jats:pReductionists say things like all mental properties are physical properties; all normative properties are natural properties. I argue that the only way to resist reductionism is to deny that causation is difference making (thus making the epistemology of causation a mystery) or to deny that properties are individuated by their causal powers (thus making properties a mystery); that is to say, unless one is happy to deny supervenience or to trivialize the debate over reductionism. To show this, I argue that if properties are individuated by their causal powers, then, surprisingly, properties are individuated by necessary coexemplification.</jats:p>