Before I enter more fully into this question, it may be worth while to say a few words on its importance. It is an argument on an extreme case, and, like all such arguments, may to many people appear superfluous. Such cases, however, are the tests by which principles are tried, and by which practical conduct has often to be regulated. The chances that neither you nor I will ever meet with five or six perfectly trustworthy witnesses combining to affirm an utterly incredible story are enormously great, but the case of one or two ordinary witnesses affirming very odd stories constantly arises, and as I showed in my article on " Spiritualism," the case of an affirmation, by three credible witnesses, that a man floated about in the air without any tangible or visible cause actually has arisen. It was asserted by Mr. Home, Dr. Gully, and a contributor to the Cornhill Magazine. Unless we have made up our minds as to the relative cogency of direct affirmation and extreme improbability, it is impossible to deal with such cases in a satisfactory way, and the extreme, the crucial case, is the only one which can give satisfaction on the subject.
The question between us thus resolves itself into the question, What is the ultimate ground of belief? why do people believe anything at all? and how are they to act when they are thrown back upon first principles? To this I answered, in my first article, "The ultimate reason for believing what is true is that experience shows that it is beneficial to do so. In all ordinary cases truth ought to be the sole object of our belief, because an enormously wide experience proves that it is wise and beneficial in the end, and with reference to the happiness of the world at large and to the general course of events, to follow truth under all circumstances, and at the expense of any conceivable amount of present sacrifice and discomfort. In cases, however, where we cannot discover the truth," [I should have added, " and yet are obliged to have an opinion,"] "we must revert to first principles, and believe that branch of the alternative presented to us which, upon the whole, it seems most desirable that we should believe." This is my principle. I will show its application immediately. What is yours? I have read both your articles more than once with great attention, and I cannot see how you solve the difficulty. The nearest approach to a statement of your principles which I can find, is contained in the following passages:—You say (May 10, 1862,) "Nor ought we to reject any sensual facts whatever if supported by good evidence. We want in the case of a very unusual and new phenomenon to get evidence which will exclude the hypotheses of imposture and unconscious self-deception. But if these are excluded, we must not hesitate to trust our senses, or the senses of those whose evidence would, according to the general results of human experience, be considered satisfactory." In your other article you say, "The acceptance of a certain amount of ocular testimony as proof of anything whatever which men can see, is the only course that is in keeping with the general drift of social life. All our inquiries into facts in common life rest on the supposition that if a due amount of evidence is forthcoming we have no choice but to believe."
You must forgive me for saying that these principles appear to me to be mere contrivances for eluding the difficulty which I have, at all events, tried to solve. You seem either to deny, or, at any rate, not to appreciate, the existence of the conflict between antecedent improbability and subsequent evidence. I do not for a moment say that the affirmation of what would commonly be called an impossibility by unimpeachable witnesses goes for nothing. On the contrary, it is an extraordinary fact, but so is the occurrence itself; and the reason why I hesitate to believe the statement is identical with the reason why I hesitate to disbelieve the witnesses. It is highly improbable that credible witnesses should lie. It is highly improbable that a dead body cut into four quarters should join itself together and walk about the house. You seem to say that the constitution of human affairs is such that a number of credible witnesses may always be assigned sufficiently great to make the improbability that they should all lie or be deceived greater than the improbability of any fact to which they are supposed to testify. You seem, in a word, to attribute to the direct assertion of a credible human being some sort of specific virtue; to assert that there is some other reason for believing it than the improbability that credible human beings should lie or be deceived; and to affirm that no other species of improbability, even if it implied a failure of all the established rules for the interpretation of nature, and the prediction of phenomena, can even be put into competition with it. This is the only meaning which I can put upon your statement that "the acceptance of a certain amount of ocular testimony as proof of anything whatever which men can see is the only course that is in keeping with the general drift of social life." I can understand this, and I can see how you come to take such a view. It is, as you say, "the only one that is in keeping with the general drift of social life;" but does the "general drift of social life" supply the rule to be followed in such matters? The sort of improbabilities of which, in social life, people allow themselves to be convinced by explicit testimony, are usually small matters, which deserve rather to be described as odd than as improbable. And it is natural enough that people who are continually in the habit of settling such matters by such an appeal should, in course of time, bring themselves to look upon it as the ultimate test of truth; but this is mere habit and practice: nor is it the habit or practice of the most enlightened part of the community.
