As Hume had reduced reason to nature, Kant hoped to save reason by divorcing it from nature more thoroughly than anyone had yet dared. He purified reason of its traditional character as pupil, receiving what nature chose to give, and transformed it into a judge, “who compels the witnesses to reply to those questions which he himself thinks fit to propose.”1 Thus Kant put the defence of creative reason on a totally new footing, which was, he hoped, not so vulnerable as Hume had shown the old one to be.
If one accepted Hume’s picture of human nature, the whole hierarchy of being was rearranged. The Treatise proposed a metaphysics that was profoundly subversive of the Christian outlook. It was no wonder that Hume’s friends wished him to withhold from publication his Dialogue on Natural Religion, and that he should have taken such great pains to insure its appearance after his death. For the Dialogue stated the postulate upon which the Treatise was based in its most general and simple form.
The general question of how mind and matter were related had interested Hume from the beginning. He had studied Bayle’s account of Strato’s atheism and Cicero’s Dialogue of the Nature of the Gods, and was curious about the Cartesian philosophy of the brain. He had noticed throughout the history of philosophy that the most prevalent views had driven a sharp line between matter and spirit. Either they took up an atomistic, materialist position, like that of Epicurus, Democritus, Leucippus, and asserted that there was nothing but senseless matter and chance, or else they insisted that nature could not be explained without adding a spiritual, ordering force beyond matter. There was, however, a third possibility, suggested by Strato, and discussed by Cicero, that order is somehow inherent in matter. Strato’s atheism was “the most dangerous of the ancient, holding the origin of the world from nature or a matter endowed with activity,” Hume remarked in his notes.2 What he himself had decided, he made plain in the Dialogues Concerning Natural Religion.
Thought is not the only principle of order disclosed in experience, he pointed out. There are an infinite number of springs and principles which even our limited knowledge of nature shows her to possess—heat and cold, attraction and repulsion, instinct and generation. We know that every part of nature has its own life and motion, which not only operates it, but coordinates it with the whole. Our experience would seem to deny the possibility of matter utterly devoid of order, or, even spirit without matter. Certainly in all instances that we know, thought can influence matter only when it is joined to it, and it can be as easily influenced by matter. We have no reason to make “this little agitation of the brain” the model of the universe.3
Besides, as we constantly see reason arise from generation, never generation from reason, we might more easily make generation the principle of order than reason. It is no less intelligible or compatible with experience to say that the world arose by vegetation from a seed, than to say that it arose from a divine reason or contrivance.1 An orderly system might as easily have been spun from the belly of an infinite spider as from a mind. Reason itself is no more intelligible than any other ordering principle: “But reason, in its internal fabric and structure, is really as little known to us as instinct or vegetation; and perhaps even that vague, undeterminate word, nature, to which the vulgar refer everything is not at bottom more inexplicable.”2
In the Dialogue, no one of the disputants gains a victory, although no one really refutes Philo’s statement:
For aught we can know a priori, matter may contain the source or spring of order originally within itself, as well as mind does; and there is no more difficulty in conceiving, that the several elements from an internal unknown cause, may fall into the most exquisite arrangement, than to conceive that their ideas, in the great universal mind, from a like internal unknown cause, fall into that arrangement. The equal possibility of both these suppositions is allowed.3
The emphasis falls not so much on any particular theory, as on denying the possibility of knowing what either matter or mind is, or precisely how the universe is arranged: “These words, generation, reason, mark only certain powers and energies in nature, whose effects are known but whose essence is incomprehensible; and one of these principles, more than the other, has no privilege for being made a standard to the whole of nature.”4 The sum of Hume’s argument is that by experience we know that there is an order in nature, but we cannot know how it comes to be. It is therefore presumptuous to try to distinguish matter from mind, to say that one lacks order and the other imposes it. The very distinction is beyond our capacities. Even Father Malebranche, he pointed out, considered it blasphemous to call God a spirit, and argued that He was neither spirit nor matter, but simply, “ ‘He that is,’ or, in other words, Being without restriction, all Being, the Being infinite and universal.”1 It was far better to rest with a more modest theory, and ascribe “an eternal inherent principle or order to the world, though attended with great and continual revolutions and alterations.” This, by being so general, solved all difficulties; it was perhaps “not entirely complete and satisfactory,” but it was at least a “theory that we must sooner or later, have recourse to, whatever system we embrace.”2 For we know only that “everything is surely governed by steady inviolable laws.” If we could know the “inmost essence of things,” we would then “discover a scene, of which, at present we can have no idea.”3
Hume preferred to leave the various arguments in his dialogue more or less in balance, not merely because he might thereby avoid offending popular opinion, but because, above all, he wanted to say that in the end we can but acknowledge a mystery. Neither spirit nor matter was to be made supreme. He had indeed attacked the argument from design, that argument for God’s existence which the faithful regarded as the very heart of religion. And yet he was not an atheist strictly speaking, but a true defender of religion in its most generic meaning, as a sense of wonder. For he insisted that understanding the order of the universe was not within man’s power:
The whole is a riddle, an aenigma, an inexplicable mystery. Doubt, uncertainty, suspence of judgement appear the only result of our most accurate scrutiny, concerning this subject. But such is the frailty of human reason, and such the irresistible contagion of opinion, that even this deliberate doubt could scarcely be upheld; did we not enlarge our view, and opposing one species of superstition to another, set them a quarrelling; while we ourselves, during their fury and contention, happily make our escape into the calm, though obscure regions of philosophy.1
Hume had used the “experimental method” not to confirm but to thwart the scientific spirit. For the scientist, however much he may assert that he wishes merely to observe the phenomena of this world, however much he denies the possibility of explaining them, is driven by the momentum of his own work into attempting to discover all or believing he could. He may say that his general laws describe nothing real, but even if he himself refrains from doing so, his disciples, as Newton’s did, will take the reality of his scientific laws for granted. But Hume not only insisted on a fundamental, impenetrable mystery; he not only disintegrated the very power that was supposed to give men access to certain and undeniable truth. He denied also the sort of world that the scientists, from Copernicus on, had been creating.
Although insofar as he expelled formal and final causes Hume spoke for the new experimental science, in another way he was behind his time. On the one hand, he admired Newton for the wrong reasons: “While Newton seemed to draw off the veil from some of the mysteries of nature, he showed at the same time the imperfections of the mechanical philosophy; and thereby restored her ultimate secrets to that obscurity in which they ever did and ever will remain.”2 On the other hand, despite his criticism of “the mechanical philosophy,” Hume had taken his stand with Newton’s opponents who refused to accept a mathematical force. He used Newton’s own method to declare himself against the timeless world of immaterial forces that Newton, in completing the world view of the new science, proposed to substitute for a simpler, mechanical world, where men did not venture beyond everyday experience. The effect of Newtonism was to abolish the world of more or less, of qualities and sense perception, of concentration on our daily life, and to replace it by an Archimedean universe of precision, of quantity, and rest, where there is a place for everything but humanity. It substituted a mathematical nature for a physical nature, a world of being for a world of becoming and change. It reduced