CHAPTER XIII. EVIDENCE.
“In consequence of some very wonderful laws, which regulate the successions of our mental phenomena, the science of mind is, in all its most important respects, a science of analysis.” Brown’s Lect., i., 108.
BEFORE leaving the subject of Belief, it will be proper to shew, in a few words, what is included, under the name Evidence. Evidence, is either the same thing with Belief, or it is the antecedent, of which Belief is the consequent.
Belief we have seen to be of two sorts: Belief of events; Belief of propositions.
Of events, believed on our own experience, the evidence of the present is sense; of the past, memory; and in these cases, the evidence and the belief are not two things, but one and the same thing. The lamp, which at this moment lights me, I say that I see burning, and that I believe it burning. These are two names of one and the same state of consciousness. “I remember it was burning at the same hour last night,” and “I believe it was burning at the same hour last night,” are also two expressions for the same thing. In the simple anticipation of the future, from the past, also, the evidence, and the belief, are not two things, but one and the same thing. There is a close and inseparable association of the idea of a like antecedent, with the idea of a like consequent. This has not a single name, like memory; but, like memory, it is both evidence and belief.
The case of testimony is different. The Testimony is one thing, the Belief is another. The name Evidence is given to the testimony. The association of the testimony, with the event testified, is the belief.
Beside the belief of events which are the immediate objects of sense, of memory, and of anticipation (the consequence of sense and memory), and of those which are the immediate objects of testimony; there is a belief of events which are not the immediate objects of any of those operations. The sailor, who is shipwrecked on an unknown coast, sees the prints of a man s foot on the sand. The print of the foot is here called the evidence; the association of the print, as consequent, with a man, as antecedent, is called the belief. In this case, the sensation of one event, the print of a foot on the sand, induces the belief of another event, the existence of a man. The sailor who has seen the mark, reports it to his companions who have not quitted the wreck. Instantly they have the same belief; but it is a remove farther off, and there is an additional link of evidence. The first event to them, is the affirmation of their companion; the second, the existence of the print; the third, that of the man. There is here evidence of evidence; the testimony, evidence of the print; the print, evidence of the man.
The companions of the sailor, having themselves gone on shore, perceive, indeed, no man, but see a large monkey, which leaves prints on the sand verymuch resembling those which had first been perceived by their companion. What is now the state of their minds? Doubt. But doubt is a name; what do we call by that name? A phenomenon of some complexity, but of which the elements are not very difficult to trace. There is, here, a double association with the print of the foot. There is the association of a man, and there is the association of a monkey. First, the print raises the idea of a man, but the instant it does so, it raises also the idea of a monkey. The idea of the monkey, displacing that of the man, hinders the first association from the fixity which makes it belief; and the idea of man, displacing that of monkey, hinders the second association from that fixity which constitutes belief.
When evidence is complex; that is, consists of more than one event; the events may be all on the same side, or not all on the same side; that is, they may all tend to prove the same event; or some of them may tend to prove it, some may have an opposite tendency.
Thus, if after discovering the print on the sand, the sailors had seen near it a stick, which had any appearance of having been fashioned into a club, or a spear, this would have been another event, tending, as well as the print on the sand, to the belief of the presence of men. The evidence would have been complex, but all on one side. The process is easy to trace. There is now a double association with the existence of men. The print of the foot excites that idea, the existence of the club excites that idea. This double excitement gives greater permanence to the idea. By repetition, the two exciting causes coalesce, and, by their united strength, call up the associated idea with greater force.
In the case of the appearance of the monkey, in which one of the events tended to one belief, the other to another, we have just seen that the effect is precisely contrary; to lessen the strength of the association with the existence of a man, and to hinder its becoming belief.
