Published in 1947 and dedicated to Max Wertheimer it remains a eluding example of the beginnings of Psychology. Here I follow Chapter 1; A Discussion of BehaviorismThere seems to be a single starting point for psychology, exactly as for all the other sciences: the world as we find it, naively and uncritically. The naiveté may be lost as we proceed. Problems may be found which were at first completely hidden from our eyes. For their solution it may be necessary to devise concepts which seem to have little contact with direct primary experience. Nevertheless, the whole development must begin with a naive picture of the world. This origin is necessary because there is no other basis from which a science can arise. In my case, which may be taken as representative of many others, that naive picture consists, at this moment, of a blue lake with dark forests around it, a big, gray rock, hard and cool, which I have chosen as a seat, a paper on which I write, a faint noise of the wind which hardly moves the trees, and a strong odor characteristic of boats and fishing. But there is more in this world: somehow I now behold, thought it does not become fused with the blue lake of the present, another lake of a milder blue, at which I found myself, some years ago, looking from its shore in Illinois. I am perfectly accustomed to beholding thousands of views of this kind which arise when I am alone. And there is still more in this world: for instance, my hand and fingers as they lightly move across the paper. Now, when I stop writing and look around again, there also is a feeling of health and vigor. But in the next moment I feel something like a dark pressure somewhere in my interior which tends to develop into a feeling of being hunted - I have promised to have this manuscript ready within a few months.
Most people live permanently in a world such as this. which is for them the world, and hardly ever find serious problems in its fundamental properties. Crowded streets may take the place of the lake, a cushion in a sedan that of my rock, some serious words of a business transaction may be remembered instead of Lake Michigan, and the dark pressure may have to do with tax-paying instead of bookwriting. All these are minor differences so long as one takes the world at its face-value, as we all do except in hours in which science disturbs our natural attitude. There are problems, of course, even for the most uncritical citizens of this first-hand world. But, for the most part, they do not refer to its nature as such; rather, they are of a practical or an emotional sort, and merely mean that, this world being taken for granted, we do not know how to behave in the part of it which we face as our present situation.
Centuries ago, various sciences, most of all physics and biology, began to destroy the simple confidence with which human beings tend to take this world as the reality. Though hundreds of millions still remain undisturbed, the scientist now finds it full of almost contradictory properties. Fortunately, he has been able to discover behind it another world, the properties of which, quite different from those of the world of naive people, do not seem to be contradictory at all. No wonder therefor that now, as psychology begins to be a science, some of its most energetic students should wish to make it go at once the way of natural science. Indeed, if the scientists have found the naive world impervious to their method, what hope of better success can we as psychologists have? And since the enormous feat of jumping from the world of direct, but confused, experience into a world of clear and hard reality already has been achieved by the physicist, it would seem wise for the psychologist to take advantage of this great event in the history of science, and to begin the study of psychology on the same solid basis.
A few words about the history of scientific criticism will help us better to define the material which psychology is to give up, and to indicate what it is to choose as a more adequate subject matter. Our naive experience consists first of all of objects, their properties and changes, which appear to exist and to happen quite independently of us. So far as they are concerned, it does not seem to matter whether or not we see and feel and hear them. When we are not present or are occupied with other matters, they apparently remain just as they were when we gave them our full attention. Under these circumstances, it was a great step when man began to ask questions about the nature of seeing, feeling and hearing. And it was a revolution when he found that colors, noises and smells, etc., were merely products of influences exerted on him by his surroundings. Still, these surroundings seemed to maintain and support oneself in their primary characteristics and remain "the real world." When those secondary qualities (smell, color,...) were subtracted as purely subjective ingredients, the primary qualities seemed to remain directly given as characteristics of reality. But eventually theprimary qualities of naive realism turned out to be just as subjective as their secondary companions: the form, the weight, and the movement of things had to be given the same interpretation as colors and sounds; they, too, depended upon the experiencing organism and were merely end results of complicated processes in its interior.
