KNOWLEDGE in reason for drawing conclusions from that experience? Experience gives us information only about past objects and occurrences: why should it be extended to future times and objects, which for aught we know resemble past objects only in appearance? Bread has nourished me in the past, but what reason does this give me for believing that it will so in the future? These two propositions are far from being the same, I have found that such an object has always been attended with such an eVect and I foresee, that other objects, which are in appearance, similar, will be attended with similar eVects I shall allow, if you please, that the one proposition may justly be inferred from the other: I know, in fact, that it always is inferred But if you insist that the inference is made by a chain of reasoning, I desire you to produce that reasoning (E II 34) No demonstrative argument is possible: there is nothing at all selfcontradictory in the supposition that the next time I put the kettle on the stove the water will refuse to boil But no argument from experience is possible; for if we countenance the possibility that the course of nature may change we cannot regard experience as a reliable guide Any argument from experience to prove that the future will resemble the past must manifestly be circular Clearly, therefore, it is not reasoning that makes us believe that it will At the level of argument, then, scepticism is victorious But Hume tells us not to be cast down by this discovery: we are led to believe in the regularity of nature by a principle stronger than reasoning This principle is custom or habit No one could infer causal relationship from a single experience, because causal powers are not something observable by the senses But after we have observed similar objects or events to be constantly conjoined, we immediately infer one kind of event from the other And yet, a hundred instances have given us no more reason to draw the conclusion than the single one did ‘After the constant conjunction of two objects— heat and Xame, for instance, weight and solidity—we are determined by custom alone to expect the one from the appearance of the other’ (E II 43) It is custom, not reason, that is the great guide of human life Kant’s Synthetic a priori Many readers have regarded Hume’s conclusion as small comfort in return for his devastating demolition of any reasoned ordering of our experience 156