New l&as rn Psychol Vol. 8. No. 2. pp. 121-137. 1990 0732-118w90 $3.00 + 0.00

Printed in Great Britain 0 1990 Pergamon Press pk

WHAT KIND OF DISCIPLINE IS PSYCHOLOGY: AUTONOMOUS OR DEPENDENT, HUMANISTIC OR

SCIENTIFIC, BIOLOGICAL OR SOCIOLOGICAL?

MARIO BUNGE Foundations and Philosophy of Science Unit, McGill University, Montreal, Canada

Abstract - The main views on the status and place of psychology are examined, and a new view is proposed. The rejected opinions are that psychology is an autonomous discipline, a branch of the humanities, a component of cognitive science, a biological science, and a social science. It is suggested that, though not autonomous, psychology is a very special science dependent upon other disciplines. It overlaps partially with biology as well as with sociology. But it also has its peculiar concepts, theories, and methods. Consequently psychology is not fully reducible to other disciplines. Such incomplete epistemological reduction contrasts with the full ontological reduction of the mental to the neurophysiological.

THE PROBLEM

Most historians of psychology hold that this discipline broke away from philosophy when psychophysics was established as a separate discipline around 1850 (see, e.g., Boring, 1950). This version of the story is only partially true, and this for two reasons. First, no discipline, even if it adopts the scientific method, can free itself entirely from philosophy, since every research into matters of fact makes use of general concepts and principles about the nature of things and about the search for truth. Besides, every basic discipline approaches some problems of philosophical interest. In particular, psychology cannot push aside one of the oldest and most intriguing of all philosophical problems, to wit, the nature of mind (see, e.g., Bunge, 1980; Popper & Eccles, 1977).

Second, the most popular version of the history of psychology overlooks the fact that classical Antiquity had begat a branch parallel to philosophical psychology, namely, the medical psychology that flourished in the schools of Hippocrates in Greece, and Galen in Rome. These biological schools, contrary to the spiritualism of Plato and his followers, found followers even during the Scientific Revolution. One of them was the physician Juan Huarte de San Juan, author of Examen de ingenios para las ciencius (1575), a best seller in several European languages till the end of the 17th century, and remarkable for proposing the cerebral localization of the various mental functions.

However, it is true that experimental psychology was not born till the mid- 19th century. Medical psychology had been purely observational: It was only based on clinical and surgical work, supplemented only in the last century by the post-mortem pathological examination, which produced the sensational neuro- linguistic results of Broca and Wernicke. As for philosophical psychology, which is as old as philosophy, until recently it was purely speculative and it ignored the

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findings of the medical psychologists: It was cultivated as a branch of the humanities.

Curiously, we know the birth certificates of psychology, in particular that of experimental psychology, but we do not know for sure where to place it in the system of human knowledge. The spiritualist philosopher and psychologist Maine de Biran (1823/24), as well as the contemporary “humanistic” clinical psychologists (e.g., Maslow, 1962; Rogers, 1961), and even the psycholinguists of the Chomsky school (e.g., Fodor, 1975), have conceived of psychology as a humanistic discipline, hence as one alien to experiment, biology, and sociology. On the other hancl the radical behaviorists, from Watson (1913) to Skinner (1938), as well as the neobehaviorists, from Hull (1952) to Suppes (1975). have regarded psychology as a natural science-for dealing with animals-though, paradoxically, as an autonomous one and, in particular, as independent from biology.

Actually neither of the two preceding opinions-that psychology is a humanistic discipline, and that it is an autonomous science-is dominant in the international psychological community. In this community the dominant view is that basic psychology is a science on the same footing as physics, though admittedly not as advanced, whereas clinical, educational, and industrial psychology are applied sciences or perhaps technologies similar to engineering, for their aim is not ,just to study behavior, emotion, and cognition, but to alter them.

However, the scientific psychologists are not agreed on whether psychology is a natural or a social science. Most of them, from Darwin (187 1) ancl Lloyd Morgan (1894)-the founders of comparative psychology-to the radical behaviorists, the Gestalt school, and the researchers in psychophysics and in physiological psychology, conceive of psychology as a biological science, even though not all of them make explicit use of the concepts, hypotheses, and methods of biology. A minority, formed by some social psychologists and the followers of Vygotsky (1978), place psych&ogy among the social sciences. The former argue that psychology is a natural science because it stuclies animals; the latter argue that psychology is a social science because it cannot ignore social behavior and social stimuli.