These expositions may be applied with ease to the other cases of complex evidence, which can only consist of a greater or less number of events, either all tending to the belief of the same event, or some tending that way, some another; but all operating in the manner which has just been pointed out. Thus we may complicate the present case still further, by the supposition of additional events. After the appearance of the monkey, the sailors may discover, in the neighbourhood, the vestiges of a recent fire, and of the victuals which had been cooked by it. The association of human beings with these appearances is so strong, that, combined with the association between the print and the same idea, it quite obscures the association between the print and the monkey; and the belief that the place has inhabitants becomes complete. But suppose, further; that after a little observation, they discover an English knife, and fork, and a piece of English earthenware near the same place. The idea of an English ship having touched at the place, is immediately excited, and all the evidence of local inhabitants, derived from the marks of fire and cookery, is immediately destroyed. In other words, a new association, that with an English ship, is created, which completely supersedes the idea, formerly associated, that of inhabitants existing on the spot.
The whole of the events, which go in this manner to form a case of belief, or of doubt, or of disbelief, are called Evidence. And the association, which binds them together into a sort of whole, as antecedent, and connects with them the event to which they apply as consequent, and which constitutes the belief, doubt, or disbelief, very often goes by the names of “judgment,” “judging of the evidence,” “weighing the evidence,” and so on.
In these cases of the belief of Events upon complicated evidence, there is an antecedent and a consequent; the antecedent consisting of all the events which are called evidence, the consequent of the event, or events evidenced; and lastly, there is that close association of the antecedent and the consequent, which we have seen already, in so many instances, constitutes belief.
We have now to consider, what we call evidence in the case of the Belief of Propositions.
There are two cases of the Belief of propositions. There is belief in the case of the single proposition; and there is belief of the conclusion of a syllogism, which is the result of a combination of Propositions.
We have seen what the process of belief in Propositions is. The subject and predicate, two names for the same thing, of which the predicate is either of the same extent with the subject, or of a greater extent, suggests, each of them, its meaning; that is, call up, by association, each of them, its peculiar cluster of ideas. Two clusters of ideas are called up in connexion, and that a peculiar connexion, marked by the copula. To have two clusters of ideas, to know that they are two, and to believe that they are two, this is nothing more than three expressions for the same thing. To know that two clusters are two clusters, and to know that they are either the same, or different, is the same with having them. In this case, then, as in that of the belief of events, in sense and memory, the belief and the evidence are the same thing.
Belief of the conclusion of a syllogism, is preceded by two other beliefs. There is belief of the major proposition; belief of the minor proposition; by the process immediately above explained, in which the evidence and the belief are the same thing. These are the antecedent. There is, thirdly, belief of the conclusion, this is the consequent. The process of this belief has been so recently explained, that I do not think we need to repeat it. In this case, it is sometimes said, that the two premises are the evidence; sometimes it is said, that the ratiocination is the evidence; in the former of these applications of the word evidence, the belief of the concluding pro position of the syllogism is not included; in the last, it is. The ratiocination is the belief of all the three propositions; and, in this acceptation of the word, the evidence and the belief are not considered as two things, but one and the same thing. This, however, is only a difference of naming. About the particulars named, there is no room for dispute. (110)
[110 This chapter on Evidence is supplementary to the chapter on Belief, and is intended to analyse the process of weighing and balancing opposing grounds for believing.
Evidence is either of individual facts (not actually perceived by oneself), or of general truths. The former is the only case to which much attention is paid in the present chapter; which very happily illustrates it, by the case of navigators having to decide on the existence or non-existence of inhabitants in a newly discovered island. The process of balancing the evidence for and against, is depicted in a very lively manner. Let us see whether the mental facts set down in the exposition, are precisely those which take place.
When the sailors have seen prints of a foot, resembling those of a man, the idea is raised of a man making the print. When they afterwards see a monkey, whose feet leave traces almost similar, the idea is also raised of a monkey making the print, and the state of their minds, the author says, is doubt. Of this state he gives the following analysis: “There is here a double association with the print of the foot. There is the association of a man, and there is the association of a monkey. First, the print raises the idea of a man, but the instant it does so, it raises also the idea of a monkey. The idea of the monkey, displacing that of the man, hinders the first association from the fixity which makes it belief; and the idea of man, displacing that of monkey, hinders the second association from that fixity which constitutes belief.”