What was left? The answer was that, henceforth, no phase of immediate experience could be regarded as part of the real world. Therefore, if both the primary and the secondary characteristics of the experienced world derived from influences which the environment exerts upon the organism, this environment could no longer be identified with man's experienced surrounding. His experienced surroundings were effects of such influences (of the primary and the secondary characteristics of the environment) Hence they could not at the same time be regarded as the causes from which the influences issue. As a result, science had to construct an objective and independent world of physical things, physical space, physical time and physical movement, and had to maintain that this world appears at no point in direct experience.
At this point we must remark that the same reasoning applies to the organism. On the one hand, our body is given to us as a particular thing in sensory experience. On the other hand, this particular sensory experience is directly accessible to us. About the organism, just as about other physical things, we know merely by a process of inference or construction. To the influence of other physical objects my organism responds with processes which establish the sensory world around me. Further processes in the organism give rise to the sensory thing which I call my body. Again others are responsible for the inner side of my experience, for feelings such as hunger and fatigue, for emotions such as fear and hope, and so forth.
We need not consider how the world of science, which does not appear in immediate experience, can nevertheless be investigated by the physicist. There can be no doubt as to the remarkable success of the procedure. Whereas the world of naive man is somewhat confused, and reveals its subjective character in any critical discussion of its properties, in the world of the physicist no confusion and no contradiction are tolerated. Although the rapid changes which physical theory undergoes in our times may surprise us, we still have the feeling that most of these changes are improvements. Eventually, it appears, all important facts of the physical world will be included in a clear and unitary system of knowledge.
Let us now turn to psychology. For a while this discipline was supposed to be the science of direct experience, of its external and internal aspects, as contrasted with physical objects and occurrences. By description of direct experience the psychologist hoped to get not only an orderly survey of all its varieties, but also a great deal of information about the functional relations among these facts. He even aimed at formulating laws which govern the flow of experience.
This conception of psychology has been severely criticized by the psychological school of Behaviorism, which condemns both the subject matter and the purpose of psychology in the older sense. According to the Behaviorist, it has not been possible to give a convincing survey of direct experience; nor has anything come of the attempt to describe the relations among its varieties, or to formulate the laws of so-called "mental life." Obviously, the Behaviorist holds, a science of direct experience which has clear methods and reliable results does not exist. Endless discussions of minor and, less frequently, major items cannot be accepted as a substitute, particularly since facts of experience which are supposed to be the same for all are given utterly different descriptions by different authors. Take the example of images. One psychologist claims to have them in numbers, many of them almost as lively and concrete as percepts. Others tell us that in their direct experience there are no such things, and that the first man is probably deceived by words or other motor phenomena which are related to objects not actually present in experience. If in a simple case like this introspection can give no better result, what shall we expect from it when questions of greater importance but also greater intrinsic difficulty arise? As a matter of fact, the adherents of introspection themselves do not seem to trust their procedure. Apparently they have agreed upon facing important problems as seldom as possible, and to occupy themselves mainly with nuances in the field of sensation which can interest nobody but an Introspectionist. If mere description is to give us a science of direct experience, one naturally expects those who hold this view to attack at once the central facts of their subject matter. And yet they timidly keep to its periphery. In European countries, too, people have long since begun to joke about psychology's ponderous discussion of trifles. It is funny to see how, say in the case of simple comparison as a psychological event, hundreds of pages have been filled with descriptions of minute experiences, while the occurrence and the accuracy of the comparison itself have never been given an explanation. Even in a state of perplexity a science can be highly interesting. But this version of psychology has not only been a complete failure; it also has become a bore to all who do not make it their profession.
The Behaviorist likes to add that the insistence on introspection is closely connected with a philosophical bias. Whether or not we are aware of the fact, in its distinction from the world of physics the concept of direct experience is clearly related to such notions as mind and soul. Surreptitiously the term refers to the activities of a mental substance to which the laws of physics and biology do not apply. As a consequence, a great many superstitions of religious or metaphysical extraction have found it easy to hide within the meaning of the concept. As a child the psychologist has heard a great deal about the soul and its miraculous powers. All this still survives in his statements about direct experience, and makes his introspection a mere defense of medieval darkness.
