1852. The Methods' of Bacon and Descartes.

43

cisely the same method which England has been eager to 'attribute exclusively to Bacon.' 'It is impossible,' says Playfair, that two men could pursue the same ends by methods 'more diametrically opposite.' Between these very diverse statements it is possible in some measure to diminish the enormous interval by proper explanations; for what may not be explained, or explained away? but there will be little doubt with any dispassionate person, who has studied the writings of both philosophers, that the statement of Playfair is far nearer the truth.

Each of these great philosophers, indeed, was deeply imbued with the importance of a Method; and each recognised, though in inverse proportions, the necessity of both induction and deduction in rearing the fabric of science. It is not more true that Bacon (in passages candidly cited by Cousin *) admits the value and necessity of a provisional anticipation' of nature as the only rational guide of that observation and experiment which alone can give the 'interpretation' of nature, than it is that Descartes insists on the necessity of experiments as a condition of the verification of the truth of scientific deduction, and even insists on their being more necessary at every step, as the conclusions of science become more intricate, and the elements with which it has to deal more subtle. The reader will find some remarkable passages to this effect at the close of his 'Method';† and in this anticipation we are by no means sure that he is not right, notwithstanding the confident expectations indulged by many that as induction advances, and the data for deduction become more and more sure, this last will in its turn reverse the proportions in which the true interpretation of nature has hitherto employed both instruments, and become the more important of the two. That deduction will have ampler and ampler scope, and become of more and more utility, we have no doubt; that it will do its peculiar work better and better, we have as little; but we still doubt whether it will not continually demand or suggest new exercises for induction in full proportion to every truth it proves or confirms. The reasons for suspecting this we will briefly touch by and by.

But though it is true that neither Bacon nor Descartes in strictness disclaimed the necessity or utility of either of these instruments of prosecuting science, the instruments themselves occupied in their two systems the most dissimilar positions; there can hardly be a question that Bacon's estimate was the

* Cours de Philosophie; Histoire: Onzième Leçon.
† Sixième Partie, pp. 40, 41. (Edition of M. J. Simon.)

more correct of the two. In his system, induction was first, first in order and importance; that without which man could not proceed a single step in physical science; in that of Descartes deduction from assumed principles came first; induction and experiment were only ministering organs. It was the glory of Bacon (and it was virtually a great triumph of mental philosophy as well as a noble example of that very induction from physical facts, the claims of which he asserted,) that he saw clearly, both from observation and consciousness, that the mind of man was so constituted in relation to external nature such its limitations and conditions of thought-that it could not, for the most part, anticipate at all, and never with absolute precision and certainty, without the verification of observation and experiment, what facts were connected with what other facts; what consequents would follow from any given antecedents; in other words, that man could not construct the premises from which, in physical science, he could certainly deduce his conclusions. It was the error of Descartes, on the other hand, that he reversed the proportions assigned to the influence of this predominant element in Bacon's method; and believed that man could construct his premises and deduce his conclusions from them; that man could, as he expressly declares, and, if a true philosopher, ought to deduce effects from causes,' and not collect causes from effects.' But it would be unjust to both to forget what has been said, that neither looked upon that element to which he gave a secondary place as of absolutely little importance. Descartes, as already hinted, not only thought that experiment was perpetually necessary to test and verify the results of deduction; but that it would be more so as science advanced, on account of the increasing complexity of the phenomena to be investigated, and the sources of fallacy which lurk, in what Mr. Mill has so aptly named, ‘Intermixture ' of Effects and Plurality of Causes.' This admission itself

affords the strongest condemnation of the order of investigation pursued by Descartes; for how many hypotheses might be framed and discarded before man arrived at the only one which experiment and observation would thus verify! how many anticipations of nature must go to make up one true and authentic interpretation! This indeed is a reflection, the justice of which the melancholy history of all philosophy, when pursued as Descartes suggests, has abundantly exemplified.

Descartes,' says Playfair, in a very lively passage, 'did not reject experiment altogether, though he assigned it a very 'subordinate place in his philosophy. "We employ experi"ment, says he (Descartes) not as a reason by which anything

1852.

Induction and Deduction.

45

"is proved, for we wish to deduce effects from their causes, ❝"and not conversely causes from their effects. We appeal to "experience only, that out of innumerable effects which may ""be produced from the same cause, we may direct our atten""tion to one rather than another." It is wonderful that Descartes did not see what a severe censure he was here pass'ing on himself; of how little value the speculations must be 'that led to conclusions so vague and indefinite; and how much more philosophy is disgraced by affording an explanation of things which are not than by not affording the explanation of things which are.'

