C. D. Broad

Professor of Philosophy at Trinity in 1923. In 1926 he became Lecturer in Moral Science, and served as Knightbridge Professor of Moral Philosophy from 1935 to 1953. He had Fellowships and honorary degrees in several countries. President of the Society for Psychical Research 1935-6 and 1958-60.

Summing Up the Case for Psychical Research

 - C. D. Broad -

          I HAVE been asked, as one of the very few professional philosophers interested in psychical research, to give the concluding talk in the series entitled Inquiry into the Unknown*. I am to tell you how the evidence for the alleged facts which the previous speakers have brought to your notice impresses me as a philosopher. And I am to say what bearing I think these alleged facts have on the questions which philosophers discuss.

[1] Edited by Theodore Besterman (London: Methuen & Co. Ltd., 1934.)

The first thing that strikes me is the extraordinary indifference of nearly all professional philosophers to the subject of psychical research. I will give some examples. The nature of Time is a topic of great philosophical importance. It is constantly discussed, and yet the philosophers who are most interested in it ignore the alleged facts of precognition and of supernormal knowledge of events in the remote past. Again, many philosophers have written eloquently and acutely about immortality, but hardly any of them has paid the least attention to the alleged communications of the dead through mediums or to their alleged appearances to survivors. A subject which has been treated by nearly all philosophers is the possible range and the inevitable limitations of human knowledge; yet the alleged evidence for telepathy and clairvoyance is never mentioned in these discussions. Lastly, the mutual influence of body and mind is a standard subject of philosophical investigation; yet it is treated without reference to the alleged facts of fire-walking, levitation, movement of objects without contact, and materialization.

You might, perhaps, think that philosophers ignore the whole subject of psychical research in their writings because they have carefully looked into the alleged facts for themselves and have one and all found that there is nothing there but fraud and delusion. If this were so, it would, of course, be highly significant and important. But I can assure you that it is not so. Most philosophers have never taken the trouble even to read the best of the relevant literature, much less to do any investigation for themselves.

Now this indifference on the part of philosophers is quite inexcusable. Natural scientists have their own special subjects of research, which are enough to occupy a lifetime; and they are not to be blamed if they confine themselves to these, provided they do not dogmatize ignorantly about what they have never investigated. But no such excuse is open to philosophers. It is plain from my examples that the alleged facts which they ignore are directly relevant to the very problems which it is their main business to discuss. Quite apart from this, it is the business of a philosopher to make a resolute attempt to see the world steadily and to see it whole. He has not the right, which other scientists have, to ignore certain aspects of it as irrelevant for his particular purpose.

Having passed this sweeping condemnation on my profession, I must in fairness mention four very honourable exceptions. Henry Sidgwick and William James were philosophers of great eminence, and they started the serious study of psychical research in England and in the United States respectively. Their good example has been followed by Professor Henri Bergson in France and Professor Hans Driesch in Germany, who are happily still with us.

I will now say something about the peculiar difficulties of psychical research. There are always three questions to be asked about any story of a supernormal event, and these must never be mixed up with each other. (1) Did the reported event really happen, and is the description of it which the witnesses gave completely accurate? (2) If so, can it be accounted for in terms of the already known laws and properties of matter and of mind? (3) If it really did happen as reported, and if it cannot be accounted for normally, can we suggest any plausible supernormal explanation of it? And can we test our explanation by further observations or experiments?

Now you might think that the first question, at least, ought to be quite easy to answer with complete certainty in many cases. Unfortunately this is not so, for several reasons which I will now explain to you. (1) Apparently supernormal events have, indeed, been reported in all ages and nations. But they have never been common, and, they are perhaps less common among contemporary Europeans and Americans than in less sophisticated societies. It is only in connexion with a few abnormal people, whom we call 'mediums,' that they happen at all frequently. When they happen to ordinary people they do so only very occasionally and under very special conditions. We may compare such events to total eclipses of the sun, or to very rare diseases which few doctors ever get the chance of observing. Such events cannot be produced or reproduced to order. They are very liable to happen when no skilled or trustworthy observers are at hand, and to fail to happen when such observers are present. So we seldom get an opportunity to compare the reports of a large number of observers who have witnessed events of this kind. This makes it difficult to get rid of mistakes due to personal bias and misperception.