This passage deserves to be studied; for without having carefully weighed it, we cannot be certain that we are in complete possession of the author’s theory of Belief.
There are two conflicting associations with the print of the foot. The picture of a man making it, cannot co-exist with that of a monkey making it. But the two may alternate with one another. Had the association with a man been the only association, it would, or might (for on this point the author is not explicit) have amounted to belief. But the idea of the monkey and that of the man alternately displacing one another, hinder either association from having the fixity which would make it belief.
This alternation, however, between the two ideas, of a monkey making the footprint and of a man making it, may very well take place without hindering one of the two from being accompanied by belief. Suppose the sailors to obtain conclusive evidence, testimonial or circumstantial, that the prints were made by a monkey. It may happen, nevertheless, that the remarkable resemblance of the foot prints to those of a man, does not cease to force itself upon their notice: in other words, they continue to associate the idea of a man with the footsteps; they are reminded of a man, and of a man making the footsteps, every time they see or think of them. The double association, therefore, may subsist, and the one which does not correspond with the fact may even be the most obtrusive of the two, while yet the other conception may be the one with which the men believe the real facts to have corresponded.
All the rest of the exposition is open to the same criticism. The author accounts very accurately for the presence of all the ideas which the successive appearance of the various articles of evidence arouses in the mind. But he does not shew that the belief, which is ultimately arrived at, is constituted by the expulsion from the mind of one set of these ideas, and the exclusive possession of it by the other set. It is quite possible that neither of the associations may acquire the “fixity” which, according to the apparent meaning of the author, would defeat the other association altogether, and drive away the conception which it suggests; and yet, one of the sup positions may be believed and the other disbelieved, according to the balance of evidence, as estimated by the investigator. Belief, then, which has been already shewn not to require an inseparable association, appears not to require even “fixity”- such fixity as to exclude the idea of the conflicting supposition, as it does exclude the belief.
The problem of Evidence divides itself into two distinguishable enquiries: what effect evidence ought to produce, and what determines the effect that it does produce: how our belief ought to be regulated, and how, in point of fact, it is regulated. The first enquiry that into the nature and probative force of evidence: the discussion of what proves what, and of the precautions needed in admitting one thing as proof of another are the province of Logic, understood in its widest sense: and for its treatment we must refer to treatises on Logic, either inductive or ratiocinative. All that would be in place here, reduces itself to a single principle: In all cases, except the case of what we are directly conscious of (in which case, as the author justly observes, the evidence and the belief are one and the same thing) in all cases, therefore, in which belief is really grounded on evidence, it is grounded, in the ultimate result, on the constancy of the course of nature. Whether the belief be of facts or of laws, and whether of past facts or of those which are present or future, this is the basis on which it rests. Whatever it is that we believe, the justification of the belief must be, that unless it were true, the uniformity of the course of nature would not be maintained. A cause would have occurred, not followed by its invariable effect; an effect would have occurred, not preceded by any of its invariable causes; witnesses would have lied, who have always been known to speak the truth; signs would have proved deceptive, which in human experience have always given true indication. This is obvious, whatever case of belief on evidence we examine. Belief in testimony is grounded on previous experience that testimony is usually conformable to fact: testimony in general (for even this may with truth be affirmed); or the testimony of the particular witness, or the testimony of persons similar to him. Belief that the sun will rise and set to-morrow, or that a stone thrown up into the air will fall back, rests on experience that this has been invariably the case, and reliance that what has hitherto occurred will continue to occur hereafter. Belief in a fact vouched for by circumstantial evidence, rests on experience that such circumstances as are ascertained to exist in the case, never exist unaccompanied by the given fact. What we call evidence, whether complete or incomplete, always consists of facts or events tending to convince us that some ascertained general truths or laws of nature must have proved false, if the conclusion which the evidence points to is not true.
