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Darwin

And The Emergence of Evolutionary Theories of Mind and Behavior

The University of Chicago Press

Origins of Evolutionary Biology of Behavior

The sciences of ethology and sociobiology have as premises that certain dispositions and behavioral patterns have evolved with species and that the acts of individual animals and men must therefore be viewed in light of innate determinants. These ideas are much older than the now burgeoning disciplines of the biology of behavior. Their elements were fused in the early constructions of evolutionary theory, and they became integral parts of the developing conception of species transformation. Historians, however, have usually neglected close examination of the role behavior has played in the rise of evolutionary thought.

Yet behavior has been an important consideration virtually from the beginnings of systematic biological theorizing. Aristotle devoted generous portions of his Historia animalium to discussion of species-typical habits and relative grades of animal intelligence. Galen conducted a set of elegant experiments to show that certain actions of animals were innate and not learned. In the seventeenth and eighteenth centuries, naturalists often disputed violently over interpretations of animal behavior, contending whether the activities of brutes were to be regarded as congenitally fixed or as the consequences of reasoned choice. These debates formed the immediate environment for the emergence of evolutionary theories at the turn of the eighteenth century. In this chapter, I wish to focus on the problems that animal instinct and intelligence posed for early evolutionary theorists. A chief difficulty stemmed from their commitment to the doctrines of sensationalism. Adherents of this persuasion in the seventeenth and eighteenth centuries generally argued that all ideas merely imaged sensations and that rational behavior, of which even animals were capable, derived from habitually associated ideas. Sensationalists thus tended to deny the existence of innate and mechanically expressed instincts, the most likely candidates for evolutionary treatment. My intention here is to explain how evolutionists accommodated to sensationalist doctrine the conviction that behavior did evolve. For this purpose, I will examine the roles of instinct, intelligence, reason, and particularly the mediating construct of habit in the theories of four early evolutionists: Erasmus Darwin (1731–1802), Pierre-Jean Cabanis (1757–1808), Jean-Baptiste de Lamarck (1744–1829), and Frédéric Cuvier (1773–1838). Since I hold scientific theories to be analogous to evolving biological species, I will emphasize the conceptual legacies inherited by these early thinkers, the intellectual and cultural environments that shaped their ideas, and the competitive reactions they evoked from rivals.

Let me briefly indicate some of the conclusions toward which this chapter arches. The history examined reveals, I believe, that evolutionary ideas developed in response, not only to narrowly conceived problems in zoology, but also to critical difficulties in the epistemological, psychological, and social-political doctrines of sensationalism. More specifically, it makes clear the central importance of conceptions of habit, instinct, intelligence, and reason for the first formulations of evolutionary principles. Finally, it shows that behavior was originally regarded, not merely as an outcome of the evolutionary process, but also as its principal agent.

Controversies over Animal Instinct and Intelligence in the Seventeenth and Eighteenth Centuries

Aristotelians, Cartesians, and Sensationalists

During the seventeenth and eighteenth centuries, disputes over the nature and capacities of human mind were frequently waged on foreign territory—in the field of animal psychology. Fresh evidence from natural history, whose practitioners increased in number during the period, was brought to bear on metaphysical and epistemological issues. This new evidence, however, did not so much test ideas in contention as open the battle on another front. The disputants grouped themselves into three camps, within which, of course, factional differences often arose. The Aristotelians distinguished the human soul, with its rational abilities, from the animal soul, which could be guided only by sensory cognition. The Cartesians also separated man from animals, though more decisively. For Descartes and his disciples, animals mimicked intelligent action, but operated as mere machines: brutes consisted of extended matter alone and functioned according to the laws of physics. Finally, the sensationalists (who adopted the basic tenets of Locke's epistemology) held that human knowing drew exclusively on the same resources available to animals—sensations. The epistemology of sensationalism seemed to be confirmed by the successes of experimental methods in the various sciences and technologies; but toward the end of the eighteenth century, careful observations of animal behavior began to undermine the assumptions of sensationalist epistemology. Naturalists committed to sensationalism thus faced a critical problem, which had implications for their conception not only of animal psychology, but of human psychology as well. The disputes over animal abilities and the dilemma confronted by sensationalists centered on the problems of brute instinct and intelligence.

