Popular Science Monthly/Volume 13/June 1878/The Scientific Study of Human Testimony II

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LIMITATIONS of the Senses.—The senses, which have hitherto been regarded as infallible, are even more narrowly defined than the memory or the higher qualities of intellect. So narrow is the range of vision—and the sight is certainly the best of the five senses—that the retina can appreciate a few only of the rays that come from the sun. The vibrations of ether beyond the red at one end of the spectrum, and the violet at the other are of no value in vision, ethereal undulations higher than seven hundred and ninety trillions a second, or lower than four hundred trillions a second, being powerless to affect it.

Equally striking is the limitation of vision as regards distance and magnitude. Only under the most favorable conditions are heavenly bodies of the sixth and seventh magnitude visible to the naked eye. The extreme limit for small objects, according to the experiments of authorities, is represented by a disk 1500 of an inch in breadth. The aid afforded to the sight by the telescope and microscope is important, and, in scientific research, indispensable; but, as compared with the infinitely great and the infinitely little in Nature, it is trifling.

The senses, indeed, are not formed to enable man to solve the problems of Nature, but, as with the lower animals, merely to make existence possible, and, in a limited and incidental way, agreeable. And yet it is through these feeble senses that all human knowledge enters the brain, since all deductive reasoning must be based on previous inductive observation. More humiliating still, and more instructive in its relations to human testimony, is the lack of precision and power of appreciating details at long distances through the eye. At the interval of half a mile we are unable to recognize the countenance of our dearest friend; while ordinary type, in order to be read, must be held within a few inches of the face.

A recognition of the limitations of the sight—the king of the senses—makes the recognition of the limitation of the inferior faculties of hearing, smelling, tasting, and touching, easy and inevitable. Vibrations of the air below 32 per second, or above 100,000 per second, at the extreme, make no impression on the human ear; and, as experiments in the presence of audiences have proved, sensitive flames may react to atmospheric vibrations in perfect silence. Ordinary conversation is audible only within a few feet, while powerful-voiced orators in their mightiest efforts reach but a few thousands of people. The sense of smell is so restricted in its capacity that it fails to detect many of the most deadly poisons and causes of epidemics, and is of such slight practical service to man that patients who, through disease, have lost it entirely, sometimes say that they would not care to have it restored.

The sense of touch, of which all the other senses are supposed to be modifications, being of necessity limited to actual contact, is of no value in the study of anything at a distance.

It is clear, therefore, that the senses open but a few rooms in the infinite palace of Nature, and of these few they give us but feeble and imperfect glimpses. Throwing all questions of supernaturalism aside, it must be allowed that the senses bring us into direct relation with only an infinitesimal fraction of the natural; we are practically shut out of a knowledge of Nature, of which we are a part; hence the narrow limitations of human knowledge, all of which must be inductively based on what the senses are able to teach us, although the superstructure may by deduction be raised very high. The elementary and all-important facts in Nature are precisely those of which the senses, singly or combined, give us little information, or none whatever. The great forces—light, heat, electricity, gravity—can be studied in their effects only, not in themselves—in what they do rather than in what they are; hence it is that the great and central advances in science—the Copernican theory, the theory of gravitation, the wave-theory of light—are along the line of deductive, not inductive, investigation. If we depended on induction, we should know nothing of Nature, but would be blind babes wandering in a pathless forest. The first step in the evolution of any great science has ever been and must ever be the cutting loose from the rule of the senses, the making them servants instead of kings; the base-line the eye may trace out, but reason must construct the triangle; the arc and chord may be measured by the hand, but only calculation gives us the limits of the circle.

The deceptions of the senses are wellnigh as marked as their limitations; indeed, are a part of their limitations. Reid, the metaphysician, argues elaborately that the so-called deceptions of the senses are rather mistakes of judgment in regard to the impressions made on the nerves of special sense. Such argument is needless, since all the convictions that we acquire through the senses—the truths as well as errors—are the products of judgment. It is not the eye, but the brain behind the eye, that sees. The impressions made on the retina do not of themselves carry thoughts to the mind, any more than the impression on the photographer's plate carries thought to the instrument behind it. The eye is an instrument through which the brain sees—the telescope and microscope of the mind. Of itself the eye is as incompetent to see as is the telescope to discover a new planet, or the microscope to detect a humble organism.