So far, then, we have four different opinions on the nature and place of psychology: Autonomism, humanism, naturalism, and sociologism. All four views have been institutionalized. The autonomists have succeeded in establish- ing some faculties of psychology, particularly in Latin countries. The humanists work in faculties of arts or devote themselves to private practice. The naturalists are thriving in the faculties of science and of medicine, and the sociologists are distributed among the faculties of arts and of education.

This institutional fragmentation results in a very uneven training. Those who have studied in faculties of arts tend to be bookish, speculative, and dogmatic: They tend to work on authors rather than on problems. The graduates of faculties or departments of social sciences are competent to conduct observations and the odd experiment, as long as it does not involve any biological techniques: They sidestep the nervous system, hence they ignore the very existence of

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physiological social psychology. On the other hand, those who have studied in faculties of science or of medicine feel comfortable in laboratories or hospitals, but they tend to overlook the social matrix of behavior and inner life.

As a result of this institutional fragmentation, the student who begins the study of psychology usually forms a one-sided view of the subject: He or she tends to think of it either as an autonomous science, or as a chapter of the humanities, or as a branch of biology (or even of medicine), or as part of sociology. Neeedless to say, neither of these one-sided views embraces the totality of psychology, which actually trespasses on many disciplinary borders, as will be seen in the sequel.

The subject of this paper has then a three-fold interest. On the one hand it is a problem in the philosophy of science, as much as that of the location of logic or of linguistics in the system of knowledge. On the other hand the problem is relevant to the choice of research method as well as the background knowledge presupposed by psychological research. In the third place, ours is a problem of university organization and policy: Do we want psychology to be studied in faculties of arts, or of science (and medicine), or should we push for an independent faculty?

In order to solve the practical problem we must begin by solving the conceptual problem, namely, what kind of facts does psychology study- spiritual, biological, social, or mixed, and how does (or ought) it to study them? Let us then start by tackling this question, after which we shall examine the merits and shortcomings of the four main theses concerning the nature and place of psychology.

WHAT DOES PSYCHOLOGY STUDY AND HOW DOES IT GO ABOUT?

Even a quick perusal of the contemporary psychological literature shows that psychologists study the behavior and the inner life (emotional and cognitive) of the higher vertebrates. Actually most psychologists restrict their interest to primates, in particular humans, and their pets; the remaining animals are studied by zoologists, ethologists, and physiologists.

Now, there are two ways of conceiving of overt behavior: Either as a fact in itself, that is, as a primary given, or as a manifestation of neuromuscular (or neuroendocrinomuscular) processes. The behaviorists adopt the first aproach, that is, they limit themselves to observing and describing behavior without asking for its source, hence without attempting to explain it. On the other hand the psychobiologists (or biopsychologists, or behavioral neuroscientists), in parti- cular the physiological psychologists, try to explain overt behavior as a result of muscular processes controlled by neural systems influenced by the endocrine system and modulated by sensory stimuli. According to these psychologists, behavior is the last link of a chain that starts in the nervous system or, rather, in the neuroendocrine supersystem.

For example, a radical behaviorist may describe the manner in which a monkey presses a button that activates a mechanism which delivers a peanut. He finds that, after a certain number of trials (variable from one animal to the next), the animal has learned to associate the cause (pressing the button) with its effect

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(delivery of the peanut). Although this result is of some interest, it cries for explanation.

The psychobiologist attempts to explain this behavior pattern by conceiving hypotheses about the neuromuscular (or neuroendocrinomuscular) process involved in it. And, being a scientist, he puts them to the test with the help of stimuli and recording mechanisms of various kinds-mechanical, electrical, chemical, etc. By working in this manner the psychologists, allied to the neurophysiologists, have succeeded in localizing the neural centers of voluntary movement of the primate in the frontal lobes (e.g., Evarts, Shinoda, & Wise, 1984).

As for the mind, the radical behaviorist denies its existence or at least he denies that it may be studied scientifically. (The former adopts an ontological behaviorism of positivistic origin, the latter a methodological or opportunistic behaviorism.) The antimentalist dogma snaps the thread of tradition and it makes a present of the entire domain of inner life to the charlatans. Fortunately the European psychologists, particularly those of the schools of Wertheimer and Piaget, as well as of Bartlett and a few others, ignored the North American fashion of the 192Os, 1930s and 194Os, and went 011 with the scientific study of memory, conceptual learning, imagination, concept formation, hypothesis making, inference, will, and other categories of psychological phenomena.