Viewing the matter apart from "the general drift of social life," I must ask why you have any better right to say that you can always assign a sufficient number of witnesses to prove the truth of any statement, however strange, than I have to say that I can always imagine a state of facts too strange to be proved by the credit of the witnesses whom you assign. Such a contest would be puerile, and, in the strict sense of the word, insignificant. No man has, in reality, any distinct idea of the effect which is produced by the testimony of a vast number of witnesses. If you do not believe a statement deposed to by three or four respectable witnesses, you must be very oddly constituted if you would believe it upon the credit of seven; nor do I believe that there is any man living who would say, "Fourteen respectable witnesses failed to convince me that a dead man swam over the Straits of Dover with his head under his arm, but now that twenty-four have deposed to it, I am convinced."
There is another objection to your theory which appears to me decisive. How do you deal with the case of conflicting testimony? Suppose that, instead of opposing the express evidence of many eyewitnesses to antecedent improbability, you oppose it to the express evidence of an equal number of equally respectable eye-witnesses. How are you to act then? Ten men affirm upon oath that they were present, and heard a man say certain things on a certain occasion. Ten others swear that they also heard him, and that he did not say what is alleged, but that he did say something entirely different. It appears to me that, by your canon you are obliged to believe both that he did and that he did not say what he is said to have said.
The first series of witnesses prove that he said one thing, the second set prove that he did not say anything of the sort. Now, if either set had said that they saw him cut to pieces, and saw the pieces burnt in the fire, and then saw the ashes unite themselves again into a man, you, you say, would believe them. Why, then, should you not believe that he both spoke and did not speak at the same time? The only reason for not doing so is, that it is unlike all previous experience that contradictions should be true; but it is also unlike all previous experience that the other event should take place. I think, however, that no living creature would think of believing that both sets of witnesses spoke the truth. They would say, it is no doubt very odd, but there must be falsehood or error somewhere. It is less improbable that ten witnesses should lie than that a contradiction should be true. If then you come, after all, to a balance of improbabilities, how can you affirm that the improbability of the story told may not be greater than the improbability of the falsehood or error of the witnesses? But this is opposed to the foundation of your theory, which is, that human assertion deserves credit, apart from the question of the balance of probabilities.
You come, then, to balancing improbabilities, but how do you mean to set about it? How will you find out whether, for instance, it is more likely that two unimpeachable witnesses should join to tell a lie, or that a child a month old wrote Latin verses; that four such witnesses should lie, or that a man hanged for murder should come down from the gallows of himself, and walk into his coffin; that twenty such witnesses should lie, or that two and two, on a given occasion, made five? To ask such questions is like asking how much a pound is a fair price for friendship, or what is the distance from one o'clock to London Bridge.
The truth, I think, is that the force of specific evidence to particular facts is very limited, and that all our notions of its cogency are founded upon the tacit assumption that it is confined within a comparatively narrow range of probability or improbability. As soon as you get beyond this range, you are in reality in an unknown country, and when you affect to be balancing conflicting probabilities, you are really talking about you know not what. No doubt you agree with me that it is highly improbable that an arm-chair should preach a sermon. I agree with you that it is highly improbable that ten honest men should unite to tell a lie, and if the honest men assert that they heard the chair preach, we both agree to take the view which involves the less improbability. How are we to set about finding out which of the two things is least improbable? There may, no doubt, be secrets in heaven and earth, utterly unknown hitherto to all the world, which may produce the phenomenon of a preaching armchair. There may also be causes of an equally recondite character which may produce the phenomenon of a common delusion, or tendency to falsehood, besetting ten trustworthy and honest men at the same moment. "Which is the more likely supposition? If you can tell, I cannot. It appears to me like asking whether it is more probable that an aristocratic government is established in the moon, or a democracy in the planet Mars. The value of human testimony depends upon the assumption that it applies to the ordinary established state of things. Try to prove prodigies and miracles as you prove contracts or crimes, and you take it out of its depth, and apply it to purposes for which it was never intended. A Roman Catholic once asked a lady of my acquaintance what she should think if God Almighty told her that the lamp on the table was an armed man? She replied, "I should think I was going out of my wits." The answer seemed to me perfectly true and conclusive. All our thoughts are bounded by a certain horizon, and founded upon certain tacit assumptions. Carry us beyond this limit, and we are at sea, without rudder or compass. There is, I think, in one of Dr. Livingstone's books, a practical illustration of this, which always struck me as not only instructive, but affecting. A native who had come with Dr. Livingstone from the interior of Africa went with him on board a steamer. As he came to see what a wonderful place he had got into, and how all his former notions were upset, he first lost his spirits, and at last went out of his mind, jumped overboard, and was drowned. The poor man's sensibility deserved a better fate, but his catastrophe sets in a striking light the bewilderment which is not only the natural but the only possible result of a harsh and sudden collision between evidence and probability, between the anticipations derived from the past and immediate present experience.
