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PSYCHOLOGY

PSYCHOLOGY. The term psychology first appears in the sixteenth century, denoting the study of the human soul (Greek psyche, 'soul'), a part of what was then called anthropology: the term is used thus in the first work to use it as a title, Rudolf Goclenius's Psychologia of 1594 (the title uses the Greek word). The term continued to be used in this way through the seventeenth century. Only in the early eighteenth century, with the publication of Christian Wolff's Psychologia Empirica (1732) and Psychologia Rationalis (1734), does it take on its modern sense, supplanting earlier terms like scientia de anima ('science of the soul'). The study of the soul, or the mind, did not, of course, begin in the eighteenth century. But it may, with some reason, be said to have begun again in the seventeenth.

ARISTOTELIANISM

From the mid-thirteenth century, when Aristotle's works became the basis of the baccalaureate curriculum in European universities, until the middle of the sixteenth, the starting point for the study of the soul was Aristotle's De anima. Hundreds of commentaries on it were published in the sixteenth and early seventeenth centuries. Often they included lengthy disputations on controversial topics, like the immortality of the soul and the nature of the rational soul. In the latter part of the sixteenth century the commentary form began to be abandoned in favor of the systematic textbook, of which Francisco Suárez's De Anima (1621; On the soul) is a noteworthy example. A reader of these works would have encountered the major ancient, Arab, and medieval interpretations of Aristotle and a fair helping of empirical observations, mostly from ancient authorities like Pliny and Galen, but also occasionally from such recent authors as Andreas Vesalius (1514–1564), whose De Humani Corporis Fabrica (1543) superseded the ancients on anatomical questions.

The subject matter of De Anima is life and the functions of life. Aristotle treats not only sensation, memory, imagination, and the intellect, but also what would now be thought of as purely physiological functions like digestion and reproduction. The task of the science of the soul is to define the soul itself and the functions proper to living things, to describe the organs and mixtures of elements that subserve them, and finally to establish the principles on which a classification of plants and animals is to be based.

The soul is what Aristotle calls a "form": it confers on matter the characteristics proper to a certain species of thing—the human, say. Medieval authors called the soul a "substantial form," substantial because like the body it is the bearer of properties. It is not the eye, Aristotle says, but the soul that sees. Every material substance, living or not, has a form; the soul is defined among material forms as that of "an organic body potentially having life." Certain functions are found only in the things we call living; the soul is the form proper to them. Although the soul requires a particular composition and configuration of matter to perform its functions, and some materials like blood and bile are found only in living things, neither the soul nor its functions can be reduced to mere mixtures or concatenations of nonliving stuffs.

The functions of living things were divided into three groups: vegetative, sensitive, and rational. All living things nourish themselves, grow, and reproduce. Animals, but not plants, have senses and can move about. Humans can do all that animals do; moreover, they can reason and exercise free will. The soul is accordingly divided into three parts. Only for the rational part, peculiar to humans, can it be argued that its operations do not require a material organ, and that therefore it can survive the dissolution of the body.

The predominant theory of sensation among Aristotelians was "species theory." Sensing consists in the reception of species (Latin species, 'aspect' or 'appearance') in the sense organ. Each sense has its own "proper sensibles"—there are species of color, sound, odor, and so forth. Species from the various senses are combined in the "common sense" (sensus communis) and then stored in memory (located in the ventricles of the brain), to be reactivated by recollection, imagination, or the "estimative power" (vis æstimativa), which performs such tasks as recognizing that a predator is dangerous, or that grass is food. In humans, sensible species undergo further refinement (the "abstraction from matter," for example, that Aristotle regards as characteristic of mathematics) and become "intelligible species," the raw materials used by reason.

CARTESIANISM

The consensus, never total, established around Aristotle broke down in the early seventeenth century. The stoutest blow was dealt to it by René Descartes (1596–1650). With his work the science of the soul begins to divide into two disciplines: a psychology of ideas and a physiology of the nervous system.