Regrettably these researchers restricted themselves to describing, measuring, and altering experimentally those phenomena, without going into their mechanisms. They dealt only with black boxes and, as a consequence, they explained nothing. Moreover, they made a number of errors for trusting self- observation, or introspection, in an uncritical manner. For example, the Gestalt school held that every perception is global and prior to analysis. We now know that this is not always the case: That the perception of a whole as such, for example, that of a figure or a melody, may be preceded by analysis (see, e.g., Treisman & Paterson, 1984). We have also learned that the analysis of the sensory stimulus is in charge of specialized (“feature”) neurons (see, e.g., Hubel, 1982; Wiesel, 1982).

From the time of Karl Lashley ( 1929, 194 1) and his disciples, in particular Donald Hebb (1949, 1980) and Hans-Lucas Teuber (1978), the biologically oriented psychologists took over the entire problematics of classical psychology, treating the mental phenomena as neurophysiological processes (see, e.g., Bindra, i976; Dimond, 1980; Olds, 1975; Thompson, 1975). One of the most fruitful and best confirmed hypotheses investigated by this school is the conjecture of the cell assembly, proposed by Hebb (1949) and modified by Milner (1957) before there were experimental data in its favor. Curiously enough, this hypothesis had been originally formulated by the Italian physio- logists Tanzi and Lugaro, and it had been enthusiastically adopted by Rambn y Cajal. Regrettably, it was totally ignored by the psychologists until Hebb reinvented it seven decades later.

According to Hebb, learning would consist in the formation of an assembly or system of neurons. The basic mechanism of the emergence of such a system would be the reinforcement of the synaptic connections among the neurons

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constituting the system. (Every neuron may have about 1,000 connections with its neighbors.) These connections are not anatomical but chemical: They are effected by neurotransmitters such as serotonin and dopamine, which combine with receptor molecules situated on the membrane of the adjacent (postsynaptic) neuron. Besides these neurochemical processes there are anatomical processes of formation, growth, and pruning of dendrites and synaptic boutons. These processes of morphological alteration, which contribute to changing the connectivity of a cell assembly, have recently been filmed in vivo as well as in vitro, and they can be stimulated or inhibited by physical and chemical means.

The ability or disposition of a neuronal network to change its connectivity as a result of anatomical or neurochemical changes is called “neuronal plasticity.” A system of neurons the connectivity of which can change rapidly in the course of time, that is, a plastic neuronal system, may be called a “psychon” (Bunge, 1980), due to the Tanzi-LugaroHebb hypothesis that a mental process is one that happens in a neuronal system composed of many cells joined by plastic (rather than elastic) synaptic junctions. The lasting enhancement of the strength of such junctions is called “long-term potentiation,” and it is one of the most lively research subjects in recent biopsychology (see, e.g., Larson & Lynch, 1986).

By confirming the Tanzi-Lugaro-Hebb hypothesis, research on neuronal plasticity has revolutionized psychology. By the same token it has toppled two myths: Innatism, and the view that the architecture of the brain resembles, in its alleged rigidity, that of a computer. We have learned in recent years that connectivity, far from being rigid, changes as we learn and forget. We have also learned that, in contrast to other parts of the body, the brain of the higher vertebrate is to a large extent a product of its experience and, consequently, it is partly self-made. Presumably, the brain of a mathematician is physiologically different from that of a painter, and the latter different from that of a psychologist.

Nowadays the basic psychologists tackle, then, the entire problematics of traditional psychology plus that raised by behaviorism and by the biological approach. They study the behavior and the mental life of the higher vertebrates, particularly the primates, and they do so by using the scientific method as well as psychological, physiological, biochemical, biophysical, and sociological concepts and methods. Whereas some of them settle for observing and describing psychological phenomena on their own level, others attempt to explain in terms of neuronal, neuromuscular, neuroendocrine, and even neuroimmunological mechanisms. While some of them design and conduct experiments, others invent hypotheses and even mathematical models.

Present day scientific psychology is, in short, theoretical as well as experi- mental, and it rejects no genuine psychological phenomenon. It even studies, once in a while, the phantasies of parapsychologists and psychoanalysts, albeit with monotonous negative results (see, e.g., Alcock, 1981; Wolpe, 1981).

PSYCHOLOGY AS AN AUTONOMOUS DISCIPLINE

If psychology is defined as the study of the psyche (mind, soul, or spirit), and in turn the psyche is conceived of as an immaterial entity, it follows that

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psychology must steer clear of biology. On the other hand, it might be included in social science provided the latter- were viewed as the study of the adventures (and misadventures) of the human spirit-the way it was conceived of by the historico-cultural (or humanistic) school of Dilthey and his followers. Or, again, psychology might be regarded as one of the cognitive sciences dealing with knowledge in itself, apart from knowing brains and their social matrix (regarding which, more in the next section).