Aristotelians and Cartesians differed profoundly on the ultimate principles of animal psychology. They nonetheless agreed that complex animal behavior (e.g., birds' building their nests and bees' their cells) should be explained by appeal to instincts, which they understood as blind, innate urges instilled by the Creator for the welfare of his creatures. Pierre Gassendi (1592–1655) forcefully opposed this interpretation of animal behavior. In his Syntagma philosophicum (posthumous, 1658), he undertook a comparative study of animal and human cognitive abilities and discovered they were logically similar: both human and animal souls operated on sensory images to yield reasoned actions. Marin Cureau de La Chambre (1594–1669), an associate of Gassendi, concurred in his friend's conclusions; and through the next century French sensationalists continued to be chary of the use of instinct in the account of animal behavior. The attitude of Jean-Antoine Guer (1713–1764), a historian of animal psychology writing in mid-century, is representative. Guer believed the ascription of instinct to animals confounded any real attempt at scientific explanation, for "nothing is easier to say about whatever animals do than they do it from instinct." Rather than attempt to uncover the reasons for animal activities, the Aristotelians, according to Guer, invoked the myth of substantial forms (in the guise of brute souls), which were to serve as repositories for instincts that supposedly predetermined behavior. Guer held Descartes and his disciples in no higher regard. The Cartesians refused beasts even the low-level, sensitive cognition granted by Aristotelians. Instead, they presumed all animal behavior to tick off like a clock. Guer delighted in this absurdity of Cartesian animal psychology: "Take your dog. Let us wind up that clock and set it, say, for six o'clock; that is, let us suppose a certain disposition in the organs of the animal, a certain arrangement, a certain sort of heat in its heart and stomach. Behold, the clock runs!" The Cartesian beast machine, by sensationalists' lights, could be neither living beast nor preset machine. It was not truly an animal, since animals obviously did perceive, feel, and act intelligently, nor a machine, since Cartesian matter lacked any active principles that could explain these qualities.

Sensationalists easily exploited the dilemma of the Cartesians, who wished to explain behavior on simple, natural principles and yet to capture the complexities it revealed. The Abbé de Condillac (1715–1780), for instance, found an exemplar of this Cartesian problem in the theory of animal automatism formulated by the great natural historian Georges Leclerc, Comte de Buffon (1707–1788) in his Histoire naturelle (1749–1804). Condillac pointed out that Buffon's insistence that animals were unthinking, instinctive machines clashed with his attribution to them of perception and feelings of pleasure and pain. In Condillac's sensationalist epistemology, such predications implied that a creature could think and make rational determinations, which were merely the results of complex associations of sensory images.

The sensationalists resolved the Cartesian dilemma by reformulating both physical and psychological theory. First, they admitted that animals—and men—were machines, though not composed of inert matter. Thus Julien Offray de La Mettrie's (1709–1751) L'homme machine (1748) did not merely extend a Cartesian mechanistic analysis to the human mind, but reconstructed the very idea of matter. According to La Mettrie, matter harbored active properties of motion and sensation, which were expressed when it became organized in living beings. This new conception of matter allowed La Mettrie and other sensationalists to refer intricate and complex behaviors to a medium plastic enough to produce them, but these thinkers could still maintain the ideal of simple, natural principles of explanation.

The sensationalists also introduced important epistemological and psychological reformations to the account of animal behavior. They argued that ideas were only copies of impressions received by sensory machines. Rational intelligence, they claimed, was not the product of an immaterial mind but of refined habit and complex processes of sensory association. Animals, then, might entertain ideas, which were more or less detailed representations of their environments. Through memory and imaginative associations, their behavior could thus be guided by reasonable considerations. Condillac insisted that a careful examination of animal activities would discover, contrary to Cartesian opinion, that supposedly blind instincts were really intelligently acquired habits. Therefore we should not, his expositor Le Roy declared in the Encyclopédie, use "instinct" to refer to animal behavior "except that that word becomes synonymous with 'intelligence.'"

Though Charles-Georges Le Roy (1723–1789) affirmed Condillac's sensationalist interpretation of animal action in the Encyclopédie, he remained a bit more conservative in his own diagnoses of mammalian behavior. In his Lettres sur les animaux (1768), a work later admired by Charles Darwin, Le Roy traced the development of intelligence in young wolves, foxes, and deer against the background of their social and natural circumstances. In his analyses, he preserved the notion of instinct to refer to basic, physiologically determined desires—the need for certain foods, shelter, and acceptable climate. But he refused instinct any role in directing behavior designed to satisfy those needs. He rather believed this was accomplished by sensory experience and the applications of wakening intelligence.

