 We have surveyed two salient arguments for the causal inefficacy of dispositions. Note that they, to be successful, would have to be accompanied by an account of what causal efficacy is, and the large literature on causal efficacy attests to the difficulty of complying with this demand. McKitrick (2005) surveys several of the existing accounts of causal efficacy—or, in her terms, causal relevance—and argues that the most plausible of these give us no clear reason for thinking that dispositions are causally irrelevant to their manifestations.