Psychophysical dualists, for whom mind and matter are distinct entities, have always regarded psychology as either an autonomous discipline or as a chapter of the humanities or, at most, as a social science. This applied in particular to Brentano (1955/1874), for whom the mental differed radically from the physical for having an “intentionality” or reference to something else. It also holds fix-

Fodor ( 198 1, 1983), according to whom minding is information processing (whether in man, computer, or disembodied spirit), and mind an immaterial whole divided into “modules” or water-tight compartments-a new-fangled version of the old psychology of faculties.

Psychological autonomism is mistaken for several reasons. First, the study of behavior and subjective experience is superficial unless one searches for its sources in the neuronal, endocrine, and immune processes. This search calls for a close cooperation, nay for the fusion, of psychology and neurobiology (Lashley, 1941; Teuber, 1978); actually it requires the strengthening of psychoneuroendocrinoimmunology.

Second, the declaration of independence of psychology entails the condem- nation of physiological, developmental, evolutionary (or comparative), and social psychology, all of which are mongrel disciplines, for they employ concepts and methods invented outside the domain of pure psychology.

Third, a fully autonomous discipline cannot be part of the system of the sciences, since these constitute a system by virtue of their partial overlapping and their interactions. Of course some division of labor is necessary, but such division should not be carried to the extreme of isolating the various sciences, if only because every division of scientific work is largely conventional. An understand- ing of the artificiality of that division of labor facilitates the integration of psychology with neurobiology, endocrinology, immunology, medicine, anthro- pology, sociology, and the so-called sciences of education.

The isolation of a discipline from the total system of the sciences is a reliable indicator of its nonscientific character (Bunge, 1983). ‘I‘hink of parapsychology and psychoanalysis, both of them incompatible with experimental psychology and biology. Remember that Freud (1929) demanded the total independence of psychoanalysis from experimental psychology and physiology. He even pro- posed the establishment of a Faculty of Psychoanalysis, which would include humanistic disciplines but would exclude biology and social science-so as to keep the future analysts innocent of the experimental method and the workings of the brain. Lacan (1966) went even farther, by holding that psychoanalysis, far from being a science, is the practice of the symbolic function, hence far closer to rhetoric than to biology.

Psychological autonomism is not only scientifically barren, it is also impracti-

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cal, for being unable to help correct any disturbances in behavior, affect, or learning. It cannot be effective because it assumes that the mind has a life of its own, although it can influence the body. Thus psychophysical dualism prevents autonomism from utilizing the resources of psychopharmacology and neuro- surgery, as well as the techniques of behavior therapy (e.g., desensitization), since all of these rest on laboratory research. Take pity on the manic-depressive, the paranoid, the autistic, the phobic, or the mentally retarded who falls into the hands of a logotherapist. Poor nervous system and poor bank account!

In short, there is no merit in the autonomy thesis. It consecrates the myth of the immaterial mind, it blocks the biological investigation of mental processes, and favors the pseudoscientific approach to the psychological problematics.

PSYCHOLOCY AS A BRANCH OF COGNITIVE SCIENCE

It. has become fashionable to say that psychology has joined forces with linguistics and artificial intelligence, to constitute a new discipline, called “cognitive science.” The three belong together, it is argued, because each of them deals in its own way with information processing, in particular with the transformation of mental representations (see, for example, Pylyshyn, 1984).

The idea of forming a cognitive science separate from the other sciences raises the following objections. First, the proposed segregation entails the splitting of psychology into two parts: Cognitive and noncognitive. This division is mistaken because there is no learning without motivation, emotion, or ostensible behavior. There is none because the cerebral cortex interacts vigorously with the limbic system and the hypothalamus, and because the cortico-limbic system interacts with the endocrine system as well as with the viscera and the muscles. In short, anatomy and physiology do not honor the cognitive-noncognitive splitting.

Second, the account of behavioral and mental processes in terms of information processing is incorrect because, unlike the signals that travel through a communications network, those that travel through the nervous system have different effects according to the state of the receptors on the postsynaptic membranes. In the nervous system there is no message indepen- dent of the receptor: What the addressee receives depends not only upon the messenger but also upon the state in which the addressee happens to be. This is why it is impossible to intercept and decode nervous “messages” similarly to the way one can tap a telephone communication. In any event, the “information” said to be processed by the mind is not a signal carrying an unambiguous message, but a physico-chemical process that becomes information proper if and when it activates in a proper way the suitable cognitive neural system when in a favorable state. The word “information” is to be avoided in psychology and neuroscience for having at least seven different significations (Bunge & Ardila, 1987).

