Life and Correspondence of David Hume, Volume 1

by John Hill Burton

in it that monarchical sway which Adam Smith retains over the empire of political economy. The ancient systems anterior to Christianity allowed of such empire. The pupil did not follow his master merely in this and that incidental truth developed, but adopted the system in all its details and proportions as his system and his creed. In later times it would probably be found that the most devoted admirers of great writers on metaphysics do not adopt their opinions in the mass; and it seems that men must now go elsewhere than to the produce of human reason, for the grand leading principles of the philosophy of belief and disbelief.

To those who hold that the writings of the great metaphysicians are thus to be esteemed on account, not of their fundamental principles, but of the truths they bring out in detail, a new theory is like a new road through an unfrequented country, valuable, not for itself, but for the scenery which it opens up to the traveller's eye. The thinker who adopts this view, often wonders at the small beginnings of philosophical systems—wonders, perhaps, at the circumstance of Kant having believed that his own system started into life at one moment as he was reading Hume's views of Cause and Effect. But the solution is ready at hand. We feel that the philosopher of Königsberg had in his mind the impulses that would have driven him into a new path had no Hume preceded him. We owe it to the Essay on Cause and Effect that it was the starting-point at which he left the beaten track; but, had it not attracted his attention, his path would have been as original, though not, perhaps, in the same direction. And so of Hume himself. If the main outline of his theory had never occurred to him, he would still have been a great philosopher; for in some form or other he would have

found his way to those incidental and subsidiary discoveries, which are admitted to have reality in them by many who repudiate his general theory.

Of all the secondary applications of the leading principle of the Treatise, none has perhaps exercised so extensive an influence on philosophy, as this same doctrine of cause and effect. Looking to those separate phenomena, of which in common language we call the one the cause of the other, and the other the effect of that cause, he could see no other connexion between them than that the latter immediately followed the former. He found that the mind, proceeding on the inductive system, when it repeatedly saw two phenomena thus conjoined, expected, when that which had been in use to precede the other made its appearance, that the other would follow; and he found that by repeated experiment this expectation might be so far strengthened, that people were ready to stake their most important temporal interests on the occurrence of the phenomenon called the effect, when that called the cause had taken place. But if there were any thing else but this conjunction, of which a knowledge was demanded—if the unsatisfied investigator sought for some power in the one phenomenon which enabled it to be the fabricator of the other—the sceptical reasoner would answer, that for all he could say to the contrary such a thing might be, but he had no clue to that knowledge—no impression of any such quality passed into his intellect through sensation—his mind had no material committed to it by which the existence or non-existence of any such thing could be argued.

The vulgar notion of this theory was, that it destroyed all our notions of regularity and system in the order of nature; that it made no provision for

unseen causes, and contemplated only the application of the doctrines of cause and effect to things which were palpably seen following each other. But the inventor of the theory never questioned the regularity of the operations of nature as established by the inductive philosophy; he only endeavoured to show how far and within what limits we could acquire a cognizance of the machinery of that regularity. He denied not that when the spark was applied, the gunpowder would ignite, or that when the ball was dropped, it would proceed to the earth with the accelerated motion of gravitation; but he denied that we could see any other connexion between the cause and effect in either case, than that of uniform sequence. When it was scientifically adopted, the theory was found to be productive of the most important results. The view that when any effect was observed, that phenomenon which was most uniform in its precedence was the one entitled to be termed the cause, was a salutary incentive to close and patient investigation, by laying before the philosopher the simple, numerical question—what was that phenomenon which, by the uniformity of its precedence, was entitled to be termed the cause?[81:1] The test became of the simplest kind; and, if the experimentalist had at a particular time considered some phenomenon as a cause,—if the farther progress of patient and unprejudiced inquiry showed that

another, by the occurrence of instances in which it preceded the effect while the former did not, had a preferable title to be termed the cause, the mind in its unbiassed estimate of numbers at once admitted the claim. But when, according to the antagonist system,[82:1] it became settled that any given phenomenon had in it the power of bringing into existence another, that power was viewed as a quality of the object. When things are admitted to have qualities, it is not easy for the mind at once to assent to their non-existence and to admit that others have the proper title to these qualities. Analogy, the great source of fallacies, comes to increase the difficulty, by a confusion of what are termed the qualities of bodies, and those endowments with which we invest our fellow-creatures. In this respect Hume's theory of cause and effect has been of great service to inductive philosophy.

It was an objection to it that it made no allowance for unseen causes; but it was part of its author's system, that the uniformity which our observation teaches us, proceeds unseen in those cases to which our observation cannot penetrate. It was part of the theory, that where there is a want of the absolute uniformity in the sequence of two phenomena, they are not respectively cause and effect. This principle is of vital importance in physical science. It is a notion with the vulgar, and one that sometimes perhaps lurks unseen in scientific operations, that the cause sometimes does not produce its effect by reason of some failure in the operating power. It is from a vague amplification of this heresy, that the popular

notion of chance is derived. Hume's theory nips the bud of such a fallacy by denying, whenever there is a break in the sequence, that the phenomena which have in other instances followed each other, really are cause and effect. It is perhaps in the unscientific application of therapeutics, that the popular fallacy is most widely and most dangerously exemplified. The whole of the complexity of that wondrous science consists in the immediate causes and effects being unseen—in the phenomena immediately conjoined not being ascertained, but in attempts being made to estimate them through the connexion between those external causes to which the internal causes may have had the relation of effects, and those external effects of which these internal effects may have been the causes. The character of unseen causes was aptly illustrated by Hume himself, from the throwing of a die. The vulgar mind can see no cause and effect in the operation, because there is a series of causes and effects, which are hidden from the sight, in the interior of the box; but the philosopher knows not the less, that those laws of motion, which induction has established to him as truths, are taking place; and that there is no turn made by the die, which is not as much the effect of some cause, as the turning of the hands of a watch, or the parallel motion in a steam engine.

It is one of the peculiar features of the history of mental philosophy, that there is scarcely ever a new principle, associated with the name of a great author, but it is shown that it has been anticipated, in some oracular sentence, probably by an obscure writer. Joseph Glanvill is pretty well known as the author of "Saducismus Triumphatus," a vindication of the belief in witches and apparitions, which must have been perused by all the curious in this species of lore.