If this were the only argument against introspection, the Introspectionist might answer against introspection, the Introspectionist might answer that the criticism does not apply to the description of direct experience as such, but merely to a certain danger of which not all Introspectionists may be sufficiently aware. Increased self-criticism and a careful elimination of religious or philosophical interests in students of psychology would have to be recommended as remedies. At the same time such measures would serve as pacifying gestures toward stern Behaviorism.
But the Behaviorist has other reasons for not accepting direct experience as a field of scientific research. First of all, as a procedure, introspection lacks the chief methodological virtue of work in physics: a position of the observer outside the system which he observes. Introspecting and its objects are facts within the same system, and the chances that the former leaves the latter undisturbed are, exceedingly small. Any effort to study sorrow or joy by introspection may serve as an example. If the proper effort is made, such experiences do not remain the same; rather, they tend to disappear, as the selfsame person who has the sorrow or the joy tries to assume the attitude of introspection.
But even if this difficulty could be overcome, according to the Behaviorist we should still find the method useless, because it is so miserably and inevitably subjective. What is the principal characteristic of an objective statement which formulates the result of observations in science? That whoever happens to be interested in the statement can be forced to take it as having a precise meaning. For this purpose we merely have to give the exact definitions of the terms which we are using. For this purpose we merely have to give the exact definitions of the terms which we are using. Thus the atomic weight and the atomic number of an element have clear definitions; thus again the analogy and the homology of morphological structures. There is no physicist or biologist who does not know the exact denotation of these words. But now listen to psychologists who talk, let us say, about the fuzziness which is characteristic of peripheral vision. What exact meaning can be conveyed by this word so long as it has no accurate definition? Such a definition, however, seems to be impossible wherever one has to do with the ultimate data of direct experience. If the psychologist is asked for the definition of fuzziness he may attempt to define it negatively, for instance, as lack of clearness. But this does not help us very much because we must now ask him what he means by clearness. He may now tell us that a high degree of clearness is a normal property of the central part of an orderly visual field. Unfortunately, such a field may have more than one normal property, and in the psychologist's pseudo-definition no differentia specifica is given - in addition to which the word "orderly" needs definition just as badly as do fuzziness and clearness. In any case, the psychologist has now resorted to the only thing which seems feasible where, as in the field of direct experience, a true definition cannot be achieved: he has merely pointed in a certain direction. If one cannot define a term, he may give a hint about the conditions under which the thing in question can be experienced. In case others understand the words by which those conditions are described, they may now attach the undefined term to that phase of their experience to which the term is actually meant to refer. But what a crude and vague procedure this is, if we compare it with the elegant definitions of exact science!
And still we have assumed that, given the same conditions, a person who cannot know more than his own experience will always find it in the same characteristics, objects and occurrences as another person finds in his. Two individual physicists seem to be able to make statements about one and the same event. They seem, for instance, to make readings from one and the same apparatus or scale. But in the case of direct experience two people always have two facts in two separate experiences. What is our evidence for assuming that under given conditions the ultimate data of experience are the same for several persons? Unfortunately, we shall never know whether or not this is the case. On the one hand, color blindness and similar phenomena show conclusively that such an agreement does not generally exist. On the other hand, we have no proof of agreement even in cases in which all imaginable tests give identical results such as precisely the same verbal reports. One person may always report "red" where another person also says "red." Still we know only that the first person has throughout a constant quality wherever and whenever the second person talks about red. We do not know that the first person has the same quality as is called red by the second person. Nor does it help us that what one person calls red seems to have the same exciting character as another person finds in what he calls red. For they may not use the term "exciting" with the same meaning, and actually have different experiences while their expressions are the same.
