The true kernel of all knowledge is that reflection which works with the help of intuitive representations; for it goes back to the fountain-head, to the basis of all conceptions. Therefore it generates all really original thoughts, all primary and fundamental views and all inventions, so far as chance had not the largest share in them. The Understanding prevails in this sort of thinking, whilst the Reason is the chief factor in purely abstract reflection. Certain thoughts which wander about for a long time in our heads, belong to this sort of reflection: thoughts which come and go, now clothed in one kind of intuition, now in another, until they at last become clear, fix themselves in conceptions and find words to express them. Some, indeed, never find words to express them, and these are, unfortunately, the best of all: quæ voce meliora sunt, as Apuleius says.
Aristotle, however, went too far in thinking that no reflection is possible without pictures of the imagination. Nevertheless, what he says on this point,[122] οὐδέποτε νοεῖ ἄνευ φαντάσματος ἡ ψυχή (anima sine phantasmate nunquam intelligit),[123] and ὅταν θεωρῇ, ἀνάγκη ἅμα φάντασμά τι θεωρεῖν (qui contemplatur, necesse est, una cum phantasmate contempletur),[124] and again, νοεῖν οὐκ ἔστι ἄνευ φαντάσματος (fieri non potest, ut sine phantasmate quidquam intelligatur),[125]—made a strong impression upon the thinkers of the fifteenth and sixteenth centuries, who therefore frequently and emphatically repeat what he says. Pico della Mirandola,[126] for instance, says: Necesse est, eum, qui ratiocinatur et intelligit, phantasmata speculari;—Melanchthon[127] says: Oportet intelligentem phantasmata speculari;—and Jord. Brunus[128] says, dicit Aristoteles: oportet scire volentem, phantasmata speculari. Pomponatius[129] expresses himself in the same sense.—On the whole, all that can be affirmed is, that every true and primary notion, every genuine philosophic theorem even, must have some sort of intuitive view for its innermost kernel or root. This, though something momentary[130] and single, subsequently imparts life and spirit to the whole analysis, however exhaustive it may be,—just as one drop of the right reagent suffices to tinge a whole solution with the colour of the precipitate which it causes. When an analysis has a kernel of this sort, it is like a bank note issued by a firm which has ready money wherewith to back it; whereas every other analysis proceeding from mere combinations of abstract conceptions, resembles a bank note which is issued by a firm which has nothing but other paper obligations to back it with. All mere rational talk thus renders the result of given conceptions clearer, but does not, strictly speaking, bring anything new to light. It might therefore be left to each individual to do himself, instead of filling whole volumes every day.
§ 29. Principle of Sufficient Reason of Knowing.
But, even in a narrower sense, thinking does not consist in the bare presence of abstract conceptions in our consciousness, but rather in connecting or separating two or more of these conceptions under sundry restrictions and modifications which Logic indicates in the Theory of Judgments. A relation of this sort between conceptions distinctly thought and expressed we call a judgment. Now, with reference to these judgments, the Principle of Sufficient Reason here once more holds good, yet in a widely different form from that which has been explained in the preceding chapter; for here it appears as the Principle of Sufficient Reason of Knowing, principium rationis sufficientis cognoscendi. As such, it asserts that if a judgment is to express knowledge of any kind, it must have a sufficient reason: in virtue of which quality it then receives the predicate true. Thus truth is the reference of a judgment to something different from itself, called its reason or ground, which reason, as we shall presently see, itself admits of a considerable variety of kinds. As, however, this reason is invariably a something upon which the judgment rests, the German term for it, viz., Grund, is not ill chosen. In Latin, and in all languages of Latin origin, the word by which a reason of knowledge is designated, is the same as that used for the faculty of Reason (ratiocinatio): both are called ratio, la ragione, la razon, la raison, the reason. From this it is evident, that attaining knowledge of the reasons of judgments had been recognised as Reason's highest function, its business κατ' ἐξοχήν. Now, these grounds upon which a judgment may rest, may be divided into four different kinds, and the truth obtained by that judgment will correspondingly differ. They are stated in the following paragraph.
§ 30. Logical Truth.
A judgment may have for its reason another judgment; in this case it has logical or formal truth. Whether it has material truth also, remains an open question and depends on whether the judgment on which it rests has material truth, or whether the series of judgments on which it is founded leads to a judgment which has material truth, or not. This founding of a judgment upon another judgment always originates in a comparison between them which takes place either directly, by mere conversion or contraposition, or by adding a third judgment, and then the truth of the judgment we are founding becomes evident through their mutual relation. This operation is the complete syllogism. It is brought about either by the opposition or by the subsumption of conceptions. As the syllogism, which is the founding of one judgment upon another by means of a third, never has to do with anything but judgments; and as judgments are only combinations of conceptions, and conceptions again are the exclusive object of our Reason: syllogizing has been rightly called Reason's special function. The whole syllogistic science, in fact, is nothing but the sum-total of the rules for applying the principle of sufficient reason to the mutual relations of judgments; consequently it is the canon of logical truth.
Judgments, whose truth becomes evident through the four well-known laws of thinking, must likewise be regarded as based upon other judgments; for these four laws are themselves precisely judgments, from which follows the truth of those other judgments. For instance, the judgment: "A triangle is a space enclosed within three lines," has for its last reason the Principle of Identity, that is to say, the thought expressed by that principle. The judgment, "No body is without extension," has for its last reason the Principle of Contradiction. This again, "Every judgment is either true or untrue," has for its last reason the Principle of the Excluded Middle; and finally, "No one can admit anything to be true without knowing why," has for its last reason the Principle of Sufficient Reason of Knowing. In the general employment of our Reason, we do not, it is true, before admitting them to be true, reduce judgments which follow from the four laws of thinking to their last reasons, as premisses; for most men are even ignorant of the very existence of these abstract laws. The dependence of such judgments upon them, as their premisses, is however no more diminished by this, than the dependence of the first judgment upon the second, as its premiss, is diminished by the fact, that it is not at all necessary for the principle, "all bodies incline towards the centre of the earth," to be present in the consciousness of any one who says, "this body will fall if its support is removed." That in Logic, therefore, intrinsic truth should hitherto have been attributed to all judgments founded exclusively on the four laws of thinking: that is to say, that these judgments should have been pronounced directly true, and that this intrinsic logical truth should have been distinguished from extrinsic logical truth, as attributed to all judgments which have another judgment for their reason, I cannot approve. Every truth is the reference of a judgment to something outside of it, and the term intrinsic truth is a contradiction.
§ 31. Empirical Truth.
A judgment may be founded upon a representation of the first class, i.e. a perception by means of the senses, consequently on experience. In this case it has material truth, and moreover, if the judgment is founded immediately on experience, this truth is empirical truth.
When we say, "A judgment has material truth," we mean on the whole, that its conceptions are connected, separated, limited, according to the requirements of the intuitive representations through which it is inferred. To attain knowledge of this, is the direct function of the faculty of judgment, as the mediator between the intuitive and the abstract or discursive faculty of knowing—in other words, between the Understanding and the Reason.