The Fundamental Laws of Human Behavior
Being, doing, thinking. Thinking of humanity in terms of thought. The subjective and the objective. Consciousness and nervous function. The nervous system compared with a telephone system. Designing a nervous system. Sensitivity, contractility, conductivity. Differentiation of tissues. An analogy of tissue conductivity. Deformation of the body bringing about change of its situation. Avoiding an obstacle. The story of the snail. A nervous system of impossible design.
WHEN we meet one of the things which surround us in nature, we ask, perhaps more frequently than any others, one of these three questions: What is it? What does it do? What are its thoughts? We know many things with respect to which the first is the only question we ask. We pass through a street which is being paved. When we are told that the blocks of stone put down in regular rows by the workmen, are granite, we are probably entirely satisfied. But when we approach a mill and see the wheels turning, we are not satisfied when we know only that it is a mill. We desire to know what it does, for example, whether it is likely to injure us if we step nearer, or whether it can do special work which we need to have done. When a cow or bull crosses our path, we are again not, satisfied if we know only the animal's name. We are much concerned with the animal's action. Will it compel
( 2) us to change our direction, or can we safely remain where we are? When, thirdly, as school children, we are with our teacher in the class room, we are greatly interested, not only in what he does, but still more so iii what he thinks. If he thinks well of us, we are glad. lout let us raise the question how we know whether our teacher thinks well of us or not, and we must admit that we can not directly know his thoughts, that is, have his thoughts any more than lie can have our thoughts,—that we know it only through our observations of what he does in giving us things, in writing what we may read, in speaking what we may understand. Yet if we are asked whether we are chiefly interested in our teacher's acts or in his thoughts, we are probably quite ready to assert that we regard his thoughts, the existence of which we can not directly know, but only assume, as of far more importance to us than his acts, which we do know directly. In this apparent contradiction lies in a nutshell the problem with which we have to deal in this book. Why do we think of humanity almost exclusively in terms of thought, although our experience contains no other person's thought, but only his behavior? Many other examples could be used to show that a person's thoughts, which nobody can have but himself, are nevertheless of the greatest concern to others who can not know them, can not have them. When parents send their children to school, they send them in order that their intellects may be trained, their characters developed. Let us inquire what is meant by such words as intellect and character. The dictionary tells us that they refer to thought processes, not to particular activities or to a person's appearance. The most important training, then, which every parent strives to give his child, is a training of his powers of thought, of this mysterious unknown.
Not infrequently we hear people speak of brain work and of manual labor. We hear them distinguish. between brain workers and those who work with their hands. The distinction seems quite acceptable. Of course, those who use these phrases do not mean that they know much about the workings of the brain. They simply mean that certain persons, although they do not do much which can easily be seen, are nevertheless active in that they think. They work mentally, as we say. And for this mysterious unknown they often receive a high salary.
Very common is this emphasizing of thinking, this complete or relative disregarding of an individual's doing or being, in ethical valuations. A boy has placed a plank across the street car track and derailed the car. He tells us that he thought that the foundations of the bridge a little distance away had been washed out and that he intended to stop the car and save our lives. Whatever may be the facts in the case, that is, the doing and the being of the water, the bridge, the car, and the boy himself,—we probably praise him for his thoughts and intentions. Or, the boy tells us that he wished thus to injure and punish another boy whom he saw as a passenger on the approaching car. Whatever may, again, have actually happened, visibly and audibly,—for the boy's thoughts we have only contempt, we call them wicked. 'Yet the boy's being and doing is the same in both cases: he looks the same and he has placed the same plank in the same manner across the track. It is again this mysterious unknown, his thoughts, which concerns us chiefly.
The most conspicuous example, perhaps, is to be found in. religious doctrines and ideals. Not good works, but faith decides the test which the Christian has to undergo, according to the Apostle. Not what man does, or what he is, gives him his religious qualification, but his faith,
( 4) that is, his thoughts, again this same mysterious unknown.
In none of these examples are anyone's thoughts known to, that is, had by, any one other than himself. Even an Inquisition, which has power over life and death, is unable to find out what is thought by those whose religious or irreligious thoughts it pretends to investigate. It can find only what is done by them, including, of course, under doing what is written and spoken.