This is subjectivity in an extreme form. If everyone has his own direct experience, and if he is forever excluded from that of all other persons, direct experience is the private affair of each of us, and with respect to it a common science cannot possibly be achieved. Indeed, since about similar experiences in others so little can be derived from the direct experience of one man, we may go further and ask whether even our best friends have any direct experiences at all. Whatever we see or hear when we talk with them is a part of our experience. What in our experience appears as, say, their voice is first of all the result of physical events in the muscles of their mouths and throats. Such physical events must be understood from the point of view of pure physics and physiology. If so, how do we know that in our friends such processes are accompanied by direct experience?
The Behaviorist might add that he does not deny certain contributions which, before his time, the older forms of psychology have made to the advancement of this science. But he will also say that, when looking upon such achievements from the present point of view, one can easily discover a simple fact: nearly all of them are to the credit not of introspection and description but of objective experimentation. The meaning of this word is just as obvious in psychology as it is in natural science. Instead of inviting a subject to observe and describe his direct experience, we place him in a well-defined situation to which he will react in one way or another. We can observe and measure these responses without his giving us any description of his experiences. In this fashion Weber's law was discovered; this was the kind of experiment by which Fechner made psychology an experimental science; by research of this type, in the almost complete absence of introspection, memory and the formation of habits were investigated; and in the same manner Binet and Simon first measured individual intelligences. At present, even the Introspectionist himself gives us descriptions of colors and tones, pleasures and volition, only so long as he has not found a method in which description is replaced by objective measurement. Again, an individual Introspectionist seems to accept the descriptions of a fellow Introspectionist precisely to the extent to which the other has been able to verify his descriptions by more objective data. What, then, is the use of direct experience and description in any case?
From this criticism the Behaviorists do not all draw quite the same conclusions concerning direct experience as such. Virtually none, it is true, finds direct experience a matter of interest for science, since as the private affair of individuals it is not accessible to objective and therefore scientific observation by others. Only a few members of the school seem to go so far as to deny the existence of direct experience altogether. These particular people obviously hate the very concept. But such minor differences of opinion are of no particular importance. For, as to the question of method, all Behaviorists hold the same negative and positive opinions. In this respect their program is a simple consequence of the foregoing argument. With his objective experimentation the psychologist has tacitly placed himself on strictly scientific ground. His only weakness is that he has not yet become fully aware of the difference in principle between exact techniques and merely subjective groping. Physicists and chemists are interested in knowing how a system which they are investigating will react when exposed to certain conditions; they also ask how the reaction changes when these conditions are varied. Both questions are answered by objective observation and measurement. Now, precisely this is also the adequate form of research in psychology: a subject of a certain type (child, adult, man, woman, or animal) is chosen as the system to be investigated. Certain conditions, among which the most important are those of outside stimulation, are given and objectively controlled. And the resulting reaction of the subject is registered or measured just as are the reactions of systems in physics and chemsitry.
Thus the only thing which psychologists must now recognize is the fact that this procedure alone can serve any serious purpose in their field. Behavior, i.e., the reaction of living systems to environmental factors, is the only subject matter which can be investigated in scientific psychology; and behavior in no way involves direct experience. The experimental work of the future will study even the highest forms of behavior in purely objective terms. This must be so since direct experience does not occur at a single point of an actual experiment. For some, this truth is somewhat obscured by the fact that in many experiments language reactions seem to be of some importance. If the experimenter himself enjoys what he calls direct experience, and if this experience includes a great many things which are associated with words, he will be inclined to take the words of his subject as signs of similar experiences on the part of this person. Nevertheless, such words must be regarded as responses of the subject; and as such they are purely objective physical facts, produced by certain processes in the larynx and the mouth of the subject. Thought the experimenter knows that other objective processes such as those of innervation occur before certain muscles produce words as trains of sound waves, he will be wise if he does not go any further. According to our analysis, he will never know whether any direct experience accompanies those processes. Perhaps we should discipline ourselves to a less frequent use of language reactions in psychological experimentation, until eventually the danger of associating language with direct experience is overcome, and introspection has disappeared from psychology as a science.
