Abstract
Shoemaker presented a theory of properties according to which there are no metaphysically possible worlds that are not causally possible, because the causal powers of properties are essential to them. The theory apparently has the consequence that the range of metaphysically possible worlds is considerably narrower than has normally been thought. On closer inspection, however, it seems to leave open the possibility that there are possible worlds with "alien" properties that are not instantiated in the actual world, those properties being governed by laws that do not govern actual world properties. This paper examines whether this possibility is a serious threat to Shoemaker's theory, and concludes that it may indeed be.