"The eye sees what it brings the means of seeing; "it is the astronomer and microscopist that discover; it is the brain that sees through the doors opened by the eye. Conceptions and misconceptions, obtained through the sense of vision, are alike products of the brain rather than of the seeing apparatus. In scientific strictness our senses neither teach nor deceive us.

Although the eye is, as has been said, the best of the senses, it is yet, in some respects, the worst, as more untruths or half-truths enter the brain through this sense than through all the other senses combined; the very efficiency and value of the vision, its clearness and comprehensiveness, its apparent certainty and grasp of detail, cause us to repose in it with greater confidence, and to yield to its suggestions with fewer questionings. Forgetting the limitations of the optical apparatus, and assuming that its office is not to see but to provide the mechanism of seeing—quite overlooking the obvious facts that we never see the whole of objects but only their surfaces, usually but one or two sides at most; that it is practically impossible to fully fix the attention on two widely-separated objects simultaneously; that form and color and size, which are learned through sight, may be of far less importance in determining the nature of objects than their other qualities—men erroneously judge that what is seen is necessarily the truth and the whole truth. When I look at any object, as a chair, I do not see it, cannot see it, however near it may be, and however good my eyesight or concentrated my attention; I see only the bare surface of the portion that is turned toward me, which is but an infinitesimal fraction of the chair itself; and though I turn it round and round, and look at every side, I can never see it, while only a portion of its surface even can ever be seen at one time. Such is part of the philosophy of the success of jugglery and all the forms of tricks of sleight-of-hand; audiences fancy themselves to be seeing what they do not see. Casting our eyes upward to the sun and moon and stars, these heavenly objects seem to move with measurable slowness across the concave surface of the blue arch of sky; and only through the deductive reasonings and calculations of a Copernicus, a Galileo, a Newton, are we brought to the conviction that the earth is the moving object, that the blue vault but marks in the air the limitations of our vision, and that the shining stars that appear as candles in the sky are gigantic worlds moving with enormous velocity millions of miles away. Sitting in a railway-train at a station, as the train next to us on one side begins to move, we seem ourselves to be in motion, and only by looking on the opposite side and steadily observing some point or object that by previous observation we know to be fixed, can we correct our delusion; but in practical life we are not always able to find a fixed point or object external to ourselves by which we can distinguish the subjective and objective in our retinal impressions. Thus, in all human experience, "truth and lies are faced alike; their port, taste, and proceedings, are the same; we look upon them with the same eyes."[1]

Limitations of the Human Brain in Disease.—But the most serious blunders of the sense of sight, or indeed of the other senses, and indeed of reasoning in general, come from confounding the subjective with the objective. In certain states of the system, which are not rare but very common, and which may be either temporary or permanent, the brain has the power not only of modifying the impressions made by external objects over the retina, but of originating impressions even when there are no external objects corresponding to those impressions, and the individuals may have no way of distinguishing subjective from objective visions, or find it very difficult to do so without outside aid.

Not only is it possible for a single individual to be deceived by mistaking subjective for objective impressions, but, as 1 have proved by repeated experiments, the details of which have already been published, it is possible and easy to cause a large number of individuals, of intelligence and in good health, to see simultaneously the same subjective visions without any of them being able to detect the deception. Such experiences of the simultaneous confounding of the subjective with the objective are not exceptional to the degree that we might suppose; they are frequently occurring, and can be verified without difficulty by those who are trained to the art of experimenting with living human beings. All situations and experiences that excite the emotions of awe, of wonder, or reverence, or fear, or expectation, either singly or in combination, are liable to produce subjective visions that may appear at the same time and in the same form to large numbers of people, not one of whom shall be able, without external aid, to recognize the deception; and when these various emotions, powerfully aroused, do not thus cause impressions to be absolutely originated on the retina, they may, and often do, so modify the impressions made by objects to which the eyes and the attention are directed as to give rise to delusions that are both absolute and absurd, and out of which the subjects, though perfectly sane and sound, and, it may be, also scholarly, and accomplished, and scientific, can never be reasoned.

