BOOK IV. usual way, wherein the mind has occasion to employ this faculty, I shall, under these terms, treat of it, as least liable in our language to equivocation. CHAP. XIV. Judgment is the presuming Things to be so, without 4. Thus the mind has two faculties conversant about truth and falsehood :— First, KNOWLEDGE1, whereby it certainly perceives, and is undoubtedly satisfied of the agreement or disagreement 2 perceiving of any ideas. it. Secondly, JUDGMENT, which is the putting ideas together, or separating them from one another in the mind, when their certain agreement or disagreement 2 is not perceived, but presumed to be so; which is, as the word imports, taken to be so before it certainly appears 3. And if it so unites or separates them as in reality things are, it is right judgment 3. 1 'Knowledge' is properly a product, and not a 'faculty' which produces. Locke's knowledge-faculty is what he elsewhere calls intellectual perception-manifested in self-evidence, in demonstration, and in senseperception. 2' agreement or disagreement,' i. c. truth or falsehood. So that in all judgments of probability, risk of error must be faced. Human life turns upon judgments which must be so far intellectual 'leaps in the dark,'-the sunshine of perceived certainty being therein withdrawn from the finite intelligence. CHAPTER XV. OF PROBABILITY. CHAP. XV. ance of ment upon 1. As demonstration is the showing the agreement or dis- BOOK IV. agreement of two ideas, by the intervention of one or more proofs, which have a constant, immutable, and visible Probability connexion one with another; so probability is nothing but the is the appearance of such an agreement or disagreement, by the appear intervention of proofs, whose connexion is not constant and Agreeimmutable, or at least is not perceived to be so, but is, or fallible appears for the most part to be so, and is enough to induce Proofs. the mind to judge the proposition to be true or false, rather. than the contrary. For example: in the demonstration of it a man perceives the certain, immutable connexion there is of equality between the three angles of a triangle, and those intermediate ones which are made use of to show their equality to two right ones; and so, by an intuitive knowledge of the agreement or disagreement of the intermediate ideas in each step of the progress, the whole series is continued with an evidence, which clearly shows the agreement or disagreement of those three angles in equality to two right ones: and thus he has certain knowledge that it is so. But another man, who never took the pains to observe the demonstration, 1 A perceived intellectual necessity is the synthesis of our ideas in knowledge. On the other hand, judgments of probability are states of mind which, by the laws of nature or of spirit, spontaneously follow the presentation of the probable evidence,— the sequence depending in each case on the education, previous experience, and circumstances of the judge. Judg- CHAP. XV. BOOK IV. hearing a mathematician, a man of credit, affirm the three angles of a triangle to be equal to two right ones, assents to it, i. e. receives it for true: in which case the foundation of his assent is the probability of the thing; the proof being such as for the most part carries truth with it: the man on whose testimony he receives it, not being wont to affirm anything contrary to or besides his knowledge, especially in matters of this kind so that that which causes his assent1 to this proposition, that the three angles of a triangle are equal to two right ones, that which makes him take these ideas to agree, without knowing them to do so, is the wonted veracity of the speaker in other cases, or his supposed veracity in this. 2. Our knowledge, as has been shown, being very narrow, supply our and we not happy enough to find certain truth in everything which we have occasion to consider; most of the propositions we think, reason, discourse-nay, act upon, are such as we cannot have undoubted knowledge of their truth: yet some of them border so near upon certainty, that we make no doubt at all about them; but assent to them as firmly, and act, according to that assent, as resolutely as if they were infallibly demonstrated, and that our knowledge of them was perfect and certain 2. But there being degrees herein, from the very neighbourhood of certainty and demonstration, quite It is to Want of Knowledge. 1 'Assent' to what is presumed to be probable is regarded as 'caused,' rather than concluded-as the natural effect of a natural cause; and probabilities lie within the sphere of change, or physical causation, within which unconditional certainty is unattainable by man, or by any other than omniscient intelligence: man is therein made to take ideas to agree without knowing them to do so. 