For more than two thousand years a science has existed which has devoted itself to the mysterious unknown which we have just characterized by examples. One may give it the name of mental science, or, rather, mental sciences, for in our modern times science is breaking up into many branches, according to the diversified interests of mankind and in consequence of the limitation of individual mental capacity. Until quite recent years these mental sciences were based upon the conscious experiences of the individual who "professed" the science, upon introspection. During the last few decades the conviction became general that a science of the subjective, an introspective science, because of its limited possibility of generalization, hardly deserved the name of a science. In order to remedy the defect which had been discovered, objective methods, like those used in the physical sciences, were introduced into the mental sciences, to supplement the subjective method of introspection. In the following pages we shall attempt to study by objective methods the most fundamental objective facts which are related to subjective phenomena, and as comprehensively as possible to make clear this relation between objective facts of being and doing and the subjective experiences of our own thinking.
No other fact concerning the relation between the
( 5) subjective (the individual consciousness) and the objective (the world of the natural sciences) can be more impressive, than that consciousness seems to be entirely or, at least, relatively dependent on, conditioned by, the function of an individual's nervous system. So generally is this recognized, that even the extreme assertion that consciousness is impossible without the existence and function of a nervous system, would undoubtedly find a majority of votes among scientists.
This will justify if for the present such a justification seems necessary—our beginning with the study of the nervous system's significance for the being and doing of those objects in nature which are known to possess a nervous system.
We may compare a nervous system with the telephone system of a city or even of a nation, which enables a person to give orders in one place and have them received and executed in another. A nervous system consists essentially of an immense number of string-like structures, very fine and relatively very long, just as a telephone system consists essentially of a large number of conducting wires. However immense the number of these strings may be, they are never found as a disorderly mass, but always arranged according to definite rules. For the sake of understanding clearly the significance of their architectural arrangement for the behavior of an animal—we know that all those things in nature which possess a nervous system, and even many without it, are called animals—let us imagine that we have the duties of a creator and that we have to furnish a given animal with a nervous system of our own design. How, then, should we systematize, that is, put together into a unit, all the strings which we are to insert into the animal's body? The simplest plan seems to be that of uniting all the strings so that one of
(6) the two ends of each string is located in a single point of the body, whereas all the other ends are left unconnected and are distributed among the various parts of the body, like the diagram of Figure 1. Suppose we offered an
animal which has thus far been without a nervous system, a nervous system of this design. Should the animal be grateful for our gift? Would this gift be helpful to the animal in its struggle for life?
In order to answer this question, we must first gain some insight into the life, the being and doing, of an animal which possesses no nervous system. Let us make ourselves familiar with the behavior of a simple animal which we all greatly admired in our childhood days, the snail. It is true, the snail does have a rudimentary kind of a nervous system. But the snail is anatomically so simple that it could almost equally well get along without it. That snail, then, of which we shall now speak, is indeed only an imaginary snail but near enough to reality to serve as an example for the demonstration of certain general laws of animal behavior.
We recall that among the main properties of living matter are sensitivity, contractility, and conductivity.
( 7) In the lowest forms of animals life every particle of the body shows all three of these properties about equally. In the higher forms of animal evolution this is quite different. Our muscles, for example, have but little sensitivity and conductivity. At the expense of these two the third property has been so much increased that the muscles may be called the contractile tissue of our body. In such a case we speak of the differentiation of tissues. Muscular tissue has become differentiated from the rather uniform tissue of lower forms of life, just as in modern society the individual has become differentiated and can, for example, make excellent shoes, but no clothes to cover the other parts of the body, whereas the undifferentiated savage makes tolerably good clothes for himself as well as shoes.
Differentiation of tissues is, of course, not restricted to the one kind just mentioned. Other tissues lose most of their contractility, but become the more capable of conducting any process which happens to go on in one point of them to all their other points. This does not mean that the velocity with which the excitation travels in them becomes much greater. Analogies from physics and chemistry make it fairly certain that the velocity of conduction, the velocity of the current, remains about the same. But the resistance of the conducting tissues becomes much less. Such tissues are the nervous tissues, those strings of which we spoke above and about which we shall have to say much more further on. The main property of nervous tissue is its conductivity, by which the strings are capable of serving like telephone wires conducting electric currents. It is important that, in thinking of increased conductivity of tissues, we do not think of increased velocity of conduction. While we need not deny that the velocity of conduction may be somewhat
( 8) affected by this differentiation, what we mean chiefly is that the excitation is offered less resistance by the nervous tissue than by any other tissue, that it travels through nervous tissue, not more quickly, but certainly more strongly, more effectively than through the non-conductive tissues.