Delusions from this cause are in part, though not entirely, the origin of the myths, the legends, and the traditions, of what is called history, and are constant and oftentimes fatal elements of error in all historical criticism. The science of history will never attain the precision of which it is capable until the chaff of the subjective is winnowed from the wheat of the objective; until it is recognized as a physiological and pathological fact that the seeing of any object by any number of honest and intelligent people is no necessary evidence of the existence of that object; and, until it is understood that the claims of what is seen by individuals or by multitudes, all concurring in their testimony, are to be determined, if determined at all, only by reasoning deductively from the known circumstances under which the claims were made, and from general principles of science previously established.[2] Yet further, it must be understood that the claims of what individuals or multitudes concurrently see are, far more frequently than has been conceded, out of and beyond the reach of scientific investigation; the statements of what men experience furnishing oftentimes no basis for the study of those statements. These remarks are restricted to the evidences of the sense of sight; but with less force, proportioned to their feebler importance, they apply to evidences derived from other senses. Sounds and smells, taste and touch, can be subjectively created, even in a sane and healthy brain. Bring a watch near to the ear, so that its ticking is distinctly heard, then carry it slowly away; soon a point is reached where it is difficult to tell whether the sound heard is in the ear or in the watch: it is easy, indeed, for the most attentive listener to mistake the subjective for the objective, where any form of sound is expected, or feared, or waited for; the husband's footsteps are plainly heard by the anxious wife when they are miles away, and heard many times, it may be, before they come near; and between the deception and the reality there is no practical distinction.

Medical students, taking lessons in auscultation and percussion, on sounding the chest, often deceive themselves as well as their teachers, by hearing the sounds of their own ears perfectly counterfeiting the sounds they are hoping to hear. Not only whisperings and voices arise in the brain, but sustained conversations, with varied modulations, are consciously carried on between the cerebral cells, and are heard as though they proceeded from a distant room. These phenomena appear

not only in insanity, but in far more frequent and less severe nervous disorders, as in trance, hysteria, and simple nervous exhaustion.

The Involuntary Life.—The unconscious and involuntary character of much of mental action is now so far allowed that it may be assumed as a basis for argument in discussions relating to the brain. Many psychologists and some physiologists agree in this, that many of our thoughts are practically unconscious, and all agree that mental action is largely involuntary. This truth, as applied to the higher phases of activity, has long been noted; in the words of Lynch, "when our views are most earnest, most solemn, and most beautiful, we are often conscious of being in a state rather than of making an effort." Says Goethe: "No productiveness of the highest kind, no remarkable discovery, no great thought which bears fruit, and has its results, is in the power of any one. All men, who closely watch their inner life, become conscious of these high truths, at least as that life develops. The sign of growth in the soul is, that it gradually loses confidence in its volitional reasonings about best and highest things, and reposes trust rather in what it feels to be given." We work best when we are not working. In the lower realms of activity, through various gradations, what we call volition has oftentimes but a subordinate influence; much is done automatically, and in spite of or against our wills. The noisy rabble of passions and emotions throw the captain overboard, and the mind either drifts or sails furiously and recklessly before the storm; the very attempt of the will to assert its power is the signal for mutiny: it is most influential when it lies low, and gently guides the helm.

