  On some versions of the inheritance solution, what the higher-level mental property derives from its physical realizer is some weaker or “lower-grade” form of causal relevance. For example, Jackson and Pettit (1988, 1990) distinguish the robust “causal efficacy” of physical properties from the weaker “causal relevance” of higher-level properties. Causal relevance in this sense is an explanatory notion: as one might put it, behavior is produced at the physical level, but by being realized in the physical, mental properties inherit an explanatory relevance they wouldn’t have otherwise. An advantage of such a view is that it accords a derived form of relevance to mental properties, but in a way that respects both the priority of physical causation embodied in Completeness as well as the principle of No Overdetermination. (For similar views, see Kim 1984; Levine 2001, §1.5; Segal 2009. Those who appeal to the counterfactual dependence of behavior on the mental [§5.3] might also fall into this category. For an answer to the charge that counterfactual dependence is “causation lite”, see Loewer 2007; Menzies 2007.)