The notion of "idea" and the beginnings of an analysis of ideas are put forward in the Meditations (1640). In the Treatise of Man (written 1631–1633, published in Latin translation 1662), on the other hand, Descartes, following closely the plan of the relevant parts of De Anima, attempts to demonstrate that all the functions hitherto attributed to the souls of animals and plants could be exhaustively accounted for in purely mechanistic terms. The Description of the Human Body (1640s, first published in Latin translation 1662) extends that account to reproduction.

The body is for Descartes a hydraulic machine—a connected assemblage of organs whose actions are coordinated by the "animal spirits" (a fluid composed of subtle, fast-moving particles or "corpuscles") that course through the nerves and muscles. Seeing, for a cat, is a sequence of collisions of corpuscles, first of light particles on the nerve-endings in the retina and eventually of the animal spirits with the pineal gland, where they produce "impressions" that in a human body affect the mind to produce sensations of light and color. In human beings alone something more happens. The sight of a rose gives rise to a "mode" or modification of the soul, which for Descartes is a separate, immaterial substance "tightly joined" with the body. If by "seeing" one means 'having a visual sensation', then the cat does not see, only human beings do. Similarly, if "feeling pain" means 'having one's soul modified in the manner we call pain', then animals do not feel pain, only humans do. That consequence of Descartes's dualism excited much controversy from 1650 to 1750, as did the denial of souls to animals.

The human mind is unique. Insofar as psychology is the study of the soul, "animal psychology" is an oxymoron. Psychology comes to devote itself to the study of the operations of the human mind—its faculties and the ideas with which they operate. The essence of mind, according to Descartes, is to think. Occurrent thoughts are modes of res cogitans, the "thinking thing," and the "form" of such a mode is what Descartes calls an idea (see Hamilton, Dissertation G). That form can be described in terms of what the idea presents or represents to the mind. Ideas came to be thought of as akin to signs, "representing" concepts or things; whether Descartes and other early users of the term in its new sense regarded them thus is open to question (Yolton, 1984).

Cartesian psychology was not the only option in the seventeenth century. Pierre Gassendi's revival of Epicurean atomism contrasted both with the philosophy of the Schools and with that of his friend and rival Descartes. He retained the notion of an animal soul and considered the human soul to consist effectively of a material soul, similar to those of animals, and an immaterial rational soul (Bloch, p. 368), a view more closely resembling the Aristotelian than the Cartesian, in which the cognitive functions of the sensitive soul are elevated to become part of the single, immaterial human soul.

LOCKE AND THE "WAY OF IDEAS"

The Port-Royal Logic (1662) of Antoine Arnauld and Pierre Nicole placed ideas at the center of the study of thought. An idea is simply that which is "in our mind" when we conceive something. To the logical notions of term, proposition, syllogism, and method, there correspond the mental operations of conceiving (an idea), judging, reasoning, and putting arguments in order. Thus the study of language and thought were united into a new discipline at once concerned with the validity of arguments and the nature of the mind.

Cartesian physiology had failed conspicuously to live up to the promises made on its behalf by Descartes. Nicolaus Steno (Observations Anatomiae, 1662) and Thomas Willis (Cerebri Anatomae, 1664) had shown that Descartes's anatomy was grossly mistaken, and in particular that the pineal gland could not possibly have the functions he ascribed to it. Although anatomists in the early eighteenth century continued to map the brain and nervous system, and to make some headway in localizing functions, it is not surprising that philosophers should have taken to a method that did not require detailed knowledge of the "springs" of thought.

In Descartes's Rules for the Direction of the Mind (1626–1628, first published 1684), the "things" with which the philosopher deals are said to be simple or complex. That distinction, not entirely new, was applied to ideas: Arnauld and Nicole, and Leibniz shortly thereafter—both of them having access to the as yet unpublished rules—applied that distinction to ideas. Leibniz in particular is, in the 1670s, proposing the analysis of ideas into what he calls "primitive" ideas, not further analyzable. Locke's Essay concerning Human Understanding (1690) deals with the analysis of ideas, or the uncovering of the "original" ideas "from whence all the rest are derived" (p. 286). Those original ideas, few in number, Locke divides into ideas of sense, received from the body, and ideas of reflection, received from the mind.