(2) Human testimony is extremely unreliable in matters of detail. We are very liable to overlook incidents which are happening under our noses, and to think that we have actually perceived events which we have in fact merely inferred and which really never happened. All successful conjuring depends on this fact, and most of us can be completely taken in by quite simple tricks. The Society for Psychical Research has done some very careful and interesting experiments on this point. These have shown that intelligent people, who know that they are watching a trick and are trying to find out how it is done, will nevertheless misreport what has actually happened to an extent which is almost incredible. Any lapse of time between witnessing an event and making a report about it introduces further chances of mistake, both positive and negative. We forget essential facts which we did perceive, and we insert connecting links which we never did perceive but which we think we remember.

(3) In the case of physical phenomena, such as materialization, movement of objects without contact, etc., professional mediums lay down certain conditions which, they tell us, are absolutely essential to the production of the phenomena. Darkness, or a very dim red light, is commonly demanded. There must be a circle of sympathetic sitters to give 'power.' The sitters must sing or talk continuously in order to produce the right 'vibrations.' And the materializations must not be touched, or serious injury may be done to the medium.

Now we cannot say that these conditions are not necessary, and it is certain that we get no physical phenomena to observe unless they are fulfilled. But it is plain that every one of these conditions is highly favourable to fraud and highly unfavourable to accurate observation.

(4) Very few professional mediums who claim to produce physical phenomena will consent to be investigated under test conditions. Those who do will often demand that a certain friend or relative or protector shall be present at all the sittings. The investigators are then faced with the delicate problem of keeping an eye on the friend while controlling the medium. Truly, the ideal psychical researcher needs to combine the wisdom of the serpent with the apparent harmlessness of the dove. Even under these circumstances many professional mediums have been caught cheating. And, even when this has not happened, it is commonly noticed that the phenomena become less and less impressive as the conditions are tightened up, and that they fade away altogether just as the conditions become fraud-proof. I am, of course, well aware that many spiritualists of high reputation claim to have witnessed the most startling physical phenomena in full white light in home-circles where the suspicion of fraud or collusion is ridiculous. I do not question the good faith of such witnesses, but I do think that it is most unfortunate that those who can perform such wonders with such ease should so seldom be willing to repeat the phenomena under test conditions in the laboratory of the Society for Psychical Research.

We can now pass to our second question: 'Granted that the events really did happen as reported, can they be explained in terms of the already known laws and properties of matter and mind?' Deliberate fraud is, of course, the most obvious explanation of this kind. Speaking from a fairly extensive and intensive study of the subject, I can say without hesitation that it is quite impossible to explain the best of the reported cases of telepathy, clairvoyance, precognition, and mediumistic communication in this way. As regards the reported cases of physical phenomena, such as materialization, levitation, etc., I am much more doubtful. I can sum up my opinion on this part of the subject, for what it is worth, as follows:

(i) There is no doubt that the vast majority of the physical phenomena produced by professional mediums are due to deliberate fraud; and the conditions under which their performances take place make it generally reasonable to suspect fraud even where it cannot be proved. Yet there are a few cases in which the experiments have been done under extremely rigid conditions, by people who were well aware of the pitfalls, and the results have been recorded automatically by photography or some other device. I might mention as instances the investigation of the materializing medium, Eusapia Paladino, described in Vol. xxiii of the Society for Psychical Research Proceedings; and investigations on Rudi Schneider, who claims to move objects without contact, carried out by Mr. Harry Price and described in his book Rudi Schneider (1930). Those of you who have listened to the earlier talks will know that Rudi is now being investigated by the Society for Psychical Research, and will have heard something about him from Lord Charles Hope and Mr. Theodore Besterman. It is fair to state, however, that there is very strong reason to believe that Eusapia Paladino practised deliberate and long-continued fraud at most stages of her career. And, in Mr. Price's later investigations of Rudi Schneider, published in 1933, an incident is reported which casts doubt on the adequacy of the control that was then being used, if not on the honesty of the medium. These facts illustrate admirably the annoying complexity of the whole subject. All this shows how important it is to get rid of the human factor as much as possible in all investigation of physical phenomena. We must aim at getting a continuous photographic record of everything that is being done by every one present throughout the whole period of a sitting. The development of infra-red photography will eventually make this possible. In a recent number of The Times there was an extremely clear photograph taken of a dinner-party in complete darkness by this method. The persons present were quite easily recognizable. The co-operation of skilled experimental physicists would be of immense value to psychical research in devising methods of continuous non-human control and record, which will work in the dark or in a dim red light.[1]

[1] Since this talk was broadcast Mr. Besterman and Mr. Oliver Gatty have succeeded in taking moving pictures in a feeble red light in the séance-room of the Society for Psychical Research. See their letter to Nature (14th April, 1934), cxxxiii, 369.

(ii) I am inclined to make an exception in favour of some of the startling physical phenomena reported in connexion with the medium D. D. Home, in the nineteenth century. Sir William Crookes was a scientist who displayed intelligence and experimental ability of the first order in all his work before and after his investigation of Home. Crookes's account of his researches on Home's mediumship seem to show exactly the same high qualities which characterized all his other scientific work. It is surely unreasonable not to attach very great weight to the remarkable physical phenomena which Crookes claims to have witnessed and recorded in his laboratory under his own conditions in connexion with Home. The attitude of the scientific world to Crookes in this matter was characteristic and contemptible. When it was known that he was to undertake this investigation, his colleagues cried: 'Now that a real scientist is on the track, the fraud will soon be exposed!' When he had completed his investigation, and had felt compelled by the evidence to accept the phenomena, they said: 'Poor old Crookes! He has evidently gone off his head!'

(iii) There seems to be no serious doubt about the fact of fire-walking. It must be taken along with certain well-attested stories of ordeals in the Middle Ages and of the performances of certain Roman Catholic saints. The best collection of such incidents will be found in a book by M. Olivier Leroy called Les Hommes Salamandres (Paris, 1931). It remains to be seen whether such facts, can be accounted for in terms of the normal physical and physiological properties of human flesh. Undoubtedly the first move towards an explanation is to refer, as Professor Seligman does, to the extraordinary influence of mind over body which is illustrated by the production or the cure of blisters by hypnotism or auto-suggestion. Even this kind of explanation is getting very near to the supernormal, and it would have to be stretched to bursting if some quite well-attested stories are true.

(iv) Personally I find it difficult, in view of the evidence, to resist the conviction that certain Roman Catholic saints have been repeatedly levitated. The 'levitation-fan,' if I may venture to use that expression, of the Roman Church is St. Joseph of Copertino, (1603 to 1663). The evidence for his performances is related and discussed in M. Leroy's book Levitation (London, 1928). I do not see how to get over it.

To conclude this part of the subject: As at present advised, I am inclined to think it rather more likely than not that there is a residuum of physical phenomena which are not due to fraud and which cannot be explained in terms of the already known laws and properties of mind and matter. But I do not feel nearly so certain of this as I do about telepathy, clairvoyance, and prevision. I may add that I think that there is adequate evidence for 'hauntings,' in the following sense. Certain rooms and places are centres of 'psychic disturbance.' Over a long period a certain proportion of people who occupy such a room will have supernormal experiences of various kinds, which, in some cases at least, seem to be all connected with a certain event which happened there in the remote past.