I am well aware of the argument which writers on your side of the question always put forward upon this subject. You dwell upon great scientific discoveries, and ask whether upon the principles which I advocate a wise man ought not to have discredited every invention of modern times. Are not the results produced by steam engines, electric telegraphs, the use of chloroform, and many other things of the same kind, as great a shock to all antecedent experience as any sensible phenomenon which it is possible to imagine? I answered that question broadly in my former article, and I now repeat the answer. People believe in these astonishing results not upon specific testimony to specific facts, but because they form part of the regular constituted system of life, and because they know that explanations of them are offered to the examination of every one who is able and willing to take the trouble of understanding them. Take for instance the electric telegraph. Why do you or I believe that it is possible to transmit messages across thousands of miles in a moment of time? Certainly not because a number of isolated witnesses testify to particular instances in which such messages were as a fact transmitted; certainly not because we, or, at least, I, could give a detailed explanation of the means employed; but because we read telegraphic news every day in the papers, because we see telegraph offices in all the towns and at every railroad station; because we hear of companies formed for the purpose, and see posts and wires said to be their property running over the country in all directions, and also because we have a general notion of the way in which the thing is done. I fully accept the consequence that, until all this evidence, or a considerable part of it, has collected, ordinary people ought not on my principles to have believed specific assertions by credible witnesses as to the instantaneous transmission of news. Suppose for instance, apart from all explanation whatever, credible witnesses had asserted that they went into a room in London, and that a man sitting there told them that a number of facts were then happening at Constantinople, of the occurrence of which satisfactory evidence afterwards arrived in the due course of post, I should not have believed their statement, just as, at present, I do not believe the statements about Mr. Home flying round the room. As soon as the matter was explained I should immediately believe. I should have acted consistently in this, for I disclaim the notion that either my belief or the belief of any man whatever always squares with the truth, or that there is any means by which it can possibly be made to do so. Form your opinions on what principles you please, and they will always be partly false. The most that you can do is to act upon rules which will fail as seldom, and succeed as often as possible. Now I maintain that the rule that you ought to believe what is asserted by credible eye-witnesses ought to be limited by this condition—so long as that which they assert is conformable to the existing state of the knowledge of the person to whom they address themselves. You deny this, appealing to the case of scientific results, to which I reply, true it is that my rule would sometimes prevent some people from believing new truths, but it would more frequently prevent them from believing falsehoods, and it would moreover delay rather than prevent their belief of new truths, and this delay, so far from being an evil, is, in itself, an advantage; therefore my rule is more advantageous than yours.
That my theory would only delay and not prevent the reception of new truth is obvious on a moment's consideration. To return to the case of the electric telegraph, I disbelieve the man who first tells me of the bare results. I disbelieve an accumulation of testimony, all directed to prove that bare result; but when the matter is taken up at the other end I do not disbelieve. I am told on good authority that there is an invisible and imponderable agent in nature which is called electricity, and this is illustrated by a number of sufficiently familiar facts and experiments. By degrees I am taught to see that currents of electricity may by appropriate means be transmitted instantaneously to remote places, and so, step by step, I am led up to the electric telegraph, and when the matter is so put before me, I believe it as firmly as any one—nay, more firmly and in a more intelligent way than a person who believed in the bare wonder when it was first put before him as a mere naked result asserted to be true by alleged eye-witnesses.
