The human species, like all other species, is the product of natural selection. Each of its members is an extremely complex organism, a living system, the subject of anatomy and physiology. Fields such as respiration, digestion, circulation, and immunization have been set apart for special study, and among them is the field we call behavior.
It usually involves the environment. The newborn infant is so constructed that it takes in air and food and puts out wastes. Breathing, suckling, urination, and defecation are things the newborn infant does, but so, of course, are all its other physiological activities.
When we know enough about the anatomy and physiology of the newborn, we shall be able to say why it breathes, suckles, urinates, and defecates, but at the moment we must be content with describing the behavior itself and investigating the conditions under which it occurs—such as external or internal stimulation, age, or level of deprivation.
One kind of relation between behavior and stimulation is called a reflex. As soon as the word was coined, it was taken to refer to the underlying anatomy and physiology, but these are still only roughly known. At the moment a reflex has only a descriptive force; it is not an explanation. To say that a baby breathes or suckles because it possesses appropriate reflexes is simply to say that it breathes or suckles, presumably because it has evolved in such a way that it does so. Breathing and suckling involve responses to the environment, but in no other way are they to be distinguished from the rest of respiration and digestion.
When reflexes first began to be studied in isolated parts of the organism, the results were felt to challenge the role of inner determiners of conduct. Some reflexes, for example, seemed to displace the Rüchenmarkseele—the soul, or mind, of the spinal cord—the defense of which was an early attack on an environmental analysis.
Behavior usually involves the environment in a more complex way. Well-known examples are found in lower species. Courting, mating, building nests, and caring for young are things organisms do, and again presumably because of the way they have evolved. Behavior of this sort is usually called instinctive rather than reflexive, and the ethologist speaks of the environment as “releasing” behavior, a less compelling action than eliciting a reflex response. Released, or instinctive, behavior is also more flexible than reflexive in adapting to adventitious features of the environment. But to say that a bird builds a nest because it possesses a nest-building instinct, or because certain conditions release nest building, is merely to describe the fact, not to explain it. Instinctive behavior presents a more complex assignment for the physiologist than reflex, and at the moment we have few relevant facts and can only speculate about the kinds of systems which may be involved.
When we say that a good prose stylist has an “instinct” which permits him to judge without reflection that a sentence is well written, we mean nothing more than that he possesses certain deeply ingrained behavior of uncertain provenance. We often mean little more in speaking of instincts in general, and there is perhaps no harm in using the word in this way, but much more is often read into the term. A reflex has been described by saying that “stimuli initiate a state of tension that seeks discharge, bringing about relaxation.” “Every instance of instinctive behavior,” said William McDougall, “involves the knowing of some thing or object, a feeling in regard to it, and a striving towards or away from that object.” Feelings are ascribed to the behaving organism when it is said that the moth likes the light it flies toward or bees the appearance and odor of the flowers they frequent. The difficulties raised by the key terms in sentences of that sort—tension, discharge, relaxation, knowing, feeling, striving, and liking—will be considered in later chapters.
Instincts as Driving Forces. A more serious mistake is made in converting an instinct into a force. We are not likely to speak of a force in explaining the fact than an organism digests its food or develops immunity to a disease, but the notion often appears in discussing the organism’s relation to its environment. Herbert Spencer’s “life force,” Schopenhauer’s “blind will to exist,” and Bergson’s “élan vital” were early examples of the conversion of biological processes into more energetic or substantial forms. The élan vital, for example, was said to be “a tireless power continually driving onward and upward.” The Freudian instincts were also treated as driving forces; behavior which led to danger, ill health, or death was said to show a death instinct, while behavior said to be “in the service of life” showed a life instinct, although the observed fact was simply that behavior might have sustaining or destructive consequences.
Two examples which have recently attracted a good deal of attention may be noted: (1) When injured or threatened, an organism is likely to attack—for example, by striking or biting—and, as I shall argue in a moment, some behavior of this sort may be as much a part of the genetic endowment as respiration or digestion, but we have no reason to say that an organism attacks because it possesses an aggressive instinct. The attack is the only evidence we have of the tendency to attack. (2) Some species defend the territories in which they live, and some of the behavior seems to be due to a genetic endowment, but to say that an organism defends its territory because of a territorial imperative or any other kind of instinct is simply to say that it is the kind of organism which defends its territory. (The expression “genetic endowment” is itself dangerous. Like reflexes and instincts, it tends to acquire properties not warranted by the evidence and to begin to serve as a cause rather than as representing the current effects of natural selection, from which attention is then deflected.)