Nothing of the above is intended to discourage strong interactions among cognitive psychology (in particular physiological cognitive psychology), lin- guistics (in particular psycholinguistics), and knowledge engineering or artificial intelligence. On the contrary, such interactions are to be welcomed, but not at the price of the integrity of psychology, the impoverishment of the study of

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behavior and emotion, or in exchange for adopting the coarse brain-computer analogy. Artificial intelligence has much to learn from psychology, particularly from physiological psychology, if it is to make any breakthroughs in the simulation of mental processes. Linguistics, particularly psycholinguistics, would be far better off in departments of psychology or of anthropology than in separate units devoted to knowledge in itself, in abstraction from knowing brains and their social matrix.

In short, although it is better for cognitive psychology to consort with linguistics and engineering than to remain isolated, it is a serious mistake to cut it off from the rest of psychology as well as from the natural and social sciences. After all, cognitive psychology is about cognition, not about knowledge in and of itself, and cognitive processes take place in living brains.

PSYCHOLOGY AS A NATUKAL SCIENCE

If it be admitted that animal behavior and mental processes are biological processes, it would seem to follow that their study, i.e., psychology, is a branch of biology. As a matte1 of fact, ethology is usually cultivated in zoology departments, and physiological psychology flourishes particularly in biologi- cally oriented departments of psychology, as well as in departments of neuroscience and in neurological institutes and psychiatric hospitals not contaminated by psychoanalysis.

Yet, there are other branches of psychology, in particular cognitive psycho- logy, which are not often studied from a biological viewpoint. (However, cognitive ethology and the biology of knowledge are advancing rapidly: See, e.g., Marler & Terrace, 1984.) But, before deciding whether there can be nonbiological branches of psychology, we should distinguish fact from ideal. The fact that at the present moment a given branch of psychology, such as personology, is not being approached systematically in a biological manner, does not imply that it deals with nonbiological (e.g., spiritual) phenomena.

Like other old disciplines, psychology follows a tradition or, rather, several traditions, in particular the mentalist or spiritualist on the one hand, and the biological or materialist on the other (see the first section of this paper). The currently fashionable information-processing psychology, according to which the mind is a collection of programs, follows the mentalist tradition, since the software is detachable from the hardware (Bunge, 1985).

It is perfectly possible to make constructive contributions to psychology by placing oneself in either of the two traditions, the mentalist or the biological one. That is, one can make psychological discoveries and inventions whether one asserts or denies that behavioral and mental processes are physiological processes. For example, Wertheimer, Kahler, Piaget, Vygotsky, Bartlett, and several others made important contributions to cognitive psychology without paying much attention to the nervous system, whereas Hebb (1949), Bindra (1976), and a few others explained some of those findings in neurophysiological terms.

For example, the stages in cognitive development, discovered and described by Piaget (though denied by the behaviorists), may be explained as the outcomes

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of neuronal rewirings in the course of the individual development of the central nervous system (Thatcher, Walker, & Giudice, 1987). Another example: The learning laws can be explained in terms of the formation of new cell assemblies in the plastic regions of the brain. The biological approach to behavior and the mind generalizes and deepens the shallow or molar approach, which overlooks the nervous system. (Parallels: The absorption of kinematics by dynamics, and of geometrical optics by wave optics.) Note that in this case, like in every other scientific revolution, many of the past acquisitions have not been swept away; they have been improved and explained. There are no total scientific revolutions & la Kuhn (Bunge, 1983).

The view of psychology as a biological science, then, has obvious advantages. By studying behavioral and mental phenomena as biological processes one may make free use of some of the concepts and methods of biology, and one may go from description to explanation. (Every explanation invokes some mechanism, and every mechanism proper is material: There are no behavioral or mental mechanisms, but only neuronal, neuromuscular, neuroendocrine, or neuro- immune mechanisms.) This is how the biological approach has made sensational contributions over the past half century.

Let us draw a small random sample of the collection of achievements of biopsychology. The electrical stimulation of the hypothalamus causes rage, that of the limbic system may cause pleasure, and that of the cerebral cortex may evoke long forgotten memories or cause the perception of the scent of an absent flower (see, e.g., Penfield & Perot, 1963). The ablation of the hippocampus and the amygdala causes irreversible damage to memory; however, it is possible to forget episodes without losing habits (Mishkin, Malamut, & Bachevalier, 1984). Some patients who have lost short-term memory can learn new motor tasks, because the know how organ is not the same as the know that one (Schachter, 1983). Animals prevented from using one eye during the first few weeks after birth (critical or plastic period) never acquire binocular vision (Hubel, 1982; Wiesel, 1982). Human subjects deprived of sensory stimulation lose the perception of time and hallucinate, as Hebb found long ago. The destruction of the frontal lobes eliminates the ability to decide and plan-as found with thousands of lobotomy patients, or rather victims. (For more examples and an examination of some of their philosophical implications, see Bunge & Ardila, 1987.)

