Abstract

This paper puts the concept of necessary physical dispositions to the test, using the analytic tools of possible world semantics and the Scotistic concept of synchronic contingency. It shows that any concept of physical disposition, which implies that an effect obtains in all possible worlds where the initiating circumstances obtain, is untenable, given the exigencies of the natural sciences. Apparent solutions to this problem, either by using the concept of relative necessity or the model of necessary core-laws of reality, are proved to be illusory. Following the refutation of such a necessary concept of natural disposition, and elaborating on the work of Kyburg (among others), an alternative concept of physical disposition is developed. It is characterized by the fact that a disposition's effect, though obtaining in many possible worlds, does not obtain in all worlds where the initiating circumstances obtain. This metaphysically 'open' concept of disposition fits well with the demands of the empirical sciences. Some corollaries are hinted at, e.g. that it is less reasonable now to adhere to a worldview that does not allow for miracles than to adhere to one that does