Darwin’s theory of natural selection came very late in the history of thought. Was it delayed because it opposed revealed truth, because it was an entirely new subject in the history of science, because it was characteristic only of living things, or because it dealt with purpose and final causes without postulating an act of creation? I think not. Darwin simply discovered the role of selection, a kind of causality very different from the push-pull mechanisms of science up to that time. The origin of a fantastic variety of living things could be explained by the contribution which novel features, possibly of random provenance, made to survival. There was little or nothing in physical or biological science that foreshadowed selection as a causal principle.
Although we still do not know much about the anatomy and physiology underlying behavior, we can speculate about the process of selection which made them part of a genetic endowment. Survival may be said to be contingent upon certain kinds of behavior. For example, if members of a species did not mate, care for their young, or defend themselves against predators, the species would not survive. It is not easy to study these “contingencies of survival” experimentally because selection is a slow process, but some effects may be shown by studying species which quickly mature to breeding age and by carefully arranging conditions of selection.
Contingencies of survival are often described with terms which suggest a different kind of causal action. “Selection pressure” is an example. Selection is a special kind of causality which is not properly represented as a force or pressure. To say that there is “no obvious selection pressure on mammals that explains the high level of intelligence reached by primates” is simply to say that it is hard to imagine conditions under which slightly more intelligent members of a species would be more likely to survive. (What is wrong, by the way, is the suggestion that “pressure” is exerted primarily by other species. Survival may depend almost wholly on “competing with” the physical environment, when intelligent behavior is clearly favored.)
Contingencies of survival are more easily imagined if the behavior makes it more probable that individuals will survive and breed and if the contingencies prevail over long periods of time. Conditions within the body have usually satisfied both these requirements, and some features of the external environment, such as the cycles of day and night, or the seasons, or temperature, or the gravitational field, are long-lasting. And so are other members of the same species, a fact which explains the prominence given by ethologists to courtship, sex, parental care, social behavior, play, imitation, and aggression. But plausible conditions of selection are hard to find in support of such an assertion as that “principles of grammar are present in the mind at birth,” since grammatical behavior can hardly have been sufficiently important to survival, for a long enough time, to explain its selection. As I shall note again later, verbal behavior could arise only when the necessary ingredients had already evolved for other reasons.
Contingencies of survival cannot produce useful behavior if the environment changes substantially from generation to generation, but certain mechanisms have evolved by virtue of which the individual acquires behavior appropriate to a novel environment during his lifetime. The conditioned reflex is a relatively simple example. Certain cardiac reflexes support strong exertion, as in running away from or struggling with a predator; and there is presumably an advantage if the heart responds before running or struggling begins; but predators vary in appearance, and it is only through respondent conditioning that a particular appearance can elicit appropriate cardiac behavior in advance of running or struggling.
A conditioned reflex, as a thing a person possesses, has no more explanatory force than an unconditioned or innate reflex. The heart of the runner does not begin to beat strongly and rapidly just before a race because of the conditioned cardiac reflex; the reflex is simply a way of identifying the fact that it begins to beat rapidly. The runner has been changed when situations at the start of a race have been followed by strong exertion, and as a changed organism he behaves in a different way. It is merely convenient to identify the changes as the “acquisition of a conditioned reflex.”
Just as we point to contingencies of survival to explain an unconditioned reflex, so we can point to “contingencies of reinforcement” to explain a conditioned reflex. Reflex phenomena, conditioned and unconditioned, have, of course, been known for centuries, but it is only recently that contingencies of survival and contingencies of reinforcement have been investigated.
Inner Supplements. The conditioned reflex is a simple principle of limited scope describing certain simple facts, but many internal states and activities, comparable with the driving force of instincts, have been invented to explain it. The runner’s heart is said to beat fast before the start of the race because he “associates” the situation with the exertion which follows. But it is the environment, not the runner, that “associates” the two features, in the etymological sense of joining or uniting them. Nor does the runner “form a connection” between the two things; the connection is made in the external world. Conditioned responses are also said to occur in “anticipation” of, or in “expectation” of, customary consequences, and the conditioned stimulus is said to function as a “sign,” “signal,” or “symbol.” I shall return to these expressions later.
