Life and Correspondence of David Hume, Volume 1

by John Hill Burton

The application of this system to the mathematics, and to natural philosophy, was so startling as to afford to some readers almost a reductio ad absurdum. The infinite divisibility of matter was arraigned by Hume as so far from being a truth, that it was not even capable of being conceived by the mind, which had never yet received any impressions through the senses corresponding to the expression. Every man had seen matter divided—some into smaller fragments

than others; but where our ideas, derived from actual experiment, stopped in minuteness of division, the conception of divisibility stopped also. The truth of geometrical demonstration, as applicable to practice, he did not deny; but he maintained, or rather seemed to maintain, for his reasoning here is of a highly subtle order, that we have a conception of these operations only in as far as they concur with really existing things, or, more properly speaking, with the ideas in the mind conveyed thither by the senses. Of the point, which has no breadth, depth, or length; of the straight line, which is deficient in the first and second, and not in the last of these qualities, he denied that we could have an idea, unless that idea were just as much the representative of an actual existence as any other idea is.

Infinity of space was an expression to which he had an objection on similar grounds; it had no idea corresponding to it lodged in the mind. Of space finite in various quantities, the mind possessed ideas stored up from repeated impressions, and by adding these ideas together, more or less vastness in the conception of finite space was afforded. But any thing beyond this definitive increase, attested as it was by the senses, the mind had no means of conceiving. Whatever might be in another intellectual world, there was no idea corresponding to infinity of space in the mind of man. It thence followed, that space unoccupied was a conception of which the mind was incapable, because the impressions originally conveyed to the mind were the medium through which the conception of space existed, and where there were no ideas of such impressions, an aggregate idea of space was wanting. In the same manner it was held, that it was in a succession of impressions, with ideas corresponding, that

the conception of time consisted, and that without such a succession, time would be a thing unknown and unconceived. Our ideas of numbers he found to be but the collected ideas of the impressions of the units of which the senses have received distinct impressions; and in confirmation of this he appealed to the distinctness of our notion of small numbers, which our mind has been accustomed to find represented by units, and our imperfect conception of those large numbers, which we have never had presented to us in detail. How readily we have a notion of six, but how imperfectly the mind receives the conception of six millions; how clearly we perceive, in units, the difference between six and twelve, but how imperfect is our notion of the difference between six millions and twelve millions.[75:1]

All human consciousness being of these two materials, impressions and ideas, the answer to the question, What knowledge have we of an external world, resolved itself into this, that there were certain impressions and ideas which we supposed to relate to it—further we knew not. When we turn, according to this theory, from the external world, and, looking into ourselves, ask what certainty we have of separate self-existence, we find but a string of impressions and ideas, and we have no means of linking these together into any notion of a continuous existence. Such is that boasted thing the human intellect, when its elements are searched out by a rigid application of the sceptical philosophy of Hume. Not a thing separate and self-existent, which was, and is, and shall continue; but a succession of mere separate entities, called in one view impressions, in another ideas.[76:1]

It may make this brief sketch more clear, to notice a circumstance in the history of philosophy, which, perhaps, serves better in an incidental manner to mark the boundaries of the field of Hume's inquiry, than many pages of discursive description. The transcendentalists took him up as having examined the materials solely, on which pure reason operates;

not pure reason itself. They said that he had examined the classes of matter which come before the judge, but had omitted to describe the judge himself, the extent of his jurisdiction, and his method of enforcing it. They maintained, that all these things, which with Hume appeared to be the constituent elements of philosophy, were nothing but the materials on which philosophy works,—that to presume them to be of service presupposed a reason which could make use of them,—that Hume himself, while thus speculating and telling us that his mind consisted but of a string of ideas, left behind by certain impressions, was himself making use of that pure reason which was in him before the ideas or impressions existed, and was through that power adapting the impressions and ideas to use. He characterized his system as "an attempt to introduce the experimental method of reasoning into moral subjects:" but they said that there was another and a preliminary matter of inquiry—the faculty, to speak popularly, which suggested what experiments should be made, and judged of their results.

Hume may be found indirectly lamenting the fate of his own work on metaphysics, in his remarks on other works of a kindred character; and in these criticisms we have a clue to the expectations he had formed. In his well-known rapid criticism on the literature of the epoch of the civil wars, he says of Hobbes: "No author in that age was more celebrated both abroad and at home than Hobbes. In our times, he is much neglected: a lively instance how precarious all reputations founded on reasoning and philosophy! A pleasant comedy which paints the manners of the age, and exposes a faithful picture of nature, is a durable work, and is transmitted to the latest posterity. But a system, whether physical or metaphysical, owes commonly its

success to its novelty; and is no sooner canvassed with impartiality, than its weakness is discovered."

Like the majority of literary prophecies dictated by feeling and not by impartial criticism, this one, whether as it refers to "The Leviathan," of which it is ostensibly uttered, or to the "Treatise of Human Nature," the fate of which doubtless suggested it, has proved untrue. The influence of Hobbes has revived, as that of the Treatise remained undiminished from the time when it was first fully appreciated. And in both cases their influence has arisen from that element which seems alone to be capable of giving permanent value to metaphysical thought. It is not that in either case the fundamental theory of the author is adopted, as the disciples of old imbibed the system of their masters, but that each has started some novelties in thought, and, either by themselves sweeping away prevailing fallacies, or suggesting to others the means of doing so, have cleared the path of philosophy. As a general system, the philosophy of Hobbes has been perhaps most completely rejected at those times when its incidental discoveries and suggestions made it most serviceable to philosophy, and were the cause of its being most highly esteemed. "Harm I can do none," says Hobbes, when speaking of the metaphysicians who preceded him, "though I err not less than they, for I leave men but as they are, in doubt and dispute." There is indeed nothing in the later history of metaphysical writing to show that the triumphs in that department of thought are to stretch beyond the establishment of incidental truths, the removal of fallacies, and the suggestion of theories that may teach men to think. The field is a republic: incidental merit has its praise, and is allowed its pre-eminence; but no one mind, it may safely be pronounced, holds