An Essay on Material Necessity

Abstract

At the one extreme stands Hume, who -at least according to common conceptions - rules out entirely the possibility of material or non-logical necessity, and who therefore rules out also the possibility that we might enjoy that sort of certain knowledge that earlier philosophers had assumed as a matter of course to be correlated therewith. At the other extreme stands Adolf Reinach, the hero of our present story, who defends the existence of a wide class of material necessities falling within the domain of what can be a priori known. More precisely, Reinach holds that there are certain categories of entity whose factual instantiation brings with it as a matter of necessity the instantiation of certain other correlated categories. The instantiation of the category color necessitates in this fashion the instantiation of the category visual extension.