But while the prevalence of crude political opinions among those whose conceptions about simple matters are so crude, might be anticipated, it is surprising that the class disciplined by scientific culture should bring to the interpretation of social phenomena, methods but little in advance of those used by others. Now that the transformation and equivalence of forces is seen by men of science to hold not only throughout all inorganic actions, but throughout all organic actions; now that even mental changes are recognized as the correlatives of cerebral changes, which also conform to this principle; and now, that there must be admitted the corollary, that all actions going on in a society are measured by certain antecedent energies, which disappear in effecting them, while they themselves become actual or potential energies from which subsequent actions arise; it is strange that there should not have arisen the consciousness that these highest phenomena are to be studied as lower phenomena have been studied – not, of course, after the same physical methods, but in conformity with the same principles. And yet scientific men rarely display such a consciousness.
A mathematician who had agreed or disagreed with the view of Professor Tait respecting the value of Quaternions for pursuing researches in Physics, would listen with raised eyebrows were one without mathematical culture to express a decided opinion on the matter. Or, if the subject discussed was the doctrine of Helmholtz, that hypothetical beings occupying space of two dimensions, might be so conditioned that the axioms of our geometry would prove untrue, the mathematician would marvel if an affirmation or a negation came from a man who knew no more of the properties of space than is to be gained by daily converse with things around, and no more of the principles of reasoning than the course of business taught him. And yet, were we to take members of the Mathematical Society, who, having severally devoted themselves to the laws of quantitative relations, know that, simple as these are intrinsically, a life’s study is required for the full comprehension of them – were we to ask each of these his opinion on some point of social policy, the readiness with which he answered would seem to imply that in these cases, where the factors of the phenomena are so numerous and so much involved, a general survey of men and things gives data for trustworthy judgments.
Or, to contrast more fully the mode of reaching a conclusion which the man of science uses in his own department, with that which he regards as satisfactory in the department of politics, let us take a case from a concrete science: say, the question – What are the solar spots, and what constitution of the Sun is implied by them? Of tentative answers to this question there is first Wilson’s, adopted by Sir William Herschel, that the visible surface of the Sun is a luminous envelope, within which there are cloudy envelopes covering a dark central body; and that when, by some disturbance, the luminous envelope is broken through, portions of the cloudy envelope and of the dark central body, become visible as the penumbra and umbra respectively. This hypothesis, at one time received with favour mainly because it seemed to permit that teleological interpretation which required that the Sun should be habitable, accounted tolerably well for certain of the appearances – more especially the appearance of concavity which the spots have when near the limb of the Sun. But though Sir John Herschel supported his father’s hypothesis, pointing out that cyclonic action would account for local dispersions of the photosphere, there has of late years become more and more manifest the fatal objection that the genesis of light and heat remained unexplained, and that no supposition of auroral discharges did more than remove the difficulty a step back; since, unless light and heat could be perpetually generated out of nothing, there must be a store of force perpetually being expended in producing them. A counter-hypothesis, following naturally from the hypothesis of nebular origin, is that the mass of the Sun must be incandescent; that its incandescence has been produced, and is maintained, by progressing aggregation of its once widely-diffused matter; and that surrounding its molten surface there is an atmosphere of metallic gases continually rising, condensing to form the visible photosphere, and thence precipitating. What, in this case, are the solar spots? Kirchhoff, proceeding upon the hypothesis just indicated, which had been set forth before he made his discoveries by the aid of the spectroscope, contended that the solar spots are simply clouds, formed of these condensed metallic gases, so large as to be relatively opaque; and he endeavoured to account for their changing forms as the Sun’s rotation carries them away, in correspondence with this view. But the appearances as known to astronomers, are quite irreconcilable with the belief that the spots are simply drifting clouds. Do these appearances, then, conform to the supposition of M. Faye, that the photosphere encloses matter which is wholly gaseous and non-luminous; and that the spots are produced when occasional up-rushes from the interior burst through the photosphere? This supposition, while it may be held to account for certain traits of the spots, and to be justified by the observed fact that there are up-rushes of gas, presents difficulties not readily disposed of. It does not explain the manifest rotation of many spots; nor, indeed, does it seem really to account for that darkness which constitutes them spots; since a non-luminous gaseous nucleus would be permeable by light from the remoter side of the photosphere, and hence holes through the near side of the photosphere would not look dark. There is, however, another hypothesis which more nearly reconciles the facts. Assuming the incandescent molten surface, the ascending metallic gases, and the formation of a photosphere at that outer limit where the gases condense; accepting the suggestion of Sir John Herschel, so amply supported by evidence, that zones north and south of the Sun’s equator are subject to violent cyclones; this hypothesis is, that if a cyclone occurs within the atmosphere of metallic gases between the molten surface and the photosphere, its vortex will become a region of rarefaction, of refrigeration, and therefore of precipitation. There will be formed in it a dense cloud extending far down towards the body of the Sun, and obstructing the greater part of the light radiating from below. Here we have an adequate cause for the formation of an opaque vaporous mass – a cause which also accounts for the frequently observed vortical motion; for the greater blackness of the central part of the umbra; for the formation of a penumbra by the drawing-in of the adjacent photosphere; for the elongation of the luminous masses forming the photosphere, and the turning of their longer axes towards the centre of the spot; and for the occasional drifting of them over the spot towards its centre. Still, there is the difficulty that vortical motion is by no means always observable; and it remains to be considered whether its non-visibility in many cases is reconcilable with the hypothesis. At present none of the interpretations can be regarded as established. See, then, the rigour of the inquiry. Here are sundry suppositions which the man of science severally tests by observations and necessary inferences. In this, as in other cases, he rejects such as unquestionably disagree with unquestionable truths. Continually excluding untenable hypotheses, he waits to decide among the more tenable ones until further evidence discloses further congruities or incongruities. Checking every statement of fact and every conclusion drawn, he keeps his judgment suspended until no anomaly remains unexplained. Not only is he thus careful to shut out all possible error from ina