  A final mystery is epistemic. It may be maintained that it is quite unclear how we can know of moral facts. This mystery may stem from the idea that non-natural properties lack causal powers. So the mystery is how we could know of something that is causally impotent. Intuitionists might respond by asking why a property must be causally efficacious if we are to be able to know which things have that property. They may point out that, on some views, dispositional properties such as warmth, fragility, or colour properties, lack causal powers. These powers are located in the non-dispositional base properties on which the dispositional properties supervene, rather than in the dispositional properties themselves. If this view were true, that would not imply that we could not know whether something was warm, fragile, or coloured. And if that could be true of non-causal, dispositional properties, then it could be true of causally impotent moral properties.