That the theory prevents the reception of one kind of falsehoods, and that not an uncommon or unimportant kind, is self-evident. Therefore the only objection to which it is open is that it delays the reception of a certain number of new truths: but what is this objection worth? Very little; for the new truths so reported must by the hypothesis be mere bare results: as soon as the alleged facts are brought into harmony with others, and have their proper places assigned to them in some general theory which reconciles and explains a great number of familiar facts, the case is altered, and the difficulty of believing removed. What harm was there, then, in not believing the true statements of the eye-witnesses in the meantime? Of course in ordinary cases it is insulting to a man to disbelieve his statements, because most of his statements refer to subjects on which detached human testimony is the appropriate proof. When the question is, What was said or done on such an occasion? was a particular man at such a place at such a time? were there twenty sacks of flour in such a boat, or only fifteen?—human testimony is in its proper place; but when a man begins to talk of matters beyond ordinary experience, he gets to talk of what his hearers, or most of them, do not understand, and he ought to be as little affronted by their refusing to believe him as by their refusing to believe him if he talked a foreign language of which they were ignorant. Hence the disbelief of the new truths neither affronts the witness nor injures the hearer. Then what is the harm of it?
You raise a specific objection to one of my remarks, or rather to one of my illustrations, which I may as well deal with here. I had said, that if a murder were said to have been committed in the room, in which and at the time when Mr. Home was said to have floated in the air, and if the witnesses brought to prove the crime all testified to the miracle, I should be sorry to convict upon their evidence. Upon this you say the criminal "would be very lucky if he had the writer on the jury, for any other jury would be unanimous against him. And rightly so, as it appears to us. For why should not the jury say that they have nothing to do with the fact of Mr. Home's floating? It might have been conjuring. It might have been an ocular delusion. It might have been true, and referable to some physical force not yet analyzed, or it might have been a miracle; but at any rate, it had nothing to do with the murder, and that must be judged of by the usual rules of evidence. It seems to us, that it would clearly be the duty of the judge in summing up to keep the two inquiries wholly distinct, and to direct the jury only to think of the murder."
Murder is, no doubt, a bad illustration, because there are generally collateral facts connected with that crime, which corroborate the testimony. The true illustration would be some transitory offence—the uttering, for instance, of treasonable words, which leaves no trace behind it, except in the memory of the witnesses; and making that change in the illustration, I still adhere to it. Several respectable men say that they heard a man say such and such things. They also say, that at the same time and place something miraculous occurred. Here, everything rests on the credit of the witnesses, and they unite in making an incredible statement as to a collateral fact. You say that makes no difference, because the two inquiries are distinct. This is a very simple way of getting out of the difficulty; but it is much more simple than satisfactory. You say the judge ought to tell the jury that the two inquiries should be kept distinct, because the miracle said to have occurred had no connection with the crime said to have been committed. If all collateral inquiries, tending to test the credibility of witnesses, were excluded from courts of justice, their proceedings would be more simplified than improved. Suppose all the witnesses, who agreed as to the words spoken, differed as to the details of the transaction, would you say that that fact had no connection with their credibility, and that the judge ought to tell the jury to dismiss the collateral contradictions from their minds, because they were not directly connected with the question at issue? Surely it would be very wrong to do so; but why? Because, if two people give different accounts of the same fact, it is impossible that both should be right; therefore, one or both are wrong; therefore, you cannot act upon their bare assertion, to the prejudice of a third person; but how does this differ from the case of a common assertion by both of an impossibility? Is it more impossible that witnesses for an alibi, who contradict each other, should both be right, than that a man without visible cause should float about the room? The contradiction, it is admitted, would shake the credit of the witnesses: why should not the assertion? In what sense is it impossible that a contradiction should be true in which it is not impossible that Mr. Home's miracles should be true?
