, Schrenk and Mumford and Anjum argue that any process a power elicits could be frustrated by way of interference or prevention, and thereby blocked. For example, striking a dry match against a rough surface will generally lead to its lighting, but as anyone who has attempted to do this can attest, a strong gust of wind can prevent the match from lighting, despite the striking having taken place. Hence, even in the presence of its stimulus, the power's manifestation is not ensured, and so the claim that powers necessarily bring about their manifestations is undermined.