Of course, not all reactions of a subject can be objectively observed with the same facility. Sometimes even strong stimulation will not produce overt behavior which we can register with present methods on the outside. In the majority of these cases, however, highly valuable information may be obtained from physiologists, who have studied the functions of the autonomic part of the nervous system and subsequent reactions in the most important visceral organs, including the endocrine glands. One of the main tasks of psychology will be to develop and to adopt available techniques until such visceral reactions can be registered with perfect ease. We also have evidence for assuming that what the Introspectionist calls "thinking" actually consists in slight innervations which the muscles concerned with verbal reactions undergo at the time.
So far, I hope, I have given a fair statement of the opinions which prevail among Behaviorists. It ought to be the more correct since at several points I sympathize with these opinions and am not very fond of introspection as here criticized. Much of current introspection seems to be rather sterile. In an odd contrast to its ambitions, it deflects research from more urgent problems. We will discuss later whether this is an intrinsic property of introspection or merely a consequence of errors which are particularly frequent among Introspectionists.
At present, we have a simpler problem before us. In the natural sciences, the Behaviorist tells us, methods deal with objective reality, whereas the introspection of direct experience - if there is such a thing - deals with something entirely subjective. Is this true? Is this the real reason why natural science has won the admiration of the world while psychology is still in an embryonic state? I cannot admit it. It seems to me that, starting with an admirable enthusiasm for exactness, Behaviorism has been completely misled at this point, and that, as a consequence, the energy spent in objecting to any use of direct experience has been spent in the wrong direction. For, whatever may have happened during the individual development of our keen Behaviorists, about myself I must give the following report, which brings us back to our starting point.
As a child, I had direct experience before I even dreamed of a world entirely beyond it, such as that of physics. At the time I did not, of course, know the term "direct experience." Nor could it have any meaning until I learned about the world of physics with which it then became contrasted. In my original world, innumerable varieties of experience appeared as altogether objective, i.e., as existing or occurring independently and externally. Other experiences belonged to me personally and privately, and were in so far subjective, and a warm, overwhelming happiness at Christmas.
In the next chapters we shall be occupied mainly with objective experience. This term, however, may easily be misunderstood. I shall therefore try to specify its meaning more precisely. In doing so, I shall even run the risk of repeating certain arguments, because this is the point where most of our difficulties arise.
The name "experience" seems to indicate that though appearing as objective, the things around me were actually felt to be given "in my perception." In this sense they would still have remained subjective. But this was not at all the case. They simply were there outside. I had no suspicion whatever of their being merely the effects of something else upon me. I must go further. There was not even a question of their depending upon my presence, upon keeping my eyes open, and so forth. So absolutely objective were those things that for a more objective world no place was left. Even now, their objectivity is so strong and natural that I find myself constantly tempted to attribute to their interior certain characteristics which, according to the physicists, are facts of the physical world. When, in these pages, I use the term "objective experience" it will always have this meaning. For instance, a chair as an objective experience will be something there outside, hard, stable and heavy. Under no circumstances will it be something merely perceived, or in any sense a subjective phenomenon.
In some cases, it is true, the discrimination between the objective and subjective sides of direct experience may become dubious, as with after-images or with the prick of a needle in my finger. This does not make the discrimination less important. To compare with an example from natural science: in physics the discrimination between conducting substances and insulators remains of high value even though between the extremes we find a great many intermediate cases. In our present connection, the main point is the fact that in things, their movements, and so forth, the very highest objectivity is reached.