A very different process, through which a person comes to deal effectively with a new environment, is operant conditioning. Many things in the environment, such as food and water, sexual contact, and escape from harm, are crucial for the survival of the individual and the species, and any behavior which produces them therefore has survival value. Through the process of operant conditioning, behavior having this kind of consequence becomes more likely to occur. The behavior is said to be strengthened by its consequences, and for that reason the consequences themselves are called “reinforcers.” Thus, when a hungry organism exhibits behavior that produces food, the behavior is reinforced by that consequence and is therefore more likely to recur. Behavior that reduces a potentially damaging condition, such as an extreme of temperature, is reinforced by that consequence and therefore tends to recur on similar occasions. The process and its effects have given rise to a large number of mentalistic concepts, many of which will be examined in the following chapters.
The standard distinction between operant and reflex behavior is that one is voluntary and the other involuntary. Operant behavior is felt to be under the control of the behaving person and has traditionally been attributed to an act of will. Reflex behavior, on the other hand, is not under comparable control and has even been attributed to invading wills, such as those of possessing spirits. Sneezing, hiccupping, and other reflex acts were once attributed to the Devil, from whom we still protect a friend who has sneezed by saying, “God bless you!” (Montaigne said he crossed himself even when he yawned.) When no invader is assumed, the behavior is simply called automatic.
There are certain remarkable similarities between contingencies of survival and contingencies of reinforcement. Both exemplify, as I have noted, a kind of causality which was discovered very late in the history of human thought. Both account for purpose by moving it after the fact, and both are relevant to the question of a creative design. When we have reviewed the contingencies which generate new forms of behavior in the individual, we shall be in a better position to evaluate those which generate innate behavior in the species. Meanwhile we may note the importance of insisting upon the distinction.
Imprinting. Operant conditioning and natural selection are combined in the so-called imprinting of a newly hatched duckling. In its natural environment, the young duckling moves toward its mother and follows her as she moves about. The behavior has obvious survival value. When no duck is present, the duckling behaves in much the same way with respect to other objects. (In Utopia, Thomas More reported, the chicks hatched in an incubator followed those who fed and cared for them.) Recently it has been shown that a young duckling will come to approach and follow any moving object, particularly if it is about the same size as a duck—for example, a shoe box. Evidently survival is sufficiently well served even if the behavior is not under the control of the specific visual features of a duck. Merely approaching and following is enough.
Even so, that is not a correct statement of what happens. What the duckling inherits is the capacity to be reinforced by maintaining or reducing the distance between itself and a moving object. In the natural environment, and in the laboratory in which imprinting is studied, approaching and following have these consequences, but the contingencies can be changed. A mechanical system can be constructed in which movement toward an object causes the object to move rapidly away, while movement away from the object causes it to come closer. Under these conditions, the duckling will move away from the object rather than approach or follow it. A duckling will learn to peck a spot on the wall if pecking brings the object closer. Only by knowing what and how the duckling learns during its lifetime can we be sure of what it is equipped to do at birth.
Imitation and the Instinct of the Herd. Natural selection and operant conditioning are often confused when they produce behaviors having similar topographies. The survival value of behaving as others behave seems obvious. If one member of a group responds to an approaching predator by flying, running, or swimming away, and the rest of the group then does the same, all may reach safety although only one has made direct contact with the predator. The conditions are suitable for natural selection because other members are an enduring part of the environment of a species. Nevertheless, very similar behavior is produced by contingencies of reinforcement. In general when a person is behaving in a given way, he is doing so because of prevailing contingencies, and similar behavior on the part of another person in the same situation is likely to be subject to the same contingencies. If one observes people running down a street, one may respond indirectly to the same contingencies by running with them, thereby possibly escaping danger or discovering something interesting. To speak of an instinct of “imitation” or an “instinct of the herd” is ambiguous; it may refer to contingencies of survival or contingencies of reinforcement.
Territoriality and Aggression. These terms do not refer to specific forms of behavior. An organism may defend its territory or attack others in many different ways. Modern warfare is often said to exemplify territoriality and aggression, but it would be hard to find any act of a soldier that could have been selected by contingencies of survival. At best, warlike behavior is acquired because of an inherent capacity to be reinforced by gains in territory or damage inflicted upon others.
