crete in that it is in fact raining out and contingent in the fact that it could be different outside like sunny, but it is not. In contrast to that a proposition based on intellect concerns relations between concepts that are always necessary like "all squares have four equal sides." But the truths of pure reason are necessary only because they exist in a self contained system with no mandatory reference to the external world. Only logical definition makes them true by making explicit what is implicit in their own terms, and these can claim no necessary relation to the nature of things. So, the only truths of which pure reason is capable are redundant. Truth cannot be asserted by reason alone for the ultimate nature of things. For Hume, metaphysics was just an exalted form of mythology, of no relevance to the real world. A more disturbing consequence of Hume's analysis was its undermining of empirical science itself. The mind's logical progress from many particulars to a universal certainty could never be absolutely legitimated. Just because event B has always been seen to follow event A in the past, that does not mean it will always do so in the future. Any acceptance of that "law" is only an ingrained psychological persuasion, not a logical certainty. The causal necessity that is apparent in phenomena is the necessity only of conviction subjectively, of human imagination controlled by its regular association of ideas. It has no objective basis. The regularity of events can be perceived, however, there necessity can not. The result is nothing more than a subjective feeling brought on by the experience of apparent regularity. Science is possible, but of the phenomenal only, determined by human psychology. With Hume, the festering empiricist stress on sense perception was brought to its ultimate extreme, in which only the volley and chaos of those perceptions exist, and any order imposed on those perceptions was arbitrary, human, and wi...