Other tissues, again, differentiate in such a manner that they obtain a highly increased sensitivity at the expense of their other properties. Think of the ease with which we find our way on a dark night when, during new moon, only the stars aid us with their faint light. The sensitive elements on the retina, the background of our eye, respond even to this faint light and stimulate the nerve ends which, through their conductivity, enable the various parts of the body to execute the proper movements. These three properties, however, sensitivity, contractility, and conductivity, are by no means the only properties of living matter. They are merely those properties which chiefly concern us in our present study. In addition, there are many other properties of less importance for our present purpose. If we desire to know more about them and the various ways in which tissues differentiate, we must consult the text-books of the sciences which are devoted to these problems, namely, histology, the science of tissues, and biology and physiology, the sciences of the function of living matter.
We mentioned that the main property of the string-like elements which make up the nervous system, is their conductivity. Let us now apply this knowledge to our problem of the acceptability or non-acceptability of the gift which we offered to our imaginary, nerveless snail. There . is, according to our assumption, and, indeed, practically in accordance with the actual facts, no differentiated tissue in the snail's body. Each particle is
( 9) sensitive, each particle contracts when stimulated, and each particle conducts what goes on therein to the neighboring particles, causing the same process in them.
Suppose, now, the snail, spread out over the ground as when creeping, is very gently touched at the point of the tail end marked in Figure 2. Owing to its sensitivity,
the tissue touched responds. Being contractile the tissue responds by contracting, so that the tail assumes an unsymmetrical form like the one shown in possibly exaggerated manner by the dotted line in Figure 2. The excitation, first caused in the part touched, spreads in consequence of the conductivity of the tissues. What this conductivity means may be made clear by an example taken from ordinary experience. If we drop a small quantity of syrup into a glass of water, we can see how it gradually spreads through the whole fluid until the chemical constitution, different just after the drop fell, again becomes uniform all through the fluid. When we speak of an "excitation" caused in a tissue by a touch, this means, too, that the chemical constitution of the point touched has been changed and that this change tends to spread wherever it can, until the constitution has again become
( 10) uniform everywhere. This spreading is meant when we speak of the conductivity of the tissues. The excitation, then, spreads from the contracted part to all the other parts of the animal's body. Wherever it reaches, contraction of the tissues occurs. But, naturally, just as the syrup spreading out through the water becomes more and more dilute at the starting point, so the excitation spreading out through the body becomes weaker and weaker at the starting point. Finally, perhaps after a second or two, the intensity of the excitation has become quite uniform all through the body, and the contraction, the density of the tissues, has also become equalized all through the body. Only the deformation of the body surface and a weak uniform excitation and contraction of the whole body remain as the effect of the touch.
Now, the chemical state which we have called excitation, means the presence in the tissues of chemical substances which are not normally there. It is natural, then, that the forces which are always active in living matter will tend, after the external influence has ceased, to bring about such spontaneous chemical changes that the normal condition is restored. Gradually, therefore, the normal chemical constitution of the body returns, and as it returns the state of contraction disappears. The body expands again. However, since the previous contraction had become practically uniform in a deformed body, the expanded body, having regained its normal shape, no longer has its previous situation. The deformation by the sudden shrinking occurred on one side; the reformation of form by expansion occurred on all sides of the body. Its axis has slightly turned in the direction indicated by the two arrows perpendicular to the axis of Figure 3.
The application of the few and simple facts which we have just learned, at once reveals their great importance.
( 11) We desired to gain some insight into the life of an animal which possesses no nervous system, in order to answer the question whether a particular nervous system with
which we intended to furnish the animal, would be an acceptable gift to the animal or not. The most important activities of an animal are plainly those of protection and of nutrition. Let us see if we can comprehend the behavior of our snail when it is either in search of food or avoiding an injurious object.
Suppose the snail is creeping on the ground in the direction of the arrow I in Figure 4, Let us take the mechanics of locomotion in the forward direction for granted, so that we may take up at once the more special problem which concerns us here. The snail, creeping forward, approaches the stone which accidentally lies in its way, and the right side of the head comes into contact with the stone. (For simplicity's sake we assume that our imaginary snail has no tentacles.) We know now, from our previous discussion, what must happen. The part which has been excited by the touch of the stone,
( 12) contracts. A little later, expansion of the body occurs, but expansion not only of the part near the stone but of all the body with practical uniformity. The result is a change of position. The axis of the snail now assumes a position more nearly that of the arrow II. The internal conditions whatever they may be—which caused the original forward movement, again become effective. The snail, moving forward, perhaps again comes into contact with the stone. The same happens as before. The axis again turns toward the left. Again the forward movement begins and now, perhaps, is continued without touching the stone; the actual path being approximately that indicated by the solid line.