'Whence it proceeds,' says Bishop Butler, that likeness should beget that presumption, opinion, and full conviction, which the human mind is formed to receive from it, and which it does necessarily produce in every one . . . belongs to the subject of logic, and is a part of that subject which has not yet been thoroughly considered. . . . But this does not hinder but that we may be, as we unquestionably are, assured that analogy is of weight towards determining our judgment and our practice. . . . This general way of arguing is evidently natural. For there is no man can make a question, that the sun will rise to-morrow; and be seen, where it is seen at all, in the figure of a circle, and not in that of a square.' (Analogy, Introd.) "This we do, not under the intel lectual necessity of which we are conscious in dealing with abstract conceptions, but, by a spiritual law, which induces faith, in our state of partial intellectual blindness. CHAP. XV. down to improbability and unlikeness, even to the confines of BOOK IV. impossibility; and also degrees of assent from full assurance and confidence, quite down to conjecture, doubt, and distrust: I shall come now, (having, as I think, found out the bounds of human knowledge and certainty1,) in the next place, to consider the several degrees and grounds of probability, and assent or faith 2. which before we know be so. 3. Probability is likeliness to be true, the very notation of Being that the word signifying such a proposition, for which there be makes us arguments or proofs to make it pass, or be received for true. presume Things to The entertainment the mind gives this sort of propositions be true, is called belief, assent, or opinion, which is the admitting or receiving any proposition for true, upon arguments or proofs them to that are found to persuade us to receive it as true, without certain knowledge that it is so. And herein lies the difference between probability and certainty, faith, and knowledge, that in all the parts of knowledge there is intuition; each immediate idea, each step has its visible and certain connexion: in belief, not so. That which makes me believe, is something extraneous to the thing I believe; something not evidently joined on both sides to, and so not manifestly showing the agreement or disagreement of those ideas that are under consideration. Grounds 4. Probability then, being to supply the defect of our The knowledge, and to guide us where that fails, is always of Probaconversant about propositions whereof we have no certainty, bility are but only some inducements to receive them for true. The formity grounds of it are, in short, these two following: two: Con with our own Ex First, The conformity3 of anything with our own knowledge, perience, observation, and experience. or the Testimony Secondly, The testimony of others, vouching their observa- of others. 1 See ch. i-xi. 2 Cf. Introd. § 3. • 'conformity.'- Analogy or likeness to what each man has already had experience of-the custom of his previous experience-is taken as the basis of what appears probable to him. And as in these respects men differ indefinitely, what appears prob- CHAP. XV. BOOK IV. tion and experience1. In the testimony of others, is to be considered: 1. The number. 2. The integrity. 3. The skill of the witnesses. 4. The design of the author, where it is a testimony out of a book cited. 5. The consistency of the parts, and circumstances of the relation. 6. Contrary ence, In this, all the Argu and con testimonies 2. 5. Probability wanting that intuitive evidence which infallibly determines the understanding and produces certain ments pro knowledge, the mind, if it will proceed rationally, ought to examine all the grounds of probability, and see how they ought to be examined, make more or less for or against any proposition, before it assents to or dissents from it; and, upon a due balancing the Judgment. whole, reject or receive it, with a more or less firm assent, proportionably to the preponderancy of the greater grounds of probability on one side or the other 3. For example :— before we come to a If I myself see a man walk on the ice, it is past probability; it is knowledge*. But if another tells me he saw a man in England, in the midst of a sharp winter, walk upon water hardened with cold, this has so great conformity with what is usually observed to happen, that I am disposed by the nature of the thing itself to assent to it; unless some manifest 1 This is called by some 'foreign,' in contrast to personal experiencefounded by the witnesses in like manner on the custom of their experience, and 'conformity' with its analogies. 2 This section suggests the consideration of testimony in its wide meaning, including historical criticism and credibility; also the weight due to the evidence of authority in disputed questions of science, and of philosophical and religious thought. 3 In questions which have to be determined by presumptions of probability, there are reasons on both sides, and objections to every conceivable conclusion. Yet unless we resolve to remain in suspense, which is itself a negative judgment, we are bound in reason to seek for the conclusion that is least open to objection, and most in analogy with our previous experience: this, when recognised, we are naturally induced to assent to. As human life turns upon judgments of probability, this 'balancing' of reasons and objections, in the light of the analogies of personal and foreign experience, is the chief intellectual employment of mankind. The different judgments they are led to form depend upon differences in the history and spiritual experience of the individual judges. 'Seeing' is 'knowing,' according to ch. xi, only when the body that is seen is present. In the supposed instance, the 'man,' so far forth as his visible qualities go, is present; but, as visible qualities alone do not constitute the nominal essence of man, I cannot, on Locke's teaching, know that a man is walking on ice, only by what I see. The sight involves a 'judgment' of probability about absent coexisting qualities in the thing seen. |