There is a case in which the very circumstance that I am supposing actually did occur. In 1796, one Crossfield was tried for high treason. He was said to have devised a plan for firing poisoned darts at George III., and one of the witnesses against him was a man named Winter, who said that while they were in a French prison-ship together, Crossfield had frequently confessed the whole story. Winter was asked in cross-examination whether he had not been in the habit of telling an odd story about a hare. He said that being between Axminster and Lyme, he stopped by a wall. "A hare came through my arm; I catched him by the leg and turned him round. It was about twelve o'clock at night; I threw him in over the gate, in among a parcel of dogs, and he remained there that night; and the next day, just as the parson was going to church, the hare got out and the dogs followed it through Lyme; there they catched the hare and it was carried up." He was then pressed as to what he thought of the hare, which passed its time safely amongst the dogs, as the counsel said, "like Daniel in the den of lions." He would not own that he thought the matter supernatural, but said, in answer to Lord Chief Justice Eyre, "They say the place is troubled; now I took it to be an old hare." A witness for the prisoner said that Winter told "a number of foolish stories . . . one was of his catching the devil in the shape of a hare, and such ridiculous nonsense." And the Chief Justice, in summing up, said, "The story was certainly a foolish one, though not absolutely impossible to be true; but he added to it that there was a notion that the place was troubled, which leads to a suspicion that he himself conceived there was something supernatural in the event which he related. This would be a strong mark of a distempered imagination . . . The whole taken together marks so strongly that this man's mind is not perfectly composed, that it must weigh against the credit of his testimony, even though there should be no reason to doubt but that he means to speak the truth. This man has given very material evidence against the prisoner, but it can hardly be thought, having this cloud thrown over it, a sufficient foundation for a verdict in this important cause between the king and the prisoner at the bar." [26 St. Tr. pp. 75. 202-3.] What would the judge—and he was an eminent man in his day—have thought of the evidence of men who soberly declared they had seen ottomans climb on to sofas, tables skip and dance, and human bodies float in mid-air, without any visible cause? He would hardly have agreed with you in thinking the fact that such assertions were made utterly irrelevant to the credit of the persons who made them.
Upon the whole, my objections to your argument may be summed up as follows:—You either assert that human testimony has some cogency of its own, independent of the experienced improbability that it should be untrue, and this is obviously absurd; or else you say that experience shows that the truth of any statement, however strange, is less improbable than that a large number of credible witnesses should say what is not true: and for this experience neither does nor can bear you out. In the first case you are reduced to an absurdity; in the second, to a petitio principii.
My own principle is, that it cannot be asserted that the same evidence ought to lead all those who hear and understand it to draw from it the same inferences, but that those inferences ought to vary according to the different degrees of knowledge which the hearers possess, the circumstances in which they are placed, and the use to which they propose to apply their conclusions. This principle appears to me to be of the highest practical importance, and it is also liable to be misunderstood by those who will not take the pains to consider it with candour and attention. I will therefore try to explain it a little more fully. No doubt truth itself is one and unchangeable. One proposition only, and no more, represents the truth, the whole truth, and nothing but the truth upon every subject to which the human mind can be directed, and it is equally certain that if an inquirer into any given subject could ascertain what that proposition was, he could not do better than believe it. An omniscient mind, embracing in one view all the relations of all the phenomena in the universe, would no doubt believe the exact truth upon all subjects relating to or arising out of them. With human beings placed as we are, under an infinite number of restrictions, the attempt to rise at any given time to more than extremely limited and partial views of things is simply idle. We are born into the world with a vast number of passions and appetites, and long before we are masters of our own faculties we are made aware of the existence of a vast flood of facts all about us, with which we have to deal as well as we can, with a view to objects dimly perceived at first, and probably never understood in a manner perfectly distinct and complete. Such, however, is our nature that we cannot effect any object whatever, or deal with any state of circumstances at all, unless we have some sort of knowledge, some sort of general belief. As far as we can guess, this necessity for acting on principles intellectually apprehended is the special peculiarity of the human race, the great mark by which our actions are distinguished from those of brutes. Hence the aggregate of our beliefs for the time being is the most important part of our equipment for the business of life, a more important part if the matter is fairly considered than all the rest put together; for the belief which you or I entertain at any given moment with reference to any given subject-matter determines our conduct with respect to it, and the aggregate of our beliefs determines the aggregate of our conduct. Hence the formation of beliefs or opinions— for the two mean the same thing—is probably the most important business of human life, inasmuch as it gives the colour to every part of it. As we go along in the world every one of us forms for himself a set of opinions, principally, and in most cases, by habit or by the association of ideas; to a small extent, and in a few cases, by independent thought and inquiry; but in one way or another every man, woman, and child in so far as it is a rational creature and not a mere animal, has a set of opinions by which his or her conduct is regulated. The child thinks its parents are ultimate authorities, the woman may think the same of her husband, and the man of his newspaper; but be the opinions what they may, they are the rudders by which every one steers his course. Resign your whole soul, if you please, to the direction of a guide whom you choose to consider infallible and supreme. It is still your opinion of his infallibility and supremacy by which you are guided. Daily and hourly experience shows us that the happiness, the success, in a word the whole value of our lives, depends on the proportion of truth which our stock of opinions contains, and that opinions are valuable only in so far as they correspond with the subject-matter to which they apply. Hence the admission of a new opinion into our stock in hand is a matter of great practical importance, and it ought not to be done without due and careful consideration.