The analysis and classification of ideas according to their composition from originals provided what could be called their "statics." The "dynamics" was based on the notion of the association of ideas. That one idea might call up another was not at all a new observation. Descartes had taken note of it, and Baruch Spinoza (1632–1677) adverted to it quite often. Locke's contribution was to make it fundamental to a theory of error. Not all connections among ideas arise from association. Some connections are natural (for example, between the idea of red and that of color). Some are artificial, forged by chance or custom, which can bind together any two ideas, however distant. Association became an important tool. George Berkeley (1685–1753), for example, explains depth perception by reference to a "habitual or customary" connection between the muscular sensations caused by positioning the eyes so as to maintain a single image of an object and the idea of the distance of that object from the viewer (Essay toward a New Theory of Vision, 1709).

Locke's Essay and the way of ideas were enormously influential through the eighteenth century. Condillac (Étienne Bonnot) in particular devoted his 1754 Traité des sensations (Treatise on sensations) to the study of a "statue" having only one of the five senses, and to the proposition that touch teaches vision how to recognize shapes and distances, the conclusion being that all the various faculties of the soul—judgment, reflection, the passions—are nothing other than "transformations" of sensation. (Destutt de Tracy, mentioned below, would later hold that all thought is feeling.) Condillac's claim that touch teaches vision was based in part on descriptions of the experiences of persons blind from birth who recovered their vision, including a famous case described by the London surgeon William Cheselden in 1728. That case seemed to provide an answer to William Molyneux's query to Locke, on whether a person blind from birth would recognize the objects previously known only by touch (see Degenaar).

David Hume (1711–1776) begins his Treatise (1739) with a distinction between "impressions" (unlike the impressions made by animal spirits on the pineal gland, these are in the mind) and "ideas," the difference being that impressions are, like Locke's "originals," not derived from other ideas. Ideas of substance and (most famously) cause are analyzed in terms of relations among ideas initiated by association (between resembling ideas) and confirmed into habit. The last concerted attempt to follow the way of ideas was the "ideology" of A. L. C. Destutt de Tracy, presented in his Idéologie of 1804. The political importance of Lockeanism is hinted at by noting that Destutt de Tracy was a deputy in the Estates General of 1789, who was arrested under the Terror but survived, and had his commentary on Montesquieu's Spirit of the Laws censored by the government of Napoleon in 1806.

MATERIALISM AND PANPSYCHISM

Eighteenth-century materialism was quite distinct from what is now called "physicalism." The physicalist holds that the only properties possessed by concrete substances are those imputed to them by established physical theory. The eighteenth-century materialist, in agreement with the physicalist, denies that the mind is immaterial, but typically sensibility (the basic mental property, as in Condillac and Destutt de Tracy) is treated as a property additional to the basic physical properties of matter, and not reducible to them.

Many eighteenth-century philosophers, among them Denis Diderot (1713–1784) and Pierre Louis Moreau de Maupertuis, attributed a primitive sensibility to small particles of matter, "organic molecules" as Georges Louis Leclerc Buffon called them, from which the more complex capacities of animals and humans are derived. Julien Offroy de La Mettrie is another instance. The title of his best-known work, first published in 1747 (with a false date of 1748), is L'homme machine (Man a machine), but in the machine every fiber is endowed with a natural oscillation, proved by, among many other experiments, the continued beating of the hearts of animals after they are removed (1751/1987, 1:104–105; see also L'homme plus que machine, 2:159). In the Rêve d'Alembert (1769; Dream of d'Alembert), Diderot, following the physician Théophile de Bordeu, likens the organism to a swarm of bees—the "organic molecules." Consciousness and will become "statistical" phenomena, like the changing sentiments of a crowd, a view reminiscent of certain much more recent theories of mental activity.

