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