The postulated identity of mental processes with neurophysiological processes occurring in plastic neural systems has a second advantage: It facilitates the construction of mathematical models. In fact, if all the psychological variables are physiological variables, or functions of the latter, then the psychological processes can be modeled in the same way as the physiological, chemical, or physical ones. For example, the learning of the association between two stimuli, or two mental representations, may be modeled as the formation of a neuronal system composed of two initially independent systems, the link or connectivity of which is strengthened by experience. [The state functions A and B of the two initially independent systems are modified in such a way that B becomes a function of A. In the model proposed by Anderson, Silverstein, Ritz, and Jones

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(1977), B = CA, where A and b’ are column vectors, and C is a square matrix.] A consequence of the physiologization of psychological variables and their

mathematization is a third advantage, namely, a remarkable enhancement of the degree of testability of the psychological hypotheses and theories. (For the dependence of testability upon precision, see Hunge, 1983.)

A fourth merit of the biological approach to the mind is of a philosophical nature: It puts an end to psychophysical dualism, that old usyluttt i~qnomnticu and ally of all kinds of beliefs in the supernatural. This is an advantage because, b) claiming to explain everything in terms of global categories, such as those of body, mind, and interaction, dualism explains nothing at all, for it proposes no

definite mechanisms. On top of this, dualism postulates the existence of a substance inaccessible to experiment, namely the mind (or soul, spirit, or I-Y\ co$zr~s), that would be immaterial and perhaps immortal as well. Also, dualism perpetuates the influence of religion on the study of the mental, an influence that has blocked the scientific understanding of subjective experience.

Finally, the biological approach eliminates the ontological anomaly of mentalist psychology, the only discipline that claims to study states and changes of state other than states of concrete things or changes in the latter. ‘I‘he biological approach unifies all of the ontologies underlying the various factual sciences-without however forcing upon us a physicalist ontology that ignores the peculiar properties of grey matter, the only genuine YPS c.o,.yitcmc (see

‘Psychology as a biosociological science,’ below).

We humans are essentially social animals: Only a philosopher or an academic economist could imagine that, at bottom, each of us is a Robinson Crusoe. We all learn from others, whether directly or through cultural media. Not only OUI

cognitive but also our affective development is strongly influenced by the societ) in which we live, as shown by the large emotional differences between children brought up in orphanages or in boat houses, on the one hand, and those who develop in a normal social environment. ‘I‘hese emotional differences are even more marked in the case of experimental animals reared in individual cages, as Melzack and Scott (1957) found long ago.

The preceding suffices to do and teach social psychology. ‘I‘his discipline studies the impact of social life upon behavior and inner experience, as well as the reactions of both to social structure. The former subject is that of psychological social psychology, and the latter that of sociological social psychology (Rosenberg 8c Turner, 1981). ‘I‘he former is cultivated by psycho- logists and the latter by sociologists. This explains why social psychology is done and taught in departments of sociology as well as in departments of psychology.

Social psychology had a vigorous beginning. For example, between the 1930s and the 1950s it was found that poor children perceive dimes bigger than their rich counterparts, that group pressure may be suggestive to the subject to the point of making it believable that a fixed point is moving, that a couple of years in school may awaken the deductive ability, and that rumors propagate like epidemics and according to a precise mathematical formula (Maccoby,

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Newcomb, & Hartley, 1958). In recent years we have learned that the contemplation of violent scenes increases aggressiveness instead of having the cathartic effect claimed by the psychoanalysts, and that the experimental subject usually wishes the experiment to succeed, as a consequence of which he or she tends to report that he or she perceives or feels the way the experimenter has hypothesized he or she should.

In more recent times there have been some serious problems with the interpretation of the effects of group pressure on the emotional states of drugged subjects, as well as on the willingness of people to inflict pain on experimental subjects. These controversial results have cast some shadow on the discipline. However, there is no reason to disbelieve in its future. After all, scientific research is subject to error: What characterizes science is not the absence of error but the ability and willingness to detect and correct it.

It is obvious that the social animals must be studied not only as organisms but also in their mutual relationships. In particular, we humans are not only what our ancestors bequeathed to us but also what we learn and do. Every one of us performs as many roles as social groups in which we participate: Family, school, gang, work place, club, church, political party, etc. This is why every one of us manifests a somewhat different personality in each social group. Therefore a purely biological (in particular genetic) theory of personality is doomed to failure.

