LECTURE XXIII.

ESSAY, THEORY OF JUDGMENT.*

Examination of the Fourth Book of the Essay on the Human Understanding continued. Of knowledge. Its different modes. Omission of inductive knowledge.—Its degrees. False distinction of Locke between knowing and judging.-That Locke's theory of knowledge and of judgment is resolved into that of the perception of a relation of agreement or of disagreement between ideas. Detailed examination of this theory.-That it is applied to abstract judgments and in nowise to primitive judgments, which imply existence.-Analysis of this judgment: I exist. Three objections to the theory of Locke: 1st, impossibility of arriving at real existence, by the abstraction of existence; 2d, that to begin by abstraction is contrary to the true process of the human mind; 3d, that the theory of Locke contains a paralogism.-Analysis of the judgments: I think, This body exists, This body is colored, God exists, &c.-Analysis of the judgments upon which arithmetic and geometry rest.

We have stopped some time at the beginning of the fourth book of the Essay on the Human Understanding: we will now enter farther into it.

The fourth book of the Essay on the Human Understanding treats of knowledge in general, of its different modes, of its different degrees, of its extent, and of its limits, with some applications: this is, properly speaking, logic with a little ontology. The principle of this logic rests on the theory which we have examined, that of the representative idea. We have seen that the condition of all legitimate knowledge, for Locke, is the conformity of the idea to the object; and we have in every way shown this conformity to be a mere chimera. We have then overturned in advance the general theory of knowledge; but we have overturned it in its principle only. It is in some sort a

* On the true theory of judgment, see 1st Series, Vol. 4, Lecture 20, p 370–376, Lecture 21, p. 414, and Lecture 22, p. 464–477.

prejudicial question, an exception which we have raised against this theory; it is necessary now to examine it in itself, independently of the principle of the representative idea, to follow it in the development which is proper to it, and in the consequences which belong to it.

Whether the idea represents or does not represent, in the system of Locke, we always find that the understanding begins with things only by ideas; that ideas are the only objects of the understanding, and consequently the only foundations of knowledge. Now, if all knowledge necessarily rests upon ideas, where there is no idea there can be no knowledge, and wherever there is knowledge, there has necessarily been an idea. But the reciprocal is not true; and wherever there is an idea, it does not follow that there is knowledge. For example, in order that you should have a profound knowledge of God, it is first necessary that you should have some idea of God; but because you have some idea of him, it does not follow that you have a true or sufficient knowledge of him. Thus knowledge is limited by ideas, but it does not go as far as ideas go.

Book IV. Chap. III. § 1. "We can have knowledge no farther than we have ideas." Ibid., § 6. “Our knowledge is narrower than our ideas.”

If knowledge never surpasses the ideas, and sometimes fails of coming up to them, and if all knowledge turns only on ideas, it is clear that knowledge cannot be any thing more than the relation of one idea with another idea, and that the process of the human mind in knowledge is simply the perception of some relation between ideas.

Book IV. Chap. I. § 1. "Since the mind, in all its thoughts and reasonings, hath no other immediate object but its own ideas, which it alone does, or can contemplate, it is evident, that our knowledge is only conversant about them."

§ 2. "Knowledge then seems to me to be nothing but the perception of the connection or agreement, or disagreement and repugnancy of any of our ideas. In this alone it consists,

Where this perception is, there is knowledge: and where it is not, there, though we may fancy, guess, or believe, yet we always come short of knowledge."

Thence follow different modes and different degrees of knowledge in the system of Locke. We simply know whether we perceive a relation of agreement or disagreement between two ideas. Now we can perceive this relation in two ways: either we perceive it immediately, and then knowledge is intuitive, or we do not perceive it immediately, and it is necessary that we should have recourse to another idea or to several other ideas, which we place between the two ideas whose relation cannot be perceived, so that by means of this new idea or of these new ideas we may seize the relation which escapes us. Knowledge in this case is called demonstrative knowledge. Book IV. Chap. II. § 1. Ibid., § 2.