The involuntary life—or that side of mental activity that is independent of volition constitutes even in health the larger part of life, and in certain states of disease man becomes an absolute automaton. The very effort of attention is liable to destroy the scientific value of our observation of the object to which our attention is directed, since it subtracts and draws off the cerebral force from those faculties that are needed in careful and thorough attention; only when one has reached the stage where he can observe without severe, conscious effort, can he be said to be a good observer. An extreme illustration of automatism is the state of trance, a morbid condition of the brain in which, as I have elsewhere sought to prove, the activity is concentrated in some one faculty or group of faculties, the activity of other portions of the brain being for the time suspended. A person in this state may do the very things he especially wills not to do: what he wishes and tries to do he cannot; the will is no longer the master, but the servant. For a person in this state to attempt to observe, is as useless as for a steam engine to attempt to reason; he is an automaton, a machine, a bundle of reflex actions, like a plant or polypus. He sees, hears, smells, tastes, and feels, whatever may be suggested to his emotions either by individual or by attendant circumstances, and these subjective sensations are to him genuine, objective realities. This state of trance is not infrequent, but is most common and constantly occurring; it is not confined to any one class or sex, but all human beings are subject to it; no degree of intelligence or of culture suffices to insure exemption; it comes often when it is least looked for, and its easiest victims are of all persons most unsuspicious and ignorant of its nature. Trance is entirely a subjective state, external causes acting as excitant only, and, of all the numberless exciting causes none are more influential in the average individual than the witnessing of strange or exceptional events; and as the testimony of those who are even partially entranced in regard to what they have seen, or heard, or experienced, or done, is of no value, and as under the excitement of the emotions produced by the real or supposed occurrences of unusual or marvelous events large numbers of witnesses are liable to be simultaneously and similarly entranced, therefore human testimony becomes practically of the least value in just those crises and situations where evidence both for the purposes of science and law is most needed. The influence of psychical contagion, or the excitation of emotions through involuntary imitation, one person carrying the excitement to another, and so on, through vast audiences, is of special import in relation to human testimony: excitement spreads through a multitude in arithmetical ratio, proportioned to the numbers; a crowd is a multiplier of force, and through the stimulus of sight and sound generates a storm of emotion; out of an insignificant cause each individual in his turn unconsciously adding to the original excitement, just as in the Holtz or Gramme electrical machines each new revolution adds to the force obtained by the first. A large audience may be agitated with laughter or melted into abundant tears by a story which, when told to an individual, causes perhaps but a feeble smile or mildly suffused eyes. Average testimony, therefore, in regard to unprecedented, or marvelous, or wondrous phenomena, as the manifestation of supposed new forces, or strange symptoms of disease, or the raising of the dead, or any unusual appearances in Nature, on the earth, in the air, in the sky—such as would be likely to excite the emotions of awe, of wonder, of reverence, or of fear, in the presence of large assemblages—can have no scientific value; a whole army may be entranced, and may see and hear what is dreaded or expected.

Under conditions that strongly excite the emotions, no force of numbers and no concurrence of testimony can give any value to testimony; a million ciphers are worth no more than a single cipher. The greater the number of eye-witnesses, the greater their liability to be deceived through the influence of mental contagion.[3]

But, aside from trance and allied states—which constitute the culmination of the involuntary life—the value of human testimony is impaired, as all lawyers learn by experience, through the emotions acting upon the reason, slowly, it may be, and unconsciously, so as to produce in time sincere but utterly untrue convictions in regard to facts of observation. The wish is so far the father to the thought that men, and especially women and children, reason themselves into an honest conviction that they have seen, or heard, or experienced, something directly opposite to that which they actually saw, or heard, or experienced, and this conviction becomes so organized in the brain that neither by their own efforts nor by the arguments of others can the deception ever be disclosed to them. How true this is of speculative beliefs all know; it is not so well known that it is true also of facts of observation and personal experience, thus vitiating most of human testimony. The wish secretly usurps the throne of the will, and, unknown to the subject, guides with a silent and resistless energy the course of thought in the brain. Every day our courts are forced to attend to the testimony of witnesses who are sure they are telling the truth in regard to what happened, although really they are telling what they wanted to happen. Even in science microscopists who are not yet full experts oftentimes see what they are looking for, and afterward believe they have seen what at the time they did not even profess to see. Herein is the psychology of gossip, which usually consists of a mountain of untruth, of fear, and hope, and jealousy, and anger, and love, and expectation, with a few grains of fact—the offerings of falsehood being oftentimes as honest as the offerings of truth.

Need of a Reconstruction of the Principles of Evidence.—The acceptance of the above facts and reasonings involves the necessity of reconstruction of the principles of evidence, as thus far taught by all our highest authorities in that department. Disagreeing widely on other and far less important departments, all schools, and languages, and ages—writers on law, on logic, on science—agree in accepting what is called the evidence of the senses, although, as we have seen, the senses of themselves can give us no evidence of anything whatsoever; and in this, likewise, there is passive if not active agreement—that the first qualification of a witness is honesty, and that the concurrence of testimony of large numbers is a solid basis for belief. Sir William Hamilton, with no suspicion of the nature or phenomena of trance as here described, quotes with earnest approval the following statement of Esser:

"When the trustworthiness of a witness or witnesses is unimpeachable, the very circumstance that the object is one in itself unusual and marvelous adds greater weight to the testimony; for this very circumstance would itself induce men of veracity and intelligence to accord a more attentive scrutiny to the fact, and secure from them a more accurate report of their observation."

