Chapter IX The Illative Sense
My object in the foregoing pages has been, not to form a theory which may account for those phenomena of the intellect of which they treat, viz. those which characterize inference and assent, but to ascertain what is the matter of fact as regards them, that is, when it is that assent is given to propositions which are inferred, and under what circumstances. I have never had the thought of an attempt which would be ambitious in me, and which has failed in the hands of others, if that attempt may not unfairly be called unsuccessful, which, though made by the acutest minds, has not succeeded in convincing opponents. Especially have I found myself unequal to antecedent reasonings in the instance of a matter of fact. There are those, who, arguing à priori, maintain, that, since experience leads by syllogism only to probabilities, certitude is ever a mistake. There are others, who, while they deny this conclusion, grant the à priori principle assumed in the argument, and in consequence are obliged, in order to vindicate the certainty of our knowledge, to have recourse to the hypothesis of intuitions, intellectual forms, and the like, which belong to us by nature, and may be considered to elevate our experience into something more than it is in itself. Earnestly maintaining, as I would, with this latter school of philosophers, the certainty of knowledge, I think it enough to appeal to the common voice of mankind in proof of it. That is to be accounted a normal operation of our nature, which men in general do actually instance. That is a law of our minds, which is exemplified in action on a large scale, whether à priori it ought to be a law or no. Our hoping is a proof that hope, as such, is not an extravagance; and our possession of certitude is a proof that it is not a weakness or an absurdity to be certain. How it comes about that we can be certain is not my business to determine; for me it is sufficient that certitude is felt. This is what the schoolmen, I believe, call treating a subject in facto esse, in contrast with in fieri. Had I attempted the latter, I should have been falling into metaphysics; but my aim is of a practical character, such as that of Butler in his Analogy, with this difference, that he treats of probability, doubt, expedience, and duty, whereas in these pages, without excluding, far from it, the question of duty, I would confine myself to the truth of things, and to the mind’s certitude of that truth.
Certitude is a mental state: certainty is a quality of propositions. Those propositions I call certain, which are such that I am certain of them. Certitude is not a passive impression made upon the mind from without, by argumentative compulsion, but in all concrete questions (nay, even in abstract, for though the reasoning is abstract, the mind which judges of it is concrete) it is an active recognition of propositions as true, such as it is the duty of each individual himself to exercise at the bidding of reason, and, when reason forbids, to withhold. And reason never bids us be certain except on an absolute proof; and such a proof can never be furnished to us by the logic of words, for as certitude is of the mind, so is the act of inference which leads to it. Every one who reasons, is his own centre; and no expedient for attaining a common measure of minds can reverse this truth;—but then the question follows, is there any criterion of the accuracy of an inference, such as may be our warrant that certitude is rightly elicited in favour of the proposition inferred, since our warrant cannot, as I have said, be scientific? I have already said that the sole and final judgment on the validity of an inference in concrete matter is committed to the personal action of the ratiocinative faculty, the perfection or virtue of which I have called the Illative Sense, a use of the word “sense” parallel to our use of it in “good sense,” “common sense,” a “sense of beauty,” &c.;—and I own I do not see any way to go farther than this in answer to the question. However, I can at least explain my meaning more fully; and therefore I will now speak, first of the sanction of the Illative Sense, next of its nature, and then of its range.