This fact is perfectly consistent with another fact, which exists alongside of it—namely, the miserable insufficiency of the grounds on which most people are compelled to form their opinions by the nature of the case, and the circumstances under which they are placed. For instance, most people in this country have political opinions. It is much to be doubted whether there are fifty, or even ten living men, who have fully considered all that is known on any one political subject; it is certain that the total amount of existing knowledge on any important political subject bears a small proportion to the amount of matter relevant to the subject, which, by sufficient inquiry, might be known, and it is also certain that the few persons who have exhausted any one subject are prejudiced, crotchety, and one-sided. In fact, human knowledge can never get much beyond conjecture. There is, even in the exact sciences, or at least in the application of them, a certain degree of guess-work. What we call the law of gravitation may be only a branch of some wider formula, which, in due time, will falsify all our calculations, and we neglect this possibility whenever we apply it. In the common affairs of life, in politics, in medicine, in moral inquiries, in everything in short that relates to human interests, the conjectural element is far larger. Certain things are suggested to us by evidence. We think them likely, we retain them in our minds till we get accustomed to them, and look upon them as true; and that is all that we really mean when we speak of believing them.
This sceptical view (if you like to call it so) of our beliefs upon all subjects does not in the least interfere with their practical importance. We are very likely to be wrong when we have taken every possible means in our power to be right. Nobody can ever be secure against mistakes upon any subject, but still it is of great importance that he should try his utmost to be right, for experience shows that notwithstanding all that can be said in depreciation of our means of knowledge, the difference between a man who does his best to be right and one who does not care whether he is right or wrong, is of infinite practical importance in every position of life. "Wisdom exceedeth folly as light exceedeth darkness." Our opinions are very poor things, but we are very poor creatures. They go a very little way, but they make that little difference which lies between our little successes and little failures.
If this is a true account of the nature and importance of belief, it follows that the question whether or not a particular proposition is true or false, ought always to be asked with reference to the peculiar circumstances of the person who is expected to answer the question; the thing in itself no doubt is either true or false simply, the words in which the proposition is clothed either do or do not correspond with the facts to which they are meant to apply; but if a thousand different people have occasion to form an opinion on the question, it appears to me that they will probably find it necessary to form a thousand different opinions, varying according to the reasons which they have for forming an opinion, the evidence submitted to them, their time, opportunity, and natural talents for examining it, and a thousand other matters. In the particular case which I have been discussing, a man who views the whole question of spirits and spirit-rapping merely as a sort of toy on which to display his intellectual skill, might naturally take one view, a scientific inquirer would take another, a court of law might view it in a dozen different lights, according to the precise shape in which the matter was presented to them; a patient who hoped for relief from a disease, a disciple to whom the system was presented as the proof of a new religion, a private person to whom some specific advice was tendered, or some particular advantage proposed, might each call for a different amount of evidence before forming his opinion, and might each draw from the very same evidence a different conclusion. Surely the inference from this is, that the formation of an opinion is a practical matter; and that the weight of evidence, its effect on the mind to which it is addressed, varies according to the person who has to receive it, and the occasion on which it is given.
I am, Sir, your faithful servant,
Cornhill Magazine, October 1863.