Cartesianism

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Cartesianism was a set of philosophical theses, a scientific program, and a broad intellectual movement that dominated the European scene in the seventeenth century. The foremost philosophical paradigm of the period, it was the subject of passionate debate and strong opposition both within the universities and in society at large.

The philosophical theses of Cartesianism have their origins in the thought of René Descartes (1596–1650), who first sought in a systematic manner to replace the dominant Aristotelian philosophy of the Schools with a new philosophy, one wedded not to conformity with some ancient or medieval thinkers or a particular religious tradition but to a rationally justified confidence in our own natural cognitive faculties. The new philosophy would liberate society from unreflective obedience to authority, prejudice, and philosophical (and maybe even theological) dogma and contribute to scientific and social progress—not to mention material well-being—by advancing our understanding of nature and the universe

The most prominent and perhaps defining thesis of the Cartesian philosophy is what has come to be called "mind-body dualism." Descartes insisted on the real distinction between mind and matter. Mind (or soul) and matter (or body) are, according to Descartes, two essentially and radically different kinds of substance. Mind is unextended, indivisible, simple thinking. Its modes or properties are particular ideas or thoughts including beliefs, volitions, sensations, and emotions. Matter, on the other hand, is nothing but extension or dimensional space and is therefore divisible, its modes being shape, size, and mobility. There is nothing materialistic about the mind and nothing mental or spiritual about the body.

This doctrine is of great importance not only for understanding the nature of the human being, who is a composite—or, to use Descartes's phrase, a "substantial union"—of these two substances, but also for science. According to Descartes, the physical world is nothing but passive matter or extension, divisible ad infinitum into parts. This was, he believed, a great advance over the Aristotelian world picture. The spiritlike forms and qualities that were used by the Scholastics to explain the behaviors of physical bodies have been banished from nature. All natural phenomena, no matter how complex and regardless of whether they are terrestrial or celestial, are henceforth to be explained solely in terms of matter and the motion, rest, and impact of its parts. Descartes's separation of mind and matter was a crucial step in the scientific revolution of the seventeenth century, and laid the metaphysical foundations for the mechanical philosophy that dominated the period until Newton. (Descartes also believed, at least as a matter of public record, that dualism offered the strongest possible foundation for the doctrine of the immortality of the soul, since the mind as a simple, thinking substance was not subject to the process of decay and destruction that brought about the demise of complex and divisible bodies.)

Descartes's philosophy bequeathed to his many devoted followers a host of difficult philosophical (and theological) problems. If mind and body are so radically different in nature, how do they causally engage one another and interact in the way they seem to do in a human being? If matter is nothing but inert, passive extension, what explains the motion, interaction, and dynamic behavior of bodies? Moreover, Descartes believed that, since matter is pure extension, body is not distinct from space, and a truly empty space (or vacuum) is therefore impossible in nature; the universe is a material plenum. How, then, does there arise a multiplicity of individual bodies, and how is their motion possible? Most distressing to religious authorities—and one of the issues that led to Descartes's works being placed by the Catholic Church on the Index of Prohibited Books in 1663—were the apparent consequences of Descartes's metaphysics for the Catholic dogma of the Eucharist. If any particular body (such as a piece of bread) is just a specific parcel of extension and there are no "real qualities" that are distinct and separable from an underlying substance, how can the Cartesian philosophy account for the miracle of transubstantiation? According to the traditional Aristotelian account adopted by the Church, at the moment of consecration the sensible qualities of the bread remain while its substance is replaced by the substance of Christ's body. Descartes has done away with such qualities, and a body is now just its extension; if the substance of Christ's body takes on the extended dimensions of bread, then, according to Descartes's metaphysics of body, it is just bread.

The first generation of Cartesians included men like Henricus Regius (1598–1679), Johannes de Raey (1672–1702), and Adriaan Heereboord (1614–1661). These Dutch academics' introduction of Cartesian principles into their university courses in medicine, physics, and even theology incited a bitter backlash from the authorities. The new philosophy was perceived as a threat to the established (Aristotelian) order. The Reformed theologian and rector of the University of Utrecht, Gibertus Voetius (1589–1676), was only the most outspoken and determined of Descartes's numerous foes, and his institution was the first among many to issue condemnations of Cartesian philosophy and to prohibit its teaching. The controversy over Cartesianism in the Netherlands raged not only in the academy, but in the broader intellectual culture as well. It spilled over into the social and political realm and became enmeshed in the battles that deeply divided factions of the Reformed Church and opposing political camps of the Republic.

In France, the Saumur physician Louis de la Forge (1632–1666), one of Descartes's early and most faithful followers, produced an illustrated and annotated edition of Descartes's Treatise on Man, a work on the physiology of the human body, and supplemented it with his own Treatise on Man's Soul (1666), in which he explains, on strict Cartesian principles, the workings of the human mind and its relationship to the body. La Forge recognized some of the metaphysical problems inherent in Cartesian dualism and the physics of extended bodies and was among the first to defend a limited version of the doctrine called "occasionalism." According to La Forge, the motion of extended bodies, which are intrinsically passive, is explained by the causal activity of God. The moving force of a body in motion is nothing but the divine will, which moves the body by recreating it in a different relative place from one moment to the next. Another occasionalist Cartesian, somewhat less orthodox in his fealty to Descartes than La Forge, was the Parisian lawyer Géraud de Cordemoy (1626–1684), who insisted—contrary to Descartes, for whom any parcel of extension, no matter how small, was in principle divisible—that there were atoms, or ultimately indivisible parts, in nature. The Dominican friar Robert Desgabets (1610–1678) pursued his own Cartesian program in the realm of theology and offered suggestions as to how to reconcile Descartes's metaphysics with the Eucharistic doctrine of "real presence." The physicists Jacques