In this single sentence all the errors of the world in regard to human testimony seem to be condensed—the placing of honesty in the front rank of qualifications, the confounding of general intelligence with special intelligence, the inference that the senses are infallible, and the utter non-recognition of the limitations of the brain and its liability to disturbance in the presence of circumstances that excite the emotions.

Reid, after citing the custom of courts in assuming that the eyes and ears are to be trusted, inquires:

"Can any stronger proof be given that it is the universal judgment of mankind that the evidence of sense is a kind of evidence which we may securely rest upon in the most momentous concerns of mankind—that it is a kind of evidence against which we ought not to admit any reasoning, and therefore that to reason either for or against it is an insult to common-sense?"

More recently still, indeed most recently of all, the anonymous author of "Supernatural Religion," in speaking of the testimony of Paul relating to the resurrection, says that it is not of such a character as would be received in a court of justice, thereby implying that the evidence of courts is evidence of the highest kind, whereas from the scientific point of view it is oftentimes the worst kind of evidence—although practically it may be the best that is possible in the administration of law: the form of swearing, though it may make the dishonest transiently honest, and force truth from unwilling lips, can never compensate for the limitations of the human brain, or correct the errors that enter through the senses, or make an expert out of a non-expert.

Laplace enunciates the formula that the more improbable a statement in which witnesses agree, the greater the probability of its truth—a statement which, in view of our present knowledge of the brain, seems almost satirical; but Abercombie, although a physician, gives full assent to the proposition in these words, which could not have been written by any one who had even a general conception of the philosophy of trance:

"Thus we may have two men whom we know to be so addicted to lying that we would not attach the smallest credit to their single testimony on any subject. If we find these concurring in a statement respecting an event which was highly probable, or very likely to have occurred at the time which they mention, we may still have a suspicion that they are lying, and that they may have happened to concur in the same lie, even although there should be no suspicion of connivance. But, if the statement was in the highest degree improbable, such as that of a man rising from the dead, we may feel it to be impossible that they could accidentally have agreed in such a statement; and, if we are satisfied that there could be no connivance, we may receive a conviction from its very improbability that it may be true."

Again, Abercrombie remarks:

"Whatever probability there is that the eyes of one man may be deceived in any one instance, the probability is as nothing that both his sight and touch should be deceived at once; or that the senses of ten men should be deceived in the same manner, at the same time; . . . if we find numerous witnesses agreeing in the same testimony, all equally informed of the facts, all showing the same characters of credibility, and without the possibility of concert or connivance, the evidence becomes not convincing only, but incontrovertible."

Such are the principles of evidence that are taught in our colleges and schools. It is no marvel that most of human philosophy is one vast petitio principii. Men reason that if a large number of witnesses agree in their testimony, if there is no possibility of deception (thus begging the very question of questions), then such and such inferences must follow. On this treacherous quicksand of uncertainty and positive untruth—average human testimony—the world has built, and continues to build, its lofty temples of philosophy, of faith, of history, and of general literature; no wonder that they so quickly crumble and fall, and that the pathway of humanity is marked by their ruins! Even Germany, which in philosophy and science does the original thinking for all nations, has not yet attempted to reduce human testimony to a science; and nowhere is the need for such study more frequently and seriously impressed than in recent German controversial literature.

In many experiments with large numbers of human beings in one room, and operated on simultaneously by some performance that powerfully excites the emotions of wonder, of awe, of reverence, and of expectation, I have proved that a subjective state can be induced in many, if not the majority or all of them, wherein they concurrently see and experience what has no existence; and, after the performance is over, they frequently and permanently persist in their delusions, although they are opposed to the general experience of mankind and all the deductions of science. Why, indeed, should they not do so? They are taught to believe their eyes; they have seen with their eyes such and such phenomena; they are logically compelled to accept the testimony of their senses, even though they do not wish it to be true. I have made these experiments, not only with the aid of profoundly imposing pretensions, as of raising ghosts and the like, but with quite simple methods and appliances, such as professing to magnetize the room by the battery, or to throw a pretended magnetic fluid on the body, or to rub away pain or disease. Not only are the symptoms of disease frequently and simultaneously relieved in a number of persons in these experiments, but trance, with many of its physical and psychical symptoms, such as convulsive movements, sighing respiration, quickened pulse, with hallucinations of sight, of hearing, and other senses. These results, which are of the highest scientific and practical interest, and in various directions, are in the power of any cerebro-physiologist to obtain who has sufficient experience in making experiments with living human beings. A powerful and imposing physique, positiveness and impressiveness of manner, and a reputation as a performer with those on whom they experiment, are aids to these experiments, but are not essential to them.