To repeat, when I first began to study physics I did not learn only about the physical world. Another lesson was necessarily connected with that study: I was introduced to a manner of thinking in which the term direct experience acquired its meaning. The physical world could not be identical with the objective world which I had had around me the whole time. Rather, I learned that physical objects influence a particularly interesting physcial system, my organism, and that my objective experience results when, as a consequence, certain complicated processes have happened in this system. Obviously, I realized, I cannot identify the final products, the things and events of my experience, with the physical objects from which the influences come. If a wound is not the gun which emitted the projectile, then the things which I have before me, which I see and feel, cannot be identical with the corresponding physical objects. These objects merely establish certain alterations within my physical organism, and the final products of these alterations are the things which I behold in my visual field, or which I feel with my fingers.[footnote: We have seen that the same warning applies to the relation between my organism as a physical system and my body as a perceptual fact. My body is the outcome of certain processes in my physical organism, processes which start in the eyes, muscles, skin and so forth, exactly as the chair before me is the final product of other processes in the same physical organism. If the chair is seen "before me," the "me" of this phrase means my body as an experience, of course, not my organism as an object of the physical world. Even psychologists do not always seem to be entirely clear about this point.]
It remains nevertheless true that things in the latter sense were the first objects of which I knew. Moreover, I now understood that any other objects such as those of physics I could never know directly. Plainly, the characteristics of the physical world could be investigated only in a process of inference or construction, however necessary the construction might be. It was in contrast to this, the constructed, world that the world before me could now be called the world of direct experience.
But how can I say that a chair, for example, is an objective experience, If I must admit that it depends upon certain processes in my organism? Does not the chair become subjective on this ground? It does and it does not. At this very moment we have changed the meaning of the terms "subjective" and "objective". In a preceding paragraph "objective: denoted a characteristic which some parts of my experience, in contrast to others, possess as such (exactly as they have size, color, hardness, and so forth. But as the term "subjective" has been used just now it refers to the genetic dependence of all experience upon my physical organism. In this latter meaning, subjectivity is not itself an experienced attribute; rather, it is a relationship which we ascribe to all and therefore also to objective, experiences once we have learned to regard them as results of organic processes. Quite often the two denotations of the term are confused n the most deplorable manner, as thought what is genetically subjective ought also to appear as subjective in experience. Some Introspectionists, for instance, seem to think that, properly speaking, the chair before me must be a subjective phenomenon, which appears before me only as a consequence of learning or interpretation. On the other hand, since no such subjective chair can be discovered, the Behaviorist derides the Introspectionist for dwelling in a world of imaginary ghosts. the simple truth is that some of the experiences which depend upon processes in my organism have the character of objectivity, whereas others which depend upon different processes in the same organism have the character of being subjective. This contrast has nothing to do with the genetic subjectivity of both types of experience, i.e., with the fact that both depend upon understandings of the term "objective experience" will no longer be possible. When I talk about a chair, I mean the chair of my everyday life and not some subjective phenomenon.
On the other hand, we have seen, the chair of objective experience cannot be identified with the chair as part of the physicist's world. Now, since the world of direct experience is the first I knew, and since all I now know about the physical world was later inferred from certain events in the experienced world, how can I be expected to ignore the experienced world? After all, it still remains my only basis for any guesses about physical facts. If I choose, I can, of course, raise the question whether, in a certain sense, the physical world is perhaps the more important one. But even then I must admit that, from the point of view of acquaintance or access, the experienced world is prior to that of physics; also, that my only way of investigating physical realities is that of observing objective experiences and drawing from them the proper conclusions. To be sure, as physiology advances, I may become able to discover the nervous processes which underlie my observing and concluding, and thus to give a physical theory of these events. But again, since the world of physiology is part of the physical world, it can never become directly accessible to me. Any progress which I can make in physiology depends upon my observations of what I call a body in direct perceptual experience. If we listen to Behaviorists we may have the impression that to them the physical and physiological worlds such are directly known, and that in their, the Behaviorists', case knowing has nothing to do with direct experience. None the less, I cannot change this report about my own case in which there is no direct access to physical and physiological facts. Naturally, with this defect I find it frightfully difficult to become a behaviorist.
What, then, about the Behaviorist's statement that, in physics, observation deals with objective reality, whereas, in the case of direct experience, it deals with something that has no scientific value?
