Abstract

This paper introduces and defends a new principle for when a structural equation model is apt for analyzing actual causation. Any such analysis in terms of these models has two components: a recipe for reading claims of actual causation off an apt model, and an articulation of what makes a model apt. The primary focus in the literature has been on the first component. But the problem of structural isomorphs has made the second especially pressing (Hall Citation2007; Hitchcock Citation2007a). Those with realist sympathies have reason to resist the standard response to this problem, which introduces a normative parameter into the metaphysics (Hall Citation2007; Halpern and Hitchcock Citation2010, Citation2015; Halpern Citation2016a; Menzies Citation2017; Gallow Citation2021). However, the only alternative solution in the literature leaves central questions unanswered (Blanchard and Schaffer Citation2017). I propose an independently motivated aptness requirement, Evident Mediation, that provides the missing details and resolves the structural isomorph problem without need for a normative parameter.