To argue successfully that individual intelligence shaped animal behavior, the sensationalists had to deny that innate images, which many instinct theorists postulated, played any role in guiding actions. Connate images, though, were not so much argued against as simply dismissed as repugnant to the accepted Lockean conviction that all ideas ultimately derived from sense experience. This same epistemological tenet also weakened the support for a common feature of traditional theories of instinct, the assumption that instinctive activities were rigidly uniform in a particular species. For instance, René-Antoine de Réaumur (1683–1757), who detected the stirrings of intelligence even among insects, protested the Cartesians' presumption of machinelike, predetermined fixity in the conduct of animals. His objection conformed to the sensationalists' insistence that ideas (including those directing behavior) were not universals but particulars, fainter copies of sensations. Particular ideas could well account for variability in animal activity. And uniformity of action displayed by members of the same species could be attributed, according to Condillac and Le Roy, to the community of fundamental needs and the similarity of environments in which the young were reared. There was no cause to postulate of animals innate, universal ideas to explain their behavior.

Social Implications of Sensationalism

An evolutionary model of scientific change recommends that the historian assess the complex environments against which scientific ideas were selected. The various overlapping intellectual ecologies for ideas about the evolution of behavior consisted of theological, metaphysical, psychological, and epistemological conceptions, aspects of which I have already touched on. I wish now, rather briefly, to consider how certain social views gave support to one strain of development—that culminating in Cabanis's behavioral evolutionism. In a moment, I will indicate how a related set of social and professional constraints forced the convergence of Erasmus Darwin's biopsychological thought with that of Cabanis and Lamarck.

Sensationalist psychological theory supported the social doctrines of Enlightenment thinkers, particularly the French philosophes and ideologues. Jean d'Alembert (1717–1783), in his Discours préliminaire (1751) to the Encyclopédie, explained that refined sensory experience naturally generated those clear ideas that lay at the foundation of exact science. He attempted to demonstrate this by tracing the progressive development of scientific knowledge from the first experiential generalizations of early men to the accomplishments recorded in the Encyclopédie The editors of that massive work, of which d'Alembert was one, regarded its volumes as the repository of scientific and technical achievements grounded in direct observation and practice. They believed that steady application of the principles derived from these sources promised continued development of socially useful innovations. D'Alembert's younger colleague, the Marquis de Condorcet (1743–1794), also uncovered the roots of scientific progress in the psychological ability of men to receive and compare sensations, to order them by means of signs, and to use them in various combinations. In his unfinished Esquisse d'un tableau historique des progrès de l'esprit humain (1795), Condorcet sought to demonstrate historically how the rational analysis of society, based on the methods of advancing science, had begun to release men from the tyranny of both nature and their own superstitions and to disclose a future of material and social progress.

During the Revolution, Condorcet's progressive social views could not disguise his noble lineage. He was hidden from the Terror by his ideologue friend, the physician Pierre-Jean Cabanis, who shared his conviction that the empirical sciences, especially medicine, might continue to promote social progress. Cabanis based his program for the moral use of medicine on his belief that ideas, from the most speculative to those guiding practice, bubbled up from sensations, and thus became subject to all the physical influences that operated on the external and internal organs of sense. Medicine, then, might aspire "to perfect human nature generally." Cabanis held out this hope in his Rapports du physique et du moral de l'homme (1802):

Without doubt, it is possible, by a plan of life, wisely conceived and faithfully followed, to alter the very habits of our constitution to an appreciable degree. It is thus possible to improve the particular nature of each individual; and this goal, so worthy of the attention of moralists and philanthropists, requires that all the discoveries of the physiologist and physician be considered. But if we are able usefully to modify each temperament, one at a time, then we can influence, extensively and profoundly, the character of the species, and can produce an effect, systematically and continuously, on succeeding generations.

Cabanis found empirical support for his plan of perfecting the human species in the experience of stockbreeders, who demonstrated effective natural methods for racial improvements. His theoretical support lay in the animal psychology worked out by La Mettrie, Condillac, Le Roy, and similarly disposed sensationalists.

Thus for instance Le Roy, in his investigations of the psychological growth of young animals in their natural environments, isolated those social factors that led to the improvement or retardation of their intellectual faculties. La Mettrie showed that adoption of sensationalist epistemology led to the presumption that so-called inferior creatures might be improved, if given the same social advantages as enjoyed by men. So an orangutan, if taught to communicate by using techniques designed for the deaf, might "no longer be a wild man, nor a defective man; he would be a perfect man, a little gentleman, with as much substance or muscle as we have for thinking and profiting from his education." La Mettrie, like Cabanis who read him, intended not only to demonstrate psychological continuity between men and animals, but also to use evidence of the connection to argue that moral and social progress could be promoted by controlling the physical sources of and influences on intellectual faculties.

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Excerpted from Darwin by Robert J. Richards, David L. Hull. Copyright © 1987 The University of Chicago. Excerpted by permission of The University of Chicago Press.
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