  1. A critic of Prof. Tyndall, indignant that the philosopher would not accept the reigning delusions of the day, declared that, when called upon to investigate any object, he would look at it, listen to it, touch it, taste it, and smell it, and then not believe it. The critic was not aware that, instead of censuring Prof. Tyndall, he was really giving one of the highest compliments that can be given to a scientific man.
    This over-estimate of the capacity of the human brain and senses, united with the present chaotic state of the principles of evidence, affects injuriously not philosophy alone but practical life as well. In medicine, for example, it has for ages been the fashion to ignore or deride symptoms of a purely subjective nature, that have no corresponding lesions or morbid appearances that the aided or unaided senses can discover, and for the study of which it is necessary to depend on deductive reasoning and the statements of patients. This is in general the explanation of the fact that many of the most frequent and distressing diseases, such as nervous exhaustion, hypochondriasis, hysteria, hay-fever, and allied nervous affections, although of the highest scientific and practical interest, have, until quite recently, been almost entirely neglected, and the agonizing symptoms connected with them are dismissed as trifling if not imaginary. A broken leg every one can see, and touch, and handle; but an exhausted brain, oftentimes a far more serious matter, is passed by, and even its existence is doubted merely for this, that it is out of reach of the eye and the microscope.
  2. Gibbon's "History of the Decline and Fall of the Roman Empire," for example, contains a vast number of statements and discussions which, scientifically, are of no value, and indeed by no manner of possibility could have any value. Details of expressions and actions, which, when obtained directly from the authors, must have been largely untrue, become, when filtered down the centuries through armies of non-experts, but the counterfeit of human experience—a satire on history. The historical writings of Prescott and of Irving are especially open to this criticism, and should be commended to the young with the suggestion, always, that they are to be considered as fiction; indeed, the best novels are better histories than much of professed history, since they do not attempt the impossible burden of carrying exact details, but merely aim to teach general facts, principles, and events, concerning which a certain degree of truth is sometimes attainable.
    A volume of historical criticism is suggested by the following admission of Carlyle in his "French Revolution:" "Nevertheless, poor Weber saw, or even thought he saw (for scarcely the third part of poor Weber's experiences, in such hysterical days, will stand scrutiny), one of the brigands level his musket at her majesty." Are not all the exciting and critical experiences that make up our histories and biographies hysterical or rather entrancing days? On this topic—the untrustworthiness of which is called history—the following remarks of Saint-Beuve, in his criticism of Guizot, are most pertinent, and, so far forth, are in harmony with the philosophy here announced: "I am one of those who doubt, indeed, whether it is granted to man to comprehend with this amplitude, with this certainty, the causes and the sources of his own history in the past; he has so much to do to comprehend it, even imperfectly, at the present time, and to avoid being deceived about it at every hour!" St. Augustine has made this very ingenious comparison: "Suppose that a syllable in the poem of the 'Iliad' were endowed, for a moment, with a soul and with life: could that syllable, placed as it is, comprehend the meaning and general plan of the poem? At most, it could only comprehend the meaning of the verse in which it was placed, and the meaning of the three or four preceding verses. That syllable, animated for a moment, is man; and you have just told him that he has only to will it, in order to grasp the totality of the things which have occurred on this earth, the majority of which have vanished without leaving monuments or traces of themselves, and the rest of which have left only monuments that are so incomplete and so truncated."
    When our youths are taught, as in the future not far away they must be, that the larger portion of historical and controversial literature is of no worth to those who seek for the truth in matters of history and controversy, the process of education will be much simplified; the area of what has hitherto passed for "sound learning" will be greatly restricted, to the relief of all who prefer realities to delusions, and who are oppressed, as every one must be, by the yearly-increasing burden that rests upon those who mingle in the society of scholars.
  3. For more detailed analyses of this subject, the reader is referred to my monograph on the "Scientific Basis of Delusions."