Let me describe my own procedure when I investigate the properties of a physical or chemical object. In this mixture of chemical substances, is there any considerable amount of H4C202? I know about the presence of the mixture by way of certain objective experiences before me, and I find the positive answer to the question by smelling, i.e., in a further direct experience. Since this is a rather crude procedure, let us consider a case of accurate measurement. What is the intensity of the electric current which, under the given conditions, must flow in that wire? The position of a pointer on the scale of a certain apparatus gives me the answer in visual terms, the apparatus being part of my visual field, exactly as the wire and the given conditions manifest themselves as parts of objective experience. the same holds for all possible statements and measurements which I shall ever be able to make in physics. My observations of physical facts always remain in the same general class as those which refer to after-images, to the fuzziness which I find in peripheral vision, or to my feeling healthy. Hence, the exactness of my observations in physics cannot be related to an alleged avoidance of direct experience in in physical research. I do not avoid direct experience when I am working in physics; for I cannot avoid it. Yet the procedure works. THus at least some observations which refer to direct experience must constitute an entirely adequate basis for science.
If all concrete statements which I can make in physical research are primarily based on observations within the field of experience, some consequences are plainly inevitable. How do I define my terms when I work as a physicists? Since my knowledge of physics consists entirely of concepts and observations contained in or derived from direct experience, all the terms which I use in this science must ultimately refer to the same source. If I try to define such terms, my definitions may, of course, refer to further concepts and terms. But the final steps in the process will always be: pointing toward the locus of certain experiences about which I am talking, and hints where to make certain observations. Even the most abstract concepts of physics, such as that of entropy, can have no meaning without a reference, indirect though it may be, to certain direct experiences. I shall never be able to give a definition of terms in physics, or to understand such a definition when given by others, which differs in this respect from what I may use as definitions in psychology. Nevertheless, at this point also the method of physics is successful. I never have difficulty with definitions when physicists talk with me about their science. Hence, some definitions which ultimately refer to direct experience must be sufficiently safe for use in an exact discipline. The exactness of definitions in physics cannot result from the alleged fact that in this science definitions are independent of direct experience; for there is no such independence.
But the Behaviorist tells us that observation of direct experience is a private affair of individuals, whereas in physics two physicists can make the same observation, for instance, on a galvanometer. I deny the truth of the latter statement. Even from the point of view of Behaviorism the statement is incorrect. If somebody observes a galvanometer, he observes something different from the galvanometer as physical object. For the object of his observation is the result of certain organic processes, only the beginning of which is determined by the physical galvanometer itself. In a second person, the observed galvanometer is gain only the final result of such processes, which now occur in the organism of this second person. By no means do the two people observe the same instrument then, although physically the processes in one and the other are stated by the same physical object. And yet, in most cases their statements about their observations agree so well that they never ask themselves whether a sufficient similarity of their two experienced galvanometers (and both with the physical object) can be taken for grated. Again, the procedure works. The privacy of direct experience does not disturb anybody - in physics. When working in such a case with others, each individual physicist is naively convinced that his fellow-physicists "have that galvanometer before them." Thus he tacitly assumes that his fellow workers have objective experiences highly similar to this own, and he does not hesitate to take the words of his colleagues as statements about these experiences. According to the Behaviorist this means, of course, that the physicist allows private affairs to play a part in exact science. Curiously enough, this does not seem to disturb the scientific procedure at all, just as it does not disturb the affairs of everyday life, where the same attitude occurs quite generally and naturally. In some cases, therefore, belief in specific experiences of others must be quite harmless, and cannot be regarded as an obstacle to scientific process. Thus, if psychology does not advance more rapidly, the reason for it cannot be that belief as such.
There remains one consequence of the fact that observation in physics is observation within the field of direct experience. As a physicist who observes his apparatus, I do not fear that my activity as an observer has any serious influence upon the characteristics of what I observe - if only I keep myself as a physical system at a sufficient distance from the apparatus as another physical system. And yet, as direct experiences, both the apparatus to be observed and my activity of observing depend upon processes in the same system, namely, my organism. Again the Behaviorist must be wrong when he declares that, because of the inclusion of observer and observed facts in one system, the observation of direct experience has no scientific value. For in the case of physical observation the situation is similar: the material to be observed and the process of observing belong to the same system. Thus we see that the physicist and the psychologist are once more in exactly the same situation. It does not matter at all whether I call myself a physicist or a psychologist when I observe a galvanometer. In both cases my observation is directed toward the same objective experience. The procedure works in physics. Why should it not be used in psychology? There must be some instances in which the observation of facts within the field of direct experience does not seriously disturb these facts.