The end of the early modern period witnessed the discovery by Alessandro Volta (1745–1827) and Luigi Galvani (1737–1798) that nerves conduct electricity. That and the comparative studies of late eighteenth- and early nineteenth-century anatomists, which established, among other things, the independent role of the spinal cord in reflex actions, laid the basis for a neuroscience recognizably like that of today.

Willis, in his "Anatomy," writes that he "addicted my self to the opening of Heads especially, and of every kind" not only in order to found a "more certain Physiologie," but also a "Pathologie of the brain and nervous Stock" ("Anatomy," p. 53; quoted in Frank, p. 108). He went so far as to regard every disease as neural in origin; the resulting "neural pathology" had adherents even in the mid-nineteenth century. At the very end of the period, Philippe Pinel, famous for supposedly setting free the inmates of the Salpêtrière asylum in Paris during the Terror (Weiner, p. 333), published his Traitémédico-philosophique sur l'aliénation mentale (1801; Medico-philosophical treatise on mental alienation), one of the founding documents of the new discipline of psychiatry.

See also Aristotelianism; Berkeley, George; Cartesianism; Descartes, René; Gassendi, Pierre; Hume, David; La Mettrie, Julien Offroy de; Leibniz, Gottfried Wilhelm; Locke, John; Madness and Melancholy; Mechanism; Medicine; Spinoza, Baruch.

BIBLIOGRAPHY

Primary Sources

Bayle, Pierre. Dictionnaire historique et critique. 3rd ed. Rotterdam, 1720. 1st ed. Rotterdam, 1697.

La Mettrie, Julien Offroy de. Oeuvres philosophiques. 2 vol. Paris, 1987. 1st ed. London, 1751; L'homme machine and L'homme plus que machine were first published in 1748.

Locke, John. An Essay concerning Human Understanding. Edited by Peter H. Nidditch. Oxford, 1975. 1st ed. 1690.

Secondary Sources

Bloch, Olivier René. La philosophie de Gassendi: Nominalisme, matérialisme et métaphysique. The Hague, 1971.

Clarke, Edwin, and L. S. Jacyna. Nineteenth-Century Origins of Neuroscientific Concepts. Berkeley, 1987.

Degenaar, Marjolein. Molyneux's Problem: Three Centuries of Discussion on the Perception of Forms. Translated by Michael J. Collins. The Hague, 1996.

Hamilton, Sir William. "Editor's supplementary dissertations." In The Works of Thomas Reid, D. D., edited by Sir William Hamilton. 7th ed. Glasgow, 1872.

Porter, Roy. "Medical Science and Human Science in the Enlightenment." In Inventing Human Science: Eighteenth-Century Domains, edited by Christopher Fox, Roy Porter, Robert Wokler, pp. 53–87. Berkeley, 1995.

Roger, Jacques. The Life Sciences in Eighteenth-Century French Thought. Translated by Robert Ellrich. Stanford, 1998.

Rousseau, G. S., ed. The Languages of Psyche. Mind and Body in Enlightenment Thought: Clark Library Lectures, 1985–1986. Berkeley, 1990. See, in particular, Frank, Robert G., Jr. "Thomas Willis and His Circle: Brain and Mind in Seventeenth-Century Medicine" and Weiner, Dora B. "Mind and Body in the Clinic: Philippe Pinel, Alexander Crichton, Dominique Esquirol, and the Birth of Psychiatry."

Wellman, Kathleen Anne. La Mettrie: Medicine, Philosophy, and Enlightenment. Durham, 1992.

Yolton, John W. Perceptual Acquaintance: From Descartes to Reid. Minneapolis, 1984.

——. Thinking Matter: Materialism in Eighteenth-Century Britain. Minneapolis, 1983.

DENNIS DES CHENE