 The aim of the metaphysical project is to uncover the metaphysical grounds or truth-makers for causal claims. The main division in the metaphysics of causation is between broadly Humean and non-Humean accounts of causation. Humean accounts deny the existence of fundamental modalities and maintain that fundamentally the universe is composed of a distribution of categorical properties and relations instantiated by localized entities—what David Lewis called the “Humean mosaic” (Lewis 1973; Loewer 2012). On the Humean view, all true modal claims, including causal claims, are grounded in non-modal features of the mosaic. Even though Humeans deny that modal properties, including causal properties, are part of the world’s fundamental ontology, they may allow for the existence of non-fundamental causal facts that are reducible to fundamental physical properties. Thus, Humeans can be—and many of them are—non-fundamentalists rather than eliminativists about  causation.[1]