6

On the other hand, it would have been a gross error in Bacon had he ever intended to imply that 'anticipation' of some results rather than others, was not to preside over all experiment and observation; without which, indeed, in the vast majority of instances, it were utterly impossible that man should be adequately impelled to devise experiments' or to persevere in 'observation. This anticipation' is the very spur of that curiosity, without which great genius would not submit, with patience, to be the mere interpreter of nature, and its reluctance would grow stronger and stronger, the more deep the truth sought, and the more refined the instruments required to extort it. In torturing' nature, as Bacon has it in his strong imagery, man would, in such a drudging office, torture himself still more; and his indolence would get the better of his philosophy. And, in truth, as there must always be not only scope, but a necessity for such provisional anticipation, so there would be neither dignity nor merit in scientific discovery without it; men would say there was great good luck in a discovery rather than great sagacity. The achievements of scientific genius are measured not so much by the magnitude of a discovery (at least in the estimate of all thinking men) as by the approximate accuracy-it is seldom more-of the anticipated results; and it is this prophetic instinct of science— an 'anticipation' of nature, which in certain points is indefinitely near the true interpretation,'-this seer-like utterance of her oracles though it may be in lisping accents and a stammering tongue' -which constitutes the glory of the successful philosopher. Bacon must not, therefore, be supposed for a moment to have undervalued the necessity for provisional anticipations'; although, intent on inculcating the paramount importance of induction, he may have sometimes seemed to depreciate their value.*

* We earnestly recommend to every student of philosophy, some

He was certainly opposed to no 'anticipations' of nature which do not involve (what he was chiefly anxious to guard against) the abuse of hypothesis, the disposition of philosophers to make it, not a light and loose garment to be thrown on and off at pleasure, but their very skin; their proneness to force their conceptions on Nature, whether she will or not, and to tell her that they know her better than she knows herself. As to the use of hypothesis, and the vanity of blind and unintelligent inquiry at Nature's oracles, no one can be more explicit than Bacon himself; or speak with more contempt of that vaga ' experientia quæ mera palpatio est.' A just image of the empirical philosopher who confounds induction with the 'mera palpatio' would be a man admitted to an immense laboratory of all sorts of chemicals some more simple and some lessand essaying discovery by going round the shelves and amusing himself with pouring a little out of one box or phial into any other, as their proximity or his own eye or fancy suggested, just to see what would come of it. Now if he did not. manage to choke himself with some unhappy evolution of gases, of which he had had no anticipation,' nor could give any in'terpretation;' or blind himself with some equally novel and brilliant explosion of inflammable substances; or poison himself with some subtle exhalation, there is no doubt but he might chance to stumble on some singular discovery; upon none, however, greater than the discovery that he would not know what he had discovered. On the other hand, if he made no discovery, nobody would be surprised; nor, lastly, concede him any merit if he did.

We return to the subject postponed a page or two back. Though it is evident that deduction will play a more and more important part as science advances, because it will have wider and wider bases of inference before it, it may still be doubted whether it will ever we do not say supersede, but even much diminish the necessity for induction and experiment; whether, in fact, Descartes' view is not near the truth. One may suspect this, not merely because (as Mr. Mill properly says) deduction must presuppose and demand induction-not only because the deductive process (to make it worth anything) will ever demand verification, which itself involves an appeal to induction; nor merely because as the data of deductive inference become more and more extensive and complex, the inferences themselves (as the same writer observes) involve an analysis and computations

excellent remarks by Mr. Mill, on the subject of Hypothesis. (Logic, vol. ii. ch. 14.)

1852. Conjunct Employment of Hypothesis and Experiment. 47

which can rarely be performed with more than approximate accuracy;-not only, we say, for these reasons, but for another and more direct one. It is this: that the results of the deductive process, being rarely more than approximations to complete solution, with whatsoever sagacity and subtlety conducted, will often require to be rectified as well as verified by further observation; the very attempt to verify them will often reveal previously unsuspected residual phenomena, which ought not to exist, if both data and deduction were complete, and suggest an entirely new series of experiments and observations to adjust the theory to the facts.*

Though, therefore, the triumphs of deduction may be continually more splendid, those very triumphs will, in all probability, disclose new fields for the achievements of induction.

In short, in the attempt to unravel completely any considerable portion of the great web of the universe, much more of the whole, induction and deduction may, for aught we know, reciprocally involve one another in an interminable progression ; so far, according to Bacon's sublime language, does the subtlety of nature surpass the subtlety either of sense or intellect.' Thus will man be ever tied, as a condition of advancement, to observation and experiment; deduction will always be preceded and accompanied by them, and never be independent of them; while the most sagacious conjectures will still end with the Queen of Sheba's exclamation, The half hath not been told me.' And surely man may well be contented with his sublime, though he is sometimes apt to think it, humble office of interpreter of nature. It is enough for him. To what greater glory can the creature aspire than that of being the interpreter of his Creator? to decipher those hieroglyphics which are symbols-though but imperfect symbols-of the Infinite One? There is no sublimer passage of poetry in the world than that in Job (to which far from justice is done in our translation), in which the Patriarch, after having enumerated even the splendours with which God has garnished the heavens,' and the art with which He has hung the world upon nothing,' exclaims, How slight is the

*See the striking observations of Mr. J. S. Mill on the subject of the Method of Residues,' with the beautiful illustrations from Sir John Herschel. (Mill's Logic, vol. i. p. 501.) Mr. Mill's observations on Residual Phenomena, are made, indeed, in reference to the results of the experimental methods of inquiry; but similar observations seem applicable to many results of the deductive process. See Sir J. Herschel's Discourse, pp. 174-5., for some striking remarks on the alternate use of these instruments.