There are, then, reasons for conceiving of psychology as a social science. But they are hardly sufficient, because the central referent of every psychological proposition is an individual. The social group appears as the environment of the individual and therefore as a peripheral referent of the proposition. Similarly, economics must take the physical environment into account, but the latter is a peripheral referent of the discipline, the central referents of which are economic systems, such as households, firms, and markets.

In other words, the behavioral and mental processes are biological even though they are influenced by the social context. This is why these influences can be studied not only in the classical, prebiological, way, but also physiologically; this is precisely the point of social psychophysiology or physiological social psychology (Cacioppo & Petty, 1983). On the other hand social processes are changes that occur in social systems. Psychology studies individuals-in-society, not social systems. The social sciences study the latter: The individual does not interest them except as a component of such systems. Analogously, the geologist is centrally interested in the lithosphere, even though he or she cannot ignore the action of the atmosphere on the latter. For this reason geology and meteorology are regarded as components of the scientific system called “earth sciences,” instead of including geology in meteorology or vice versa.

We see then that psychology is not a social science even though it cannot ignore the social matrix, just as biology is not an earth science even though it cannot ignore the habitat of every biopopulation. Not even social psychology is a social science. What must be said is that this science belongs as much in natural as in social science, that is, it is in the intersection of the two research fields. Other sciences belonging in this intersection are ethology, biosociology, and demo-

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graphy. By the way, the mere existence of these hybrid sciences refutes the idealist thesis, formulated by Kant and defended by Dilthey, that there is an unbridgeable chasm between the natural and the social sciences (“sciences of the spirit”-Ge~teswi.s.senschaften-or sciences morales). There is no chasm; there is partial overlap.

PSYCHOLOGY AS A BIOSOCIOLOGICAL SCIENCE

If animal behavior and the mental (affective and cognitive) processes are conceived of as biological processes, it follows that psychology is, at least in part, a life science. If we take into account that much of what happens to and in an animal is in part determined by its social environment, it follows that psychology is also, at least in part, a social science-or at least that it must interact vigorously with the social sciences, particularly anthropology and sociology. Accordingly, psychology would be a biosociological science: it would belong in the intersection of biology and social science. However, we shall see in a moment that this is only an approximate solution to our problem.

This solution to the problem of the place of psychology in the system of the factual sciences involves a reduction without leveling. Let me explain. The hypothesis that the mind is the same as a collection of brain activities or functions of a certain type (those happening exclusively in plastic neuronal systems) is a reduction of an ontological type. It is a reductive proposition of tl& same kind as the reduction of heat to the random movement of atoms or molecules, or of light to electromagnetic radiation of wavelengths in a certain interval. What in a previous stage of the history of science had been conceived of as a separate realm is now seen as included in a larger class of facts (Figure 1).

(a) (b)

Figure 1. (a) Classical trichotomy of the collection of facts involving humans or other gregarious higher vertebrates: Biological (p), social (a), and mental (~0). (b) Inclusion of mental facts (I#) and those of individual behavior (IB) in the collection of biological facts @), and of the facts of soc’ial behavior (SB) in the intersection of the collections of biological (fl) and social (a) facts. This ontological reduction does not entail the full epistemological reduction of the

corresponding disciplines (see Figure 2).

What kind of discipline is psychology? 133

Biopsychology is then reductionist in an ontological sense. In particular, it reduces emotion to certain processes in the limbico-hypothalamic system, memory to the strengthening of certain interneuronal connections, learning to the formation of new neuronal systems, and consciousness to the representation in a neuronal system (the monitor) of processes occurring in another neuronal system (Bunge, 1980; Bunge & Ardila, 1987).

Yet, despite being reductionist, biopsychology is not leveling; it does not assert that the mental processes are physico-chemical or even intracellular processes. Far from being microreductionists, in particular neuronists (one idea-one neuron), by far the greatest number of biopsychologists hypothesize that every mental process is a change in the connectivity of a network composed by thousands, millions, or even billions of neurons. In other words, the mental is an emergent property of such systems, a property that its cellular components lack. In this regard the mental is just as emergent as heat, the appearance of a new biospecies, or of the social. (For a precise elucidation of the concept of emergence see Bunge, 1979.)

