  Suppose that this robust form of property dualism is true. Can mental substances or events cause what they do qua mental, in virtue of their mental properties? The arguments against soul–body interaction, now couched in terms of properties, could enter again here. For example, if you were worried about the mind–body nexus for souls (§2.1), it seems you should also wonder how non-physical properties can find any traction in the physical world. Similarly, Completeness (§2.4) seems to lose none of its attractiveness when formulated explicitly in terms of properties. You could add to the principle a clause stipulating that a “sufficient physical cause” is one that’s sufficient in virtue of its physical properties (see also §5.4). Bring in No Overdetermination, and the efficacy of mental properties is again threatened. The arguments here and the responses to it are structurally similar to those in §2, so we will not pursue further this version of the property-based problem.  (Property dualism also faces the Exclusion Problem, to be discussed in §6.)