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nings himself, any should be found capable of passing the terrible ordeal. But I confess I am quite unable to see the necessity of making such impossible demands upon the human intellect. Surely, to recur to the example taken from Adam Smith, it is possible to perceive that division of labour, and exchange, facilitate the production of wealth, without deciding whether the disposition which leads to this course of conduct be an original or derived faculty ; or to understand the advantages which the precious metals offer as a measure of value and medium of exchange, though we may be wholly ignorant whether they are simple or complex substances, or appear at the positive or negative pole of the battery. Or, to take an example from Mr. Jennings' book, I confess I am quite unable to see what new light is thrown upon the causes which determine the labourer's condition, by his telling us that during “ production the instrumentality of the efferent trunks of nerve-fibre is predominant,” while, during “consumption” it is “the afferent trunks of nerve-fibre which prevail.” So long as the result is the same, so long as human beings possess the same energies, require the same subsistence, and are influenced by the same motives, the economic laws of wages will be the same, though they had neither “afferent” or “efferent” trunks of nerve-fibre in their bodies. Even were the encyclopædic knowledge, demanded by Mr. Jennings, easily attainable, it appears to me that nothing but confusion and error could arise from extending economic inquiry beyond the limits which have hitherto been observed. Take, e. g. the division of industrial operations which I have quoted above from Mr. Jennings, founded upon his analysis of the mental principles engaged, what is the economic value of this classification? What light does it throw on the production and distribution of wealth ? Mr. Jennings places in the same class of “industrial operators,” judges, and legislators, because the actions in which they engage are “marked by the application of judgment and resemblance to the merely memorial trains of thought;": but, economically considered, if it be desirable to class them at all, judges are far more widely separated from legislators than from “superintendents,” or from “diggers, threshers, rowers, or sawyers,” who are placed in distinct classes ; judges being highly paid officers, while legislators (at least in this country) instead of being paid, are obliged to pay handsomely to be allowed to exercise their functions. If a judge be paid more highly than a digger, it is not because the exercise of the functions of the latter involve only “memorial trains of thought,” while the exercise of those of the former involve besides the faculties of judgment, and of perceiving analogies--this, economically considered, being an accident; but because the persons who are qualified to perform the functions of a judge are much fewer than those who are qualified to dig ; and the reason the former are more scarce is partly because the requisite natural faculties are more rare, and partly because the expense necessary to their due cultivation is considerable.
Classification will, I presume, be more or less perfect in proportion as it is founded upon those qualities in the objects of it, which, with reference to the ends of the science, are essential; but a classification, based upon an analysis of the psychological or physiological operations which take place in the production or distribution of wealth, will not divide producers or distributors according to their economic importance, but according to circumstances which, economically considered, are purely accidental.
The following passage from Dr. Whewell's History of the Inductive Sciences contains so elegant an example of the logical process by which the great generalizations in physical science are established, that, with a view to illustrate some occasional references to the line of reasoning pursued in physical investigations which occur in the text, I am induced to extract it.
“When we look at the history of the emission-theory of light, we see exactly what we may consider as the natural course of things in the career of a false theory. Such a theory may, to a certain extent, explain the phenomena which it was at first contrived to meet ; but every new class of facts requires a new supposition,-an addition to the machinery ; and as observation goes on, these incoherent appendages accumulate, till they overwhelm and upset the original frame-work. Such was the history of the hypothesis of solid epicycles ; such has been the history of the hypothesis of the material emission of light. In its simple form, it explained reflection and refraction ; but the colours of thin plates added to it the hypothesis of fits of easy transmission and reflection ; the phenomena of diffraction further invested the particles with complex hypothetical laws of attraction and repulsion ; polarization gave them sides ; double refraction subjected them to peculiar forces emanating from the axes of crystals ; finally, dipolarization loaded them with the complex and unconnected contrivance of moveable polarization ; and even when all this had been assumed, additional mechanism was wanting. There is here no unexpected success, no happy coincidence, no convergence of principles from remote quarters : the philosopher builds the machine, but its parts do not fit; they hold together only while he presses them : this is not the character of truth.
In the undulatory theory, on the other hand, all tends to unity and simplicity. We explain reflection and refraction by undulations; when we come to thin plates, the requisite 'fits,' are already involved in our fundamental hypothesis, for they are the length of an undulation : the phenomena of diffraction also require such intervals ; and the intervals thus required agree exactly with the others in magnitude, so that no new property is needed. Polarization for a moment checks us ; but not long ; for the direction of our vibrations is hitherto arbitrary ;we allow polarization to decide it. Having done this for the sake of polarization, we find that it also answers an entirely different purpose, that of giving the law of double refraction. Truth may give rise to such a coincidence ; falsehood cannot. But the phenomena became more numerous, more various, more strange ;—no matter : the theory is equal to them all. It makes not a single new physical hypothesis ; but out of its original stock of principles it educes the counterpart of all that observation shows. It accounts for, explains, simplifies, the most entangled cases ; corrects known laws and facts; predicts and discloses unknown ones ; becomes the guide of its former teacher, observation ; and, enlightened by mechanical conceptions, acquires an insight which pierces through shape and colour to force and cause." -History of the Inductive Sciences, vol. 2, p. 464-6.
This circuitous mode of proof, indispensable in physical inquiries, is (as I have endeavoured to show in my third lecture) superseded in economic investigations by proof of a more direct, and therefore unequivocal character.