Here Locke makes an excellent remark, which I ought not to omit, and of which it is just to give him the honor. Doubtless we are often compelled to recur to demonstration, to the intermediation of one idea or of several other ideas, in order to perceive the hidden relation of two ideas; but this new idea which we, in some way, interpose between the two others, it is necessary that we should see its relation with both. Now if the perception of

this relation between this idea and the two others was not intuitive, if it were not demonstrative, it would be necessary to have recourse to the intermediation of a new idea. But if between this idea and the anterior ideas the perception of relation were not intuitive, but demonstrative, it would still be necessary to have recourse to a new idea, and so on without end. The perception of the relation between the middle idea and the extreme terms must then be intuitive, and thus it must be in all the degrees of deduction, so that demonstrative evidence is founded on intuitive evidence and constantly supposes it. Book IV. Chap. II. § 7: “Each step must have intuitive evidence.-Now in every step reason makes in demonstrative knowledge, there is an intuitive knowledge of that agreement or disagreement it seeks with the

next intermediate idea, which it uses as a proof: for if it were not so, that yet would need a proof; since without the perception of such agreement or disagreement, there is no knowledge produced. If it be perceived by itself, it is intuitive knowledge: if it cannot be perceived by itself, there is need of some intervening idea, as a common measure to show their agreement or disagreement. By which it is plain, that every step in reasoning that produces knowledge has intuitive certainty; which when the mind perceives, there is no more required, but to remember it, to make the agreement or disagreement of the ideas, concerning which we inquire, visible and certain. So that to make any thing a demonstration, it is necessary to perceive the immediate agreement of the intervening ideas, whereby the agreement or disagreement of the two ideas under examination (whereof the one is always the first, and the other the last in the account) is found. This intuitive perception of the agreement or disagreement of the intermediate ideas, in each step and progression of the demonstration, must also be carried exactly in the mind, and a man must be sure that no part is left out."

This intuition and demonstration are the different modes of knowledge according to Locke. But are there no others? Is there no knowledge which we acquire except by intuition or by demonstration? How do we acquire knowledge of the laws of exterior nature? Take what you please, gravitation, for example. Certainly here is not simple intuition and immediate evidence; for experiments multiplied and combined are necessary for the least law, and still, alone, they would not be sufficient, the least law surpassing the number, whatever it may be, of particular experiments drawn from it. There must then be an intervention of some other operation of the mind besides intuition. Is it demonstration? This is impossible. What in fact is demonstration? It is the perception of a relation between two ideas by means of a third, but on the condition that the third be more general than the other two, in order to embrace them and bind them. To demonstrate is in the last analysis to draw the par

ticular from the general. But what physical law is more general than that of gravitation, and from what is it deduced? The knowledge of gravitation is not deduced from any other knowledge anterior to it and which contains it. How then have we obtained this knowledge which we certainly have, and how in general have we obtained the knowledge of physical laws? A phenomenon having been presented to us with such a character, in such circumstances we have judged that if this phenomenon should present itself anew in analogous circumstances, it would have the same character; that is, we have at first generalized the particular character of this phenomenon: instead of descending from the general to the particular, we have risen from the particular to the general. This general character is what is called law; we have not deduced this law from a more general law or character; we have drawn it from particular experiments, in order to transfer it beyond; there is here neither simple intuition nor demonstration; it is what is called induction.* It is to induction that we owe all our conquests over nature, all our discoveries of the laws of the world. Natural philosophers, for a long time, contented themselves either with immediate observations, which resulted in nothing of importance, or with reasonings which simply gave hypotheses. For a long time induction was merely a natural process of the human mind, of which all men made use in order to acquire the knowledge of which they had need relatively to the exterior world, without accounting for it or without its passing from practice into science. It is especially to Bacon that we owe, not the discovery, but the exposition and greatest use of this process. It is strange that Locke, the compatriot of Bacon, and who belongs to his school, should, in his classification of the modes of knowledge, have suffered to escape the very one which Bacon has rendered most celebrated and placed in the clearest light. It is strange that the whole sensual

* On induction, see Lecture 13 of this Series, and 1st Series, Vol. 4, Lectures 20 and 22.