Among the principles which, by their pretensions to the title of fundamental, have most figured in the schools, is one called the principle of the Cartesians: "whatever is contained in the clear and distinct idea of any thing, may be affirmed of it with all certainty." We have already seen Kant resuscitate this principle, although in other words, equivocally taking it as synonymous with that of contradiction. Upon close examination we shall easily perceive that the formula of the Cartesians, like that of Kant, only expresses the legitimacy of the criterion of evidence. Both may be simplified to this: evidence is a criterion of truth; or, whatever is evident is true. As we shall hereafter use this transformation to distinguish ideas which we consider very confused, we will show the reason of the equality of the two expressions.
217. To say that any thing is contained in the clear and distinct idea of another thing, is the same as to say that there is evidence that a predicate belongs to a subject; the words have, and can have, no other meaning. To be contained in a clear and distinct idea, is equivalent to seeing one thing in another by that intellectual light which we call evidence; therefore, this expression, "whatever is contained in the clear and distinct idea of any thing," is exactly equivalent to this, "whatever is evident."
To say, that any thing may be affirmed of another with all certainty, is the same as to say, "this thing is true, and we may be perfectly certain of it." It is the truth that is affirmed, and the truth only; therefore, this expression, "may be affirmed of it with all certainty," is exactly equivalent to this, "it is true."
Thus the expression of the Cartesians may be transformed into this: "Whatever is evident is true," or its equivalent, "evidence is a sure criterion of truth."
218. "A predicate that is opposed to a subject does not belong to it," is Kant's formula. The opposition here meant is that founded on ideas, when the predicate is necessarily excluded by intrinsic opposition from the idea of the subject. The expression, then, "a predicate that is opposed to a subject," is equivalent to this: "when the predicate is clearly seen excluded from the idea of the subject," which last is in its turn equivalent to this: "the exclusion, or the opposition between the subject and the predicate, is evident."
"Does not belong to it," means the same as, "it is true that it does not belong to it;" and since these formulas have two values, one for affirmative, another for negative cases, if we say the predicate that is opposed to a subject does not belong to it, we may with equal reason say, the predicate contained in the idea of a subject belongs to it; wherefore, Kant's formula exactly coincides with this: "whatever is evident is true."
219. This transformation gives us greater simplicity and generality; simplicity by the very expression, and generality, because affirmative as well as negative cases are included. The words, "whatever is evident," embrace affirmations as well as negations, for the inclusion of a predicate in a subject may be just as evident as their mutual opposition. Thus, we may see one thing contained in the idea of another, just as we may see it excluded from that idea. Under all conceptions the formula, "whatever is evident is true," is preferable; and if we would express it not as a principle, but as a rule to be applied, it may be converted into this: "evidence is a sure criterion of truth."
220. This transformation must not be supposed to be the only object of the preceding analysis; although in these matters clearness and precision should be carried to the highest possible point, we should nevertheless have abstained from these considerations, had we only proposed to make an innovation, and one perhaps of little practical consequence; the same thing is expressed in both formulas, and he who does not understand the first will not understand the second. Our principal object was not, however, to make this innovation, but to show into what a confusion of ideas those fall who inquire whether the principle involving the legitimacy of the criterion of evidence ought, or ought not, to be considered as fundamental, and be preferred to the principle of contradiction, as also to that of Descartes.
221. We begin by establishing a proposition which may seem a most strange paradox, but is far from being so: the principle of evidence is not evident.
Demonstration.—This principle in its simplest form is this: the evident is true. This proposition, we say, is not evident. When is a proposition evident? When we see the predicate in the idea of the subject; and here this does not occur. Evident is the same thing as clearly seen, as offered to the intellect in a most lucid manner. True is the same as conformity of the idea with the object. We now ask, can you, however much you analyze this idea, "seen with clearness," ever find this other, "conformed to the object?" No. This is an immense leap: we pass from subjectiveness to objectiveness; we affirm subjective to be the reflex of objective conditions; we go from the idea to its object, and this transition is the most transcendental, difficult, and obscure problem of philosophy. Let the reader now decide if we had not ground to assert that the proposition, "the principle of evidence is not evident," was not a paradox.
222. What, then, shall we say of this proposition: "Whatever is evident is true?" It is not an axiom, for the predicate is not contained in the idea of the subject; it is not a demonstrable proposition, for all demonstration rests on evident principles, and consists in deducing from them a consequence evidently connected with them; this cannot take place unless we presuppose the legitimacy of evidence, that is to say, that which is the object of the demonstration. At the commencement of the argument, it might be asked, how do you know the principle on which your argument is based? How do you know it to be true? By evidence. But recollect you are proving that whatever is evident is true, and, therefore, you beg the question. The truth of the laws of logic, to which every argument must conform, is known only by evidence; therefore if we do not suppose whatever is evident to be true, we cannot argue at all.
223. We hold then that the principle of evidence can be based on no other principle, and that, consequently, it has the first mark of the fundamental principle. If it fails, all other principles—that of contradiction, known like the others only by evidence, included—fail with it; this is another mark of the fundamental principle. Let us see if it has the third, by aid of which, whoever denies the rest may be refuted.
Rarely does any one deny the principle of contradiction, and admit that of evidence; yet, making this extravagant supposition, this principle alone would be of avail, because the question would be reduced to this: does he admit the principles to be evident? If he does not, his intellect is unlike that of other men; if he does, the argument brought against him is conclusive. You admit that whatever is evident is true; such or such a principle is evident for you, therefore it is true. The premises are evident of themselves; the legitimacy of the consequence is also evident; and he must consequently admit it, since he admits the criterion of evidence to be a general rule.
224. Whence then the singularity we have noticed in this principle? It is neither evident, nor demonstrable; it is necessary to all others, and whoever denies them is refuted by it. Whence, then, such a singularity? It has a very simple cause; it is, that the principle of evidence expresses no objective truth, and therefore is not demonstrable: it is not a simple fact of consciousness, for it expresses the relation of the subject to the object, for which reason it cannot be limited to the purely subjective; it is a proposition known by a reflex act, and it expresses the primary law of all our objective cognitions. These are founded on evidence; this we experience: but when the mind asks why we trust evidence, we can make no other answer than that whatever is evident is true. What is the foundation of this proposition? Ordinarily it has none; we conform to it without ever thinking of it; but if we take the pains to reflect, we find three motives for assenting to it: the first is an irresistible instinct of nature; the second is the destruction of all our cognitions and the impossibility of thought, if we do not admit the legitimacy of the criterion; the third is the perceiving that, admitting this criterion, every thing is co-ordinated in the intellect, that an ideal universe admirably harmonized, takes the place of chaos, and that we feel possessed of the means necessary to reason and to construct a scientific edifice in the real universe, the knowledge of which we have from experience.(22)
CHAPTER XXIII.
THE CRITERION OF CONSCIOUSNESS.