We come now to our third question: 'Granted that supernormal powers do exist and that supernormal events do happen, can we suggest any plausible explanation for them?' I will begin with some general remarks, and then go more into detail. (1) The facts are extremely various. There is almost nothing in common between foreseeing a future event and being levitated, except that both are extremely odd and that neither is susceptible of a normal explanation. It is therefore most unreasonable to expect that any one supernormal explanation will cover all the facts. The phenomena need to be classified, and different hypotheses must be put forward to explain prima facie different classes of fact. This does not preclude the possibility that we may, in time, come to see important connexions between classes of phenomena which now seem utterly isolated from each other. E.g. raps and other physical phenomena associated with the death of a person may be a connecting link between purely mental phenomena, such as communications through mediums purporting to come from the dead, and purely physical phenomena, such as movement of objects without contact in presence of a medium.

(2) Any hypothesis which opens up further lines of inquiry, by which it can be tested, is worth consideration; and no hypothesis which is not of this kind is of the least value. Merely to refer all the phenomena to the activities of 'spirits,' human or non-human, seems to me to be a typical example of a perfectly useless type of explanation.

(3) There is a purely logical point which is very important and is often overlooked. In trying to decide between several rival hypotheses in any region of investigation there are always two questions to be considered. (i) Which of them best explains the facts that we are investigating? (ii) Which of them has the greatest antecedent probability, i.e. which of them is most likely in view of what is known or believed about all other facts? The final probability of any hypothesis always depends on both these factors, and the two factors may point in opposite directions. The hypothesis which explains the facts best may have much less antecedent probability than another which does not explain them so well. Now the question of antecedent probability is always a very difficult one. In making judgements about it we are peculiarly liable to be influenced by irrational prejudices of which we are barely conscious. And this difficulty is at a maximum when we are embarking on a wholly uncharted region, as we are in psychical research. We now know so much about the ordinary course of nature that, in explaining any normal phenomenon, all but a few hypotheses can be ruled out as too unlikely to be worth serious consideration. But, once we have passed beyond the normal, we have entered a region in which everything is unfamiliar. Our lack of knowledge prevents us from thinking of more than a few hypotheses, all of which may be quite inadequate. And it prevents us from estimating the relative antecedent probability of the few hypotheses which we can think of. The point about antecedent probability is admirably illustrated by the question of human survival. Some people regard this hypothesis as antecedently so unlikely, in view of the apparent dependence of the human mind on its visible and tangible body, that they would not accept it however well it might explain certain supernormal phenomena. Others, holding different views about the nature of mind and matter, do not find the hypothesis in the least antecedently improbable. This would be the real point at issue, e.g., between Sir Oliver Lodge and certain other psychical researchers who might accept all the supernormal facts which he accepts.

I will now say something in detail about possible explanations of the various kinds of supernormal phenomena. (1) To deal with precognition we shall probably have to revise pretty completely the traditional commonsense view of Time. This need not surprise us. There have always been great, philosophical difficulties about Time. And the work of Einstein has shown that the commonsense view of Time and of Space is quite inadequate even for the purposes of orthodox physics. For interesting suggestions I would refer you to Mr. Dunne's book An Experiment with Time and Mr. Saltmarsh's report on precognition in the Society for Psychical Research Proceedings for February 1934.

(2) To account for telepathy we shall probably have to suppose that the deeper unconscious layers of different minds interpenetrate and affect each other directly. Perhaps it is only the more superficial conscious layers of our minds which are isolated and cannot directly influence each other. Minds might be compared to islands, which are joined in their depths by the bed of the sea, but are separated above.

(3) Clairvoyance, and supernormal knowledge of past states of affairs such as is described in the book called An Adventure, seem to lend support to a theory which Professor Bergson suggested, on quite other grounds, in his Matter and Memory. The theory may be put, very roughly, as follows. The part played by the brain, the nervous system, and the sense-organs in cognition is not, as we commonly think, positive, It is negative and selective. Each mind, if it could exist in a disembodied state, would equally and impartially contemplate everything in space and everything in past time. But in that state active life would be impossible. The function of the organism is to select and concentrate, by shutting off from the mind all that is not relevant at each moment for interacting with the rest of the world at that particular time and place.

