  A strength of autonomy solutions is that they secure a causal role for mental properties without running afoul of Completeness, as the physical realization of behavior is always matched with some physical properties of its cause. But do autonomy solutions respect No Overdetermination? Here matters are not as straightforward. Autonomy solutions present us with two properties, P and M, each sufficient for the behavioral effect. It might seem as if the dual explanandum strategy avoids this awkwardness, since P and M are relevant to different properties of the effect. But even here, overdetermination threatens, as the effect’s behavioral property is produced twice: directly by M, and indirectly by P, which produces the behavioral property’s physical realizer, which itself necessitates the behavioral property.