The actions and feelings of human beings in the social state, are, no doubt, entirely governed by psychological and ethological laws: whatever influence any cause exercises upon the social phenomena, it exercises through those laws. Supposing therefore the laws of human actions and feelings to be sufficiently known, there is no extraordinary difficulty in determining from those laws, the nature of the social effects which any given cause tends to produce. But when the question is that of compounding several tendencies together, and computing the aggregate result of many co-existent causes; and especially when, by attempting to predict what will actually occur in a given case, we incur the obligation of estimating and compounding the influences of all the causes which happen to exist in that case, we attempt a task to proceed far in which, surpasses the compass of the human faculties.
If all the resources of science are not sufficient to enable us to calculate, a priori, with complete precision, the mutual action of three bodies gravitating toward one another, it may be judged with what prospect of success we should endeavor to calculate the result of the conflicting tendencies which are acting in a thousand different directions and promoting a thousand different changes at a given instant in a given society; although we might and ought to be able, from the laws of human nature, to distinguish correctly enough the tendencies themselves, so far as they depend on causes accessible to our observation; and to determine the direction which each of them, if acting alone, would impress upon society, as well as, in a general way at least, to pronounce that some of these tendencies are more powerful than others.
But, without dissembling the necessary imperfections of the a priori method when applied to such a subject, neither ought we, on the other hand; to exaggerate them. The same objections which apply to the Method of Deduction in this its most difficult employment, apply to it, as we formerly showed,(276) in its easiest; and would even there have been insuperable, if there had not existed, as was then fully explained, an appropriate remedy. This remedy consists in the process which, under the name of Verification, we have characterized as the third essential constituent part of the Deductive Method; that of collating the conclusions of the ratiocination either with the concrete phenomena themselves, or, when such are obtainable, with their empirical laws. The ground of confidence in any concrete deductive science is not the _a priori_ reasoning itself, but the accordance between its results and those of observation a posteriori. Either of these processes, apart from the other, diminishes in value as the subject increases in complication, and this is in so rapid a ratio as soon to become entirely worthless; but the reliance to be placed in the concurrence of the two sorts of evidence, not only does not diminish in any thing like the same proportion, but is not necessarily much diminished at all. Nothing more results than a disturbance in the order of precedency of the two processes, sometimes amounting to its actual inversion: insomuch that instead of deducing our conclusions by reasoning, and verifying them by observation, we in some cases begin by obtaining them provisionally from specific experience, and afterward connect them with the principles of human nature by a priori reasonings, which reasonings are thus a real Verification.
The only thinker who, with a competent knowledge of scientific methods in