Belief on evidence is therefore always a case of the generalizing process; of the assumption that what we have not directly experienced resembles, or will resemble, our experience. And, properly understood, this assumption is true; for the whole course of nature consists of a concurrence of causes, producing their effects in a uniform manner; but the uniformity which exists is often not that which our first impressions lead us to expect. Mr. Bain has well pointed out, that the generalising propensity, in a mind not disciplined by thought, nor as yet warned by its own failures, far outruns the evidence, or rather, precedes any conscious consideration of evidence; and that what the consideration of evidence has to do when it comes, is not so much to make us generalize, as to limit our spontaneous impulse of generalization, and restrain within just bounds our readiness to believe that the unknown will resemble the known. When Mr. Bain occasionally speaks of this propensity as if it were instinctive, I understand him to mean, that by an original law of our nature, the mere suggestion of an idea, so long as the idea keeps possession of the mind, suffices to give it a command over our active energies. It is to this primitive mental state that the author’s theory of Belief most nearly applies. In a mind which is as yet untutored, either by the teachings of others or by its own mistakes, an idea so strongly excited as for the time to keep out all ideas by which it would itself be excluded, possesses that power over the voluntary activities which is Mr. Bain’s criterion of Belief; and any association that compels the person to have the idea of a certain consequence as following his act. generates, or becomes, a real expectation of that consequence. But these expectations often turning out to have been ill grounded, the unduly prompt suggestion comes to be associated, by repetition, with the shock of disappointed expectation; and the idea of the desired consequent is now raised together with the idea not of its realization, but of its frustration: thus neutralizing the effect of the first association on the belief and on the active impulses. It is in this stage that the mind learns the habit of looking out for, and weighing, evidence. It presently discovers that the expectations which are least often disappointed are those which correspond to the greatest and most varied amount of antecedent experience. It gradually comes to associate the feeling of disappointed expectation with all those promptings to expect, which, being the result of accidental associations, have no, or but little, previous experience conformable to them: and by degrees the expectation only arises when memory represents a considerable amount of such previous experience; and is strong in proportion to the quantity of the experience. At a still later period, as disappointment nevertheless not unfrequently happens notwithstanding a considerable amount of past experience on the side of the expectation, the mind is put upon making distinctions in the kind of past experiences, and finding out what qualities, be sides mere frequency, experience must have, in order not to be followed by disappointment. In other words, it considers the conditions of right inference from experience; and by degrees arrives at principles or rules, more or less accurate, for inductive reasoning. This is substantially the doctrine of the author of the Analysis. It must be conceded to him, that an association, sufficiently strong to exclude all ideas that would exclude itself, produces a kind of mechanical belief; and that the processes by which this belief is corrected, or reduced to rational bounds, all consist in the growth of a counter-association, tending to raise the idea of a disappointment of the first expectation: and as the one or the other prevails in the particular case, the belief, or expectation, exists or does not exist, exactly as if the belief were the same thing with the association. It must also be admitted that the process by which the belief is overcome, takes effect by weakening the association; which can only be effected by raising up another association that conflicts with it. There are two ways in which this counter- association may be generated. One is, by counter-evidence; by contrary experience in the specific case, which, by associating the circumstances of the case with a contrary belief, destroys their association with the original belief. But there is also another mode of weakening, or altogether destroying, the belief, without adducing contrary experience: namely, by merely recognising the insufficiency of the existing experience; by reflecting on other instances in which the same amount and kind of experience have existed, but were not followed by the expected result. In the one mode as in the other, the process of dissolving a belief is identical with that of dissolving an association; and to this extent and it is a very large extent the author’s theory of Belief must be received as true.
I cannot, however, go beyond this, and maintain with the author that Belief is identical with a strong association; on account of the reason already stated, viz. that in many cases indeed in almost all cases in which the evidence has been such as required to be investigated and weighed a final belief is arrived at without any such clinging together of ideas as the author supposes to constitute it; and we remain able to re present to ourselves in imagination, often with perfect facility, both the conflicting suppositions, of which we nevertheless believe one and reject the other. Ed.]