To be sure, this argument implies a remarkable limitation of the range of its own application. It does not mean that all forms of so-called introspection are justified; even less does it mean that the findings of introspection are quite generally independent of the activity of introspection. Here the critical position of Behaviorism has only exaggerated the scope of a fair argument in unjustly applying it to all statements of direct experience. The critical point as such is well taken in many cases. I have described how, even as a physicist, I must deal with direct experience. It is true, an extremist such as a Behaviorist could derive from this description some doubts as to the objectivity of methods in physics. But fortunately, such doubts had not yet arisen when in the time of Galileo, Newton and Huyghens the first really important steps were taken in physics. These great investigators just went about their business, pragmatically naive and happily undisturbed by a Behaviorism in physics which would have blocked the whole development for the sake of epistemological purity. The procedure worked in spite of the fact that to justify its steps on logical grounds would sometimes have been a difficult task.
Sciences which wish to carry on their research in a productive fashion generally show a healthy disdain for such scruples. It might be better for psychology, if after listening to a wholesome critical lesson from Behaviorism it would also return to its job with more naivete, and use any techniques which yield results. As a scientific attitude, the Homeric assault of Behaviorism against direct experience appears to me very strange. The Behaviorist does not generally show too great an interest in epistemological considerations. It is just one point which suddenly catches his attention: "How can I know about the direct experience of others? I shall never have a definite proof of the validity of such knowledge. But physics that is another matter. There we are safe." The Behaviorist forgets that to prove the existence of an independent physical world is about as difficult as to make sure that other people have experiences. If I were an extreme purist, I might argue the former point precisely as the Behaviorist disputes the assumption of direct experience in others. For some reason it does not occur to him to apply his criticism to the assumption of the physical world. He does not say: "Thou shalt not work upon a physical world, the existence of which will always remain a mere assumption." On the contrary, he assumes the reality of this world with all the healthy naivete which he lacks in psychology. The reason is, perhaps, that the achievements of physical science are imposing, and have become the ideal of Behaviorism. But, as a methodological purist, the Behaviorist ought not to regard mere achievements as satisfactory proof in such matters. Of course, personally I am in this respect as convinced as any Behaviorist has ever been. I am also fully aware of the fact that sciences often believe and postulate where epistemology may have its doubts. But from this point of view I can, of course, also believe that others have direct experience. The decisive point is that this serves to make my work simpler and more productive. To repeat I feel the more justified in this attitude since I find that my work in physics is also founded on direct experience; that in this science the assumption of direct experience in others is made as a matter of course; and therefore, the enormous superiority of physics over psychology cannot derive from any differences in this respect.
At this moment I see the Behaviorist smiling ironically. Probably he wants to say this: "With all his philosophy, Mr. Koehler will never make any headway against sound scientific Behaviorism." My answer is that the basis of Behaviorism is just as philosophical as my criticism: Behaviorism grows on epistemological ground. In this connection the only difference between the Behaviorist and me is one which concerns the width of our visual fields. The Behaviorists sees only a single theorem of epistemology - one person cannot observe another person's experience. As an extremist he dwells exclusively on this point and ignores the context from which it is taken. I am aware of this context; it is stated in the foregoing argument. And, obviously, I prefer to draw my conclusions from this wider view of the situation.
BIBLIOGRAPHY
W.S. HUNTER: Human Behavior 1928.
K. KOFFKA: The Growth of the Mind. 1924. Second edition, 1928.
J. B. WATSON: Psychologies of 1925 (Ed. by C. Murchison).
A.P. WEISS: A Theoretical Basis of Human Behavior. 1925.
