Abstract

This paper is an investigation into the notion of degree of influence, and its application to the problem of pre-emption. In 'Causation as Influence', Lewis presented a new account of causation under determinism and some new observations on the problem of pre-emption. He claimed that, in cases of pre-emption, the pre-empting cause is much more of a cause than its pre-empted alternative; it has much more influence. I begin by trying to make sense of the notion of degree of influence. Then I emend Lewis's approach to pre-emption in response to objections, compare it to Kvart's Sustainably Reducible Influence account, and finally conclude that all these accounts fail to solve the problem of pre-emption.