Clairvoyance and supernormal knowledge of certain past states of affairs might then be the result of a partial and temporary breakdown of this selective and concentrative function of the organism. I am not, of course, committed to this theory; I am only reminding you that such a theory has been suggested by a very distinguished philosopher, and that these supernormal facts seem to fit in with it.

(4) As regards the physical phenomena, I have no explanation to suggest. It is not profitable to theorize about them until they have been much better established and much more thoroughly observed.

(5) Probably the question which is of most interest to many of you is whether psychical research throws any light on human survival of bodily death. I do not see that most of the physical phenomena have any bearing on this question one way or the other. Telepathy, clairvoyance, precognition, etc., have a certain indirect bearing on it. They suggest that our minds are not so utterly dependent on our visible and tangible bodies as they seem prima facie to be. This makes it less antecedently incredible than it would otherwise be that our minds should go on working when our visible and tangible bodies have broken up. Much the most important direct evidence for survival is the messages which come through mediums in a state of trance. Most of these can be explained quite plausibly by telepathy from the minds of people still alive. But this is certainly not a plausible explanation for all of them.

Of the residue many seem to suggest no more than the temporary persistence of bundles of memory-traces of some kind. This would not constitute survival, in any ordinary sense of the word. There is, however, a small class of mediumistic communications which are most simply and naturally explained by the hypothesis that they are what they claim to be, viz., messages deliberately sent by people who have died, and are still conscious and active. Some of the cross-correspondence cases and some of the book-test cases, which have been elaborately investigated by the Society for Psychical Research, fall into this class. We must add to these certain cases in which it seems as if a person who has died has manifested himself in various ways to various members of his family and friends, in order to console them or for some other specific purpose. Of course the explanation which is the most simple and natural may not be the true one. For reasons which I have tried to state, it is extremely difficult to pass a completely objective judgement on the evidence. My own position at present might be expressed, I think, as follows. As a result of my study of psychical research I shall be slightly more annoyed than surprised if I should find myself surviving the death of my present body.

In conclusion I will say why I think that all these phenomena are of immense interest and importance. It is not because of anything intrinsically great or elevating in them. The physical phenomena are, for the most part, even if genuine, far less spectacular than those which physicists daily witness in their laboratories. Most of the mediumistic communications consist of trivial personal details, or (as it seems to me) second-rate ethico-religious twaddle. Their importance is that they fall outside the well-known and well-established laws and principles of physics and psychology. They thus show that these laws and principles need, at least, to be supplemented and, perhaps, to be radically transformed. In our own lifetime we have seen how a few intrinsically trivial exceptions can lead to a complete transformation of the whole theoretical basis of physics. For the facts which led Einstein to subvert the whole classical theory of gravitation were certain small anomalies in the motion of the planet Mercury, and a certain small bending of light-rays which can be observed only during a total eclipse of the sun and then only with the most delicate instruments. The odd, exceptional, inexplicable facts, however trivial in themselves, are always the points from which the next great and fundamental advance in human knowledge may be made. It is for this reason that I, as a philosopher, attach so much importance to psychical research, and deplore the indifference of most of my colleagues to the subject.

Source: The article above was taken from "Inquiry into the Unknown" edited by Theodore Besterman (London: Methuen & Co. Ltd., 1934) and was originally titled "Summing Up".


More articles by C. D. Broad

Empirical Arguments for Human Survival
The Relevance of Psychical Research to Philosophy

Henry Sidgwick and Psychical Research

Normal Cognition, Clairvoyance, and Telepathy
Human Personality and the Question of its Survival of Bodily Death

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