Aggressive behavior may be innate and released by specific circumstances in which survival value is plausible. An infant or child may bite, scratch, or strike if physically restrained when it could not have learned to do so. Or the behavior may be shaped and maintained because people are susceptible to reinforcement by signs of damage to others. The capacity to be reinforced when an opponent cries out or runs away would have survival value because a person so endowed would quickly learn to defend himself. Or, third, the behavior may be reinforced by consequences not explicitly related to aggression. Food and sexual contact, reinforcing for other reasons, may reinforce an attack on a competitor if food or a sexual partner is thus obtained.
The intermingling of contingencies of survival and reinforcement causes trouble, and it is not surprising that nativists and environmentalists often disagree and sometimes rather aggressively defend their respective territories.
Species-Specific “Universals.” The term “instinct” is sometimes avoided by referring instead to species-specific behavior on the theory that something characteristic of all members of a species is probably part of its genetic endowment. But contingencies of reinforcement are species-specific too. We have seen an example in the behavior of the duckling that follows its mother because of the “universal” fact that moving in the direction of an object normally brings it closer. Universal features of language do not imply a universal innate endowment, because the contingencies of reinforcement arranged by verbal communities have universal features. Psychoanalysts have made a great deal of the universality of the Oedipus complex, but the contingencies of personal reinforcement in the family in a given culture may be equally universal.
The Importance of Maintaining the Distinction. It is no doubt true that early behaviorists were unduly enthusiastic about the learning processes they were discovering and neglected the role of behavioral genetics, but reactions to the behaviorist position have also been marked by exaggeration. There is no longer any need for controversy, even though we are still a long way from understanding all the interactions between contingencies of survival and contingencies of reinforcement.
In an important sense all behavior is inherited, since the organism that behaves is the product of natural selection. Operant conditioning is as much a part of the genetic endowment as digestion or gestation. The question is not whether the human species has a genetic endowment but how it is to be analyzed. It begins and remains a biological system, and the behavioristic position is that it is nothing more than that.
Quite apart from the details of the resulting behavior, there are good reasons for distinguishing between the two kinds of contingencies. They differ greatly in their bearing on the question with which we began: Why do people behave as they do? Contingencies of reinforcement have the edge with respect to prediction and control. The conditions under which a person acquires behavior are relatively accessible and can often be manipulated; the conditions under which a species acquires behavior are very nearly out of reach. One unfortunate consequence is that genetic sources sometimes become a kind of dumping ground: any aspect of behavior which at the moment escapes analysis in terms of contingencies of reinforcement is likely to be assigned to genetic endowment, and we are likely to accept the explanation because we are so accustomed to going no further than a state of the organism.
The concept of mind had been thoroughly elaborated before the advent of evolutionary theory, and some accommodation was needed. When and how did mind evolve? What kind of mutation could have given rise to the first mental state or process which, in contributing to the survival of the person in whom it occurred, became part of the human genetic endowment? The question is not unlike that raised by the conversion of reality into experience or of thought into action. What sort of physical gene could carry the potential of mind, and how could mind satisfy physical contingencies of survival? If mind is nothing more than a manifestation of physiology, such questions can be answered, or at least postponed without anxiety until physiology can answer them, but not all who subscribe to mentalism accept that position. Mind has been said by some—Teilhard de Chardin, for example—to be the end and purpose of evolution, if not something beyond it. The distinguished scientist Vannevar Bush has put it this way:
We seem, thus, to have arrived at a concept of how the physical universe about us—all the life that inhabits the speck we occupy in this universe—has evolved over the eons of time by simple material processes, the sort of processes we examine experimentally, which we describe by equations, and call the “laws of nature.” Except for one thing! Man is conscious of his existence. Man also possesses, so most of us believe, what he calls his free will. Did consciousness and free will too arise merely out of “natural” processes? The question is central to the contention between those who see nothing beyond a new materialism and those who see—Something.
The behaviorist has a simpler answer. What has evolved is an organism, part of the behavior of which has been tentatively explained by the invention of the concept of mind. No special evolutionary process is needed when the facts are considered in their own right.