All this is by no means an extraordinary event in the animal's life, an unusual kind of behavior. It is practically the complete story of the snail. The snail, in order to live, must eat. Lack of food, continued for some time, results in chemical changes in the body. In consequence of structural and functional properties of the body which we cannot study here, these chemical changes bring about a forward movement. A rock (or any other obstacle) lies in the way. If the rock could permanently stop the forward movement, the snail would starve to death. But, in one or several stages, a change of the situation is brought about by a change of the direction of the animal's axis. Now the snail creeps on. Other obstacles which may be encountered are taken in the same way. On its forward march the snail, by accident, sometime passes over edible substances, which stimulate the mouth organs and, consequently, are consumed. Later, lack of food brings about locomotion again, and the same things happen in the same cycle.
One may feel inclined to exclaim: An animal's life cannot be so simple, so automatic as that,—dependent
( 13) on the mere accident that food substances should be in its fortuitous path! But why not? It is true, many a snail will fail to come across any food substances and die of starvation. Such is life! But enough will have better luck and live to propagate the species, for food adapted to the needs of snails is common on earth.
Not only food is obtained in this—if one wishes to call it by that name, mechanical—way; protection against injury is thus made possible too. If the snail instead of approaching a rock, had come near a directly injurious substance, it might have changed its route even before touching that substance; for the tissues of its body are excited, not only by touch, but also by many other influences, for example by a change of temperature, or by the effect of a volatile chemical substance. A piece of camphor instead of a rock would have turned the snail some distance before touch would have been possible. Another important method of protecting itself is that of completely retiring within its shell. This again requires no additional mechanism. We supposed above, that the touch of which we spoke was a very gentle touch. It will, of course, always be gentle if it results from the snail's this slowly moving animal's own motion. If the touch is relatively strong, as when a child touches the snail with a straw, the excitation resulting and spreading with great force all through the tissues must cause, not only the tissues at the point of contact, but also the neighboring tissues, possibly all of the body, to contract vigorously. If the whole body contracts strongly, it must, since a part of it is attached to the interior of the shell, necessarily disappear in the shell. It is to be noted, however, that one kind of behavior is impossible in this kind of an animal, namely, stimulation occurring at one point of the body and contraction occurring exclusively
(14) at an entirely separate point of the body. There must always be what may be called a wave of both excitation and contraction, spreading from the point of stimulation more or less—so little, indeed, in some cases that contraction may seem to be confined to the point of stimulation, or so much in others that clearly the whole body is involved. But the point of stimulation can not in any case fail to be included in and to be the center and starting point of the wave of contraction. Nevertheless, a snail does not need a nervous system in order to live. It can behave in the way in which we have described it as behaving without possessing nervous tissues of any kind whatsoever.
Nevertheless we may wish to appear generous and offer our snail the nervous system of our design in Figure 1. Although the snail can get along without a nervous system, why should it not get along even better when in possession of our gift, we might naively ask. Imagine the snail had accepted the gift and were approaching the rock in Figure 4. The moment when the contact occurs one of the peripheral ends of the nervous strings is excited. The strings are so differentiated that they have an immensely greater conductivity, that is, lesser resistance, than the undifferentiated tissues. The excitation, therefore, is conducted to the point where all the nervous strings are connected and thence with great intensity of flux along all the nervous strings, thus reaching effectively all the parts of the body. Consequently, all the parts of the body contract practically at the same time with great force. A prompt and relatively strong contraction at the point of stimulation, followed slowly by a weak and uniform contraction of the whole body is no longer possible. The resulting change of position is also impossible. The whole body contracts and, after a while, expands again,
( 15) to touch, of course, the rock in exactly the same way that it did the first time. In consequence of the touch, the whole body contracts again. It expands again, contracts again, expands again, contracts again, and so on ad infinitum, until the animal is either exhausted or starved or both. Any way of avoiding the obstacle is impossible. It is clear, then, that the snail would be very much worse off with this kind of a nervous system than without any. Without any nervous system it can live quite well, unless it happens to have exceedingly bad luck. With this nervous system it can not live any more than a human being could live who, whenever he saw or heard anything, instead of normally responding to the situation presented, would invariably have an epileptic fit, a violent and entirely useless unadapted muscular contraction.