« ForrigeFortsæt »
whisper that we hear of him! But the thunder of his power who can comprehend?'
Even the felt necessity, however, of verification, for every result of deduction, shows how completely, from the very constitution of his nature, man is tied down to experiment and observation; and how, unless these authenticate his antici'pations,' all he achieves by the other instrument goes for nought, if it is to pass as a declaration of what is. Take the case of Halley's wonderful prophecy of the periodic time of what is naturally called his comet. If we may suppose (what was by no means impossible) that during several successive years of its predicted return, clouds had obstinately filled the sky, and concealed it from the astronomer's gaze, would the world have given absolute faith to the predictions? No verily; it would have been said; If the comet does indeed move in the exact path and observe the prescribed laws of your calculation, it will have returned, though we saw it not; but there are so many ' unknown causes,' (some, indeed, which modify Halley's antici'pations have been discovered since,) which may vitiate the result, that we cannot accept it as a fact, till we observe the 'comet's return. Your calculations are all hypothetically true; they tell us what may be, but they must not assure us of what 6 is, till fact itself has confirmed them.'
The rules which Descartes, as well as Bacon, have given for the prosecution of scientific discovery - the one more particularly in relation to the process of induction, and the other to that of deduction-may seem of very little use as directly applied to the purposes for which they were more immediately designed; and perhaps no great discovery was ever made by the mechanical or deliberately conscious application of either. Yet it would be a most fallacious conclusion that they are of no utility at all; and far greater would be the error of concluding the like in relation to the general observations (such as those in the immortal first book of the NOVUM ORGANUM), which tend to forewarn the mind itself of the points in which an ambush of error may be suspected; to guard it against the easily besetting prejudices which spring from its very constitution, or have been contracted in the course of its development; and to remind it during the course or in the review of its operations, to ask whether certain points have been guarded, certain cautions observed, certain known conditions complied with. Such observations, when well founded, however unsusceptible of a direct application to the discovery of an unknown truth, or explanation of an unknown phenomenon, tend by a general influence to rectify the position of the mind. They
1852. Rules for the Use of the Human Understanding.
are not (if we may borrow a metaphor from astronomy) the telescope by which the star we seek is revealed, but they enable us, as astronomers say, to allow for the aberration of light, and to adjust the instrument in the right position for observation. There are some admirable sentences in Mill's
Logic applicable to this subject. There is not,' says he, 'pro'perly an Art of Observing. There may be rules for observing. But these, like rules for inventing, are properly instructions 'for the preparation of one's own mind; for putting it into the 'state in which it will be most fitted to observe, or most likely to invent. They are, therefore, essentially rules of self' education, which is a different thing from Logic. They do not teach how to do the thing, but how to make ourselves 'capable of doing it. They are an art of strengthening the 'limbs, not an art of using them.'
Viewed in any other light, the four meagre rules of Descartes mentioned in his Method,' or even the more elaborate one and twenty in his posthumous Régles pour la direction de l'esprit,' seem rather useless. Of most of them we might make a remark somewhat similar to that of Descartes himself on his celebrated criterion, that the things we conceive clearly and distinctly 'must be all true;' on which, he naïvely adds, there is only 'some little difficulty in thoroughly determining what are the 'things which we conceive distinctly;' a point which, considering what thoughts not only the vulgar, but philosophers of the thousand and one sects, have supposed to be clear and distinct, is a little perplexing. Of all the four rules given in his Method' one may certainly be justified in saying what M. Cousin remarks of one of them: They are very important and I very wise, but more easy to recommend than to follow.' The first is never to accept anything as true which is not clearly known to be such;' the second, to divide each difficulty under 'examination into as many parts as may be requisite for its solution; the third, to conduct the thoughts in order, commencing with the simplest objects and proceeding to the more complex ;' and the fourth, 'to make enumerations so complete
* This_work contains many admirable observations of that more general character to which we have above adverted; tending to enlarge and rectify the conceptions under which the mind may set about philosophising; to exercise a pervading influence over the habits of thought; to inspire, in a word, the philosophic spirit. Considered as a specific apparatus designed for conscious application in the attempt to elicit scientific truth, it is, for the reasons assigned, unsatisfactory; viewed in any light, perhaps it scarcely merits the high eulogium M. Cousin has passed upon it.
VOL. XCV. NO. CXCIII.
and surveys so general, as to be certain that nothing is omitted." (Method, Part II.)
It is evident that both Bacon and Descartes thought that a system of rules might be devised which would do much more than any such system can; which, in fact, would wonderfully diminish that interval which must ever subsist between a great genius and a great blockhead. How exactly does the following passage from Descartes's Régles pour la direction de ' l'esprit' coincide with certain well-known passages of the NOVUM ORGANUM.' 'Or dans tout ce traité nous tâcherons 'de suivre avec exactitude et d'aplanir les voies qui peuvent conduire l'homme à la découverte de la vérité, en sorte que l'esprit le plus médiocre, pourvu qu'il soit pénétré profondément ' de cette méthode, verra que la vérité ne lui est pas plus inter'dite qu'à tout autre, et que, s'il ignore quelque chose, ce n'est faute ni d'esprit ni de capacité.'
The illustrations which they have both used in reference to a wrong' and a 'right' method (so singularly similar that it is difficult not to suppose that the one was suggested by the other) are indeed true enough. 'A cripple in the right road,' says Bacon, will beat a racer in the wrong;' Those who walk slowly,' says Descartes, will make faster progress, if they ' pursue the right road, than those who run swiftly, if they run ' in a wrong one.' But then a cripple, even in the right road, will be but a cripple still. For the actual advancement of science, for making any new discoveries where they are made, (and are not mere accident,) so much is necessary to be drawn ex visceribus causa; so much more depends on individual sagacity in relation to the special circumstances than on any general rules whatever; nay, so much sagacity is even required to derive any benefit from rules themselves, that though blockheads may acquire what genius has once discovered, only genius could discover it. It is, indeed, quite true (to use Bacon's illustration) that the most unskilful hand with a pair of compasses will draw a more exact circle than even the most adroit and practised hand without them; but the compasses are yet to be invented, which will enable an ordinary intellect to be a great scientific discoverer. If, indeed, the comparison be between genius with rules and genius without them, then, cæteris paribus, we cannot but think that he who has pondered deeply a system in which the general conditions of investigation are accurately described, and the principal sources of error pointed out, will have an immense advantage over him who has no knowledge of the kind; less, indeed, from any possibility of a deliberate or mechanical application of any maxims, than from the unconscious
Cartesian View of Brutes.
but diffusive influence they exert on the general habits of thought.
We had intended offering some remarks on some other points. in Descartes's philosophy; especially on the prominence he gave to the notion of substance compared with that of cause, and the confusion by which he represented conservation and creation as the same act ; —by which his system, it is affirmed, was successively developed or distorted into those of Malebranche, Spinosa, and Leibnitz. But our space forbids; and we must content ourselves with referring to the acute remarks of M. Cousin* and M. Jules Simon.†
But there is one subject on which we cannot prevail upon ourselves to be wholly silent. We allude to the opinions of Descartes in relation to the lower animals: certainly among the most paradoxical of his somewhat eccentric genius. Not that it is perfectly clear what he did hold, and certain that he did not hold the extreme opinion which is sometimes attributed to him; that is, that animals are not only automata, inasmuch as they are supposed to be destitute of intelligence and volition, but that they are destitute of all feeling, and therefore may be kicked and cuffed, certainly dissected and experimented upon for the benefit of philosophy, ad libitum. If that were true, nothing could be more reasonable than the sang-froid with which a Majendie might torture animals for the advancement of science; nor anything more unreasonable than the Society for the Prevention of Cruelty to Animals; —a society which, if the views of some interpreters of Descartes were correct, would be of about the same utility as a hospital for blighted shrubs or cases of potato disease. The truth is, however, that Descartes did not go this length. There are expressions indeed, which would almost justify the supposition, were it not for others of a contrary tendency; and perhaps if his principles with regard to the mechanical origin and exhibition of the phenomena of sentient life in the lower animals were logically carried out, he ought, in consistency, to have proceeded to this extravagance. But, in fact, with all his incomparable powers of expression, there is not, as in the case of his varying language on the subject of innate ideas,' that steadiness in the utterance of his views, given at different times and to meet various objections, which could be wished.
It is wonderful that with so clear a perception, and on such strong grounds, of the distinction between matter and mind, he
* Cours de Philosophie; Leçon Onzième.
should have associated the appearances of sensation, conception, appetite, and emotion in the brutes, rather with the phenomena of the former than with those of the latter; and most of all; that he should have done so when he had defined 'chose pensante,' as including the idea of une chose qui sent.' This being the case, it seems, as Gassendi has remarked, incomprehensible, that even denying intelligence and volition to brutes, the phenomena in which they resemble ourselves should be all attributable to material causes and mechanical laws.*
He supposes (to employ his wonted illustration) that an indefinitely skilful artificer might construct out of matter, and by purely mechanical laws, automata exhibiting all the phenomena observed in brutes, and, by parity of reasoning, all that we observe in man- the pensée to which exclusively he arrogates immateriality, alone excepted; —only, as already shown, he somehow strangely conjoins in men the qui sent' with the qui pense.'† Either he should have found sensation in man
* Even putting sensation out of the question, and looking only at the profound mystery, which still baffles all physiologists-animal life, it is amusing to see with what ease Descartes accounts for its phenomena by the rudest mechanical and chemical hypotheses. Thus, in his perspicuous, and to so great extent accurate, account of the circulation of the blood, in the fifth part of the 'Method,' he supposes that the alternate dilatation and contraction of the heart is all satisfactorily accounted for by the supposition of heat, and its expansive power. This heat he supposes to be exactly the same as that evolved in fermentation. It is also evident that Descartes, with his imperfect conceptions of chemistry and physiology, thought, not merely that mechanical laws would much more easily and satisfactorily account for the phenomena of animal life-and even for the appearances of sensation, passion, and association exhibited by the lower animals. than they ever will; but that there was a far less complicated and subtle apparatus for uniting in man the kingdoms of mind and matter, the corporeal and the spiritual, than nature has really provided. In short, he thought that, being perfectly distinct, they were divided by a broad and well-defined frontier line, instead of exhibiting as they do, such subtle and refined interaction; rendering it impossible to say, even now, how many mysteries of how many sciences may be involved in the entire production and manifestation of their inextricable phenomena.
In the following paragraph of a letter to Henry More, who vehemently reluctated against this article of the Cartesian philosophy, he frankly states this infirmity in his Logic, which, however, he does nothing to remedy: 'I see no reason for supposing thought in brutes except this only; that since they have eyes, ears, tongues, and ' other organs like ours, it is very probable that they feel as we do; and since in our mode of sensation, thought is included, thought