Similarly, if, instead of assuming that conscience is simple because it seems simple to ordinary introspection, he had entertained the hypothesis that it is perhaps complex—a consolidated product of multitudinous experiences received, mainly by ancestors and added to by self—he might have arrived at a consistent system of Ethics. That the habitual association of pains with certain things and acts, generation after generation, may produce organic repugnance to such things and acts,[21] might, had it been known to him, have made him suspect that conscience is a product of Evolution. And in that case his conception of it would not have been incongruous with the facts above named, showing that there are widely different degrees of conscience in different races.
[20] See Principles of Psychology, § 399.
[21] See Principles of Psychology, § 189 (note) and § 520.
In brief, as already implied, had Kant, instead of his incongruous beliefs that the celestial bodies have had an evolutionary origin, but that the minds of living beings on them, or at least on one of them, have had a {199} non-evolutionary origin, entertained the belief that both have arisen by Evolution, he would have been saved from the impossibilities of his Metaphysics, and the untenabilities of his Ethics. To the consideration of these last, let us now pass.
Before doing this, however, something must be said concerning abnormal reasoning as compared with normal reasoning.
Knowledge which is of the highest order in respect of certainty, and which we call exact science, is distinguished from other knowledge by its definitely quantitative previsions.[22] It sets out with data, and proceeds by steps which, taken together, enable it to say under what specified conditions a specified relation of phenomena will be found; and to say in what place, or at what time, or in what quantity, or all of them, a certain effect will be witnessed. Given the factors of any arithmetical operation, and there is absolute certainty in the result reached, supposing there are no stumblings: stumblings which always admit of detection and disproof by the method which we shall presently find is pursued. Base and angles having been accurately measured, that sub-division of geometry which is called trigonometry yields with certainty the distance or the height of the object of which the position is sought. The ratio of the arms of a lever having been stated, mechanics tells us what weight at one end will balance an assigned weight at the other. And by the aid of these three exact sciences, the Calculus, Geometry, and Mechanics, Astronomy can predict to the minute, for each separate place on the Earth, when an eclipse will begin and end, and how near it will approach to totality. Knowledge of this order has infinite justifications in the successful guidance of infinitely numerous human actions. The accounts of every trader, the operations of every workshop, the navigation of every vessel, depend for their trustworthiness {200} on these sciences. The method they pursue, therefore, verified in cases which pass all human power to enumerate, is a method not to be transcended in certainty.
[22] See Essay on “Genesis of Science.”
What is this method? Whichever of these sciences we examine, we find the course uniformly pursued to be that of setting out with propositions of which the negations are inconceivable, and advancing by successive dependent propositions, each of which has the like character—that its negation is inconceivable. In a developed consciousness (and of course I exclude minds of which the faculties are unformed) it is impossible to represent things that are equal to the same thing as being themselves unequal; and in a developed consciousness, action and re-action cannot be thought of as other than equal and opposite. In like manner, every because and every therefore, used in a mathematical argument, connotes a proposition of which the terms are absolutely coherent in the mode alleged: the proof being that an attempt to bring together in consciousness the terms of the opposite proposition is futile. And this method of testing, alike the fundamental propositions and all members of the fabrics of propositions raised upon them, is consistently pursued in verifying the conclusion. Inference and observation are compared; and when they agree, it is held inconceivable that the inference is other than true.
In contrast to the method which I have just described, distinguishable as the legitimate a priori method, there is one which may be called—I was about to say, the illegitimate a priori method. But the word is not strong enough; it must be called the inverted a priori method. Instead of setting out with a proposition of which the negation is inconceivable, it sets out with a proposition of which the affirmation is inconceivable, and therefrom proceeds to draw conclusions. It is not consistent, however: it does not continue to do that which it does at first. Having posited an inconceivable proposition to begin with, it does not {201} frame its argument out of a series of inconceivable propositions. All steps after the first are of the kind ordinarily accepted as valid. The successive therefores and becauses have the usual connotations. The peculiarity lies in this, that in every proposition save the first, the reader is expected to admit the logical necessity of an inference drawn, for the reason that the opposite is not thinkable; but he is not supposed to expect a like conformity to logical necessity in the primary proposition. The dictum of a logical consciousness which must be recognized as valid in every subsequent step, must be ignored in the first step. We pass now to an illustration of this method which here concerns us.
The first sentence in Kant’s first chapter runs thus:—“Nothing can possibly be conceived in the world, or even out of it, which can be called good without qualification, except a Good Will.”[23] And then on the next page we come upon the following definition:—