Compare this thesis with its two main rivals: Spiritualism and neuronism. If the mental is not biological, then it cannot be studied by biologists, which eliminates psychobiology. If on the other hand it is granted that the mental is biological but not emergent, then it must be possible to discover it in the individual neuron. (This would be the famous “pontifical neuron” or “grand- mother’s neuron.“) As a matter of fact a few psychobiologists, such as Konorski, Blakemore, and Dimond, have held this thesis, which may be called ‘neuronism.’ For better or worse there is not a shred of experimental evidence in its favor. On the other hand, it is well known that no observable behavioral or mental deficits appear unless systems constituted by thousands of neurons are destroyed, disconnected, or inactivated if only temporarily. This is strong evidence for the emergentist hypothesis instantiated by the Tanzi-Lugaro-Hebb conjecture about learning (see the second section of this paper).

Now, if there are ~OUU de re, i.e., factual novelties, we must conceive of new ideas (nova de ditto) to account for them. That is, the emergent things, prop&ties and processes must be represented by new concepts, hypotheses and theories. This is precisely what happens with psychology: This discipline cannot make ends meet with the means supplied by biology, but must also employ typically psychological concepts, such as those of affect, mental representation, thought, and decision. True, these concepts are reducible, at least in principle, to biological concepts. But reduction, far from eliminating ideas, allows us to deepen, elucidate, and interconnect them. In other words, by becoming (partially) biological, psychology does not disappear as a special science but becomes a deeper science.

We have then ontological reduction without leveling, i.e., without denying the existence of levels of organization. We also see that psychology is not eliminated by becoming partially biological: It simply loses its independence. Analogously, astronomy did not disappear but, on the contrary, was enormously enriched when it was rethought as the physics of celestial bodies. Meteorology became a science proper when it was conceived of as the aerodynamics and thermodyna-

134 M. Hunge

mics of the atmosphere. Genetics was remarkably deepened when genes were shown to be segments of DNA molecules. Finally, history was revolutionized when it was recast as the science of social (economic, political, and cultural) changes.

Let us emphasize that the reduction of some or even all psychological concepts to neurobiological ones does not entail the full reduction of psychology to biology. This is because not all psychological propositions become biological propositions. In fact, social psychology cannot dispense with sociological concepts irreducible to biology, such as those of social group, crowding, poverty, commodity, work, marginality, and antisocial behavior. What social psychology does is to solder psychology and social science rather than reducing the former to the latter or conversely. Example: “Crowding increases stress.”

In sum, we propose the reduction of psychological facts to biological ones but not the full reduction of psychology to biology. Since the behavioral and mental

processes are socially conditioned, what is appropriate is a pa&l biosociological

r-duction. This partial reduction comes together with the acknowledgment of emergence both ontological and epistemological. Hence, the reductionism we propose is moderate rather than radical (Figure 2).

CONCLUSION

We have argued that scientific psychology is not an autonomous science but that it interacts strongly with biology and social science, to the point of overlapping partially with these two sciences, as suggested in Figure 2. We have therefore adopted a reductionism of a moderate type because it admits that the mental constitutes an emergent category or even level, and that psychology has ideas and methods of its own which are neither strictly biological nor purely

BIOLOGY

ii

BIOLOGY

1850 1950

Figure 2. Relations between psychology and its neighbors: From yesterday’s independence to today’s interdependence. f3~ = Biopsychology. qv”v = Psychological social psychology (including physiological social psychology).

CJCJIJI = Sociological social psychology.

What kind of discipline is psychology? 135

sociological, although it utilizes all the biological and sociological tools it can get hold of.

This moderate reductionism allows us to continue to talk of psychology as a distinct and very special discipline but not one detached from the other sciences. But at the same time our moderate reductionism favors the integration of the various branches of psychology, as well as the fusion of the latter with biology and social science. (For the concept of f-usion or merger of theories and research fields as a complement of reduction and a factor of integration, see Bunge, 1983.) Such integration, which has lately been much in demand in the psychological community, cannot but favor the advancement of psychology, since the borders between research fields are largely artificial obstacles to the circulation of ideas and methods.

Finally, psychology can be done, applied, and taught wherever there are good researchers, practitioners, and teachers endowed with suitable resources and acting in a favorable environment. Such groups can flourish in many different places. However, the ideal administrative unit-department or institute-is perhaps one grouping experimental and theoretical psychologists; neuroscien- tists keenly interested in behavior or in mental functions; psychotechnologists- particularly psychiatrists, clinical psychologists, and educational psychologists; and the odd methodologist and philosopher capable of trading conceptual precision and deep questions for specialized scientific knowledge. Such an arrangement is likely to foster the integration of the many currently separate branches of psychology, and it would discourage the two extremes of excessive specialization and charlatanism, to the benefit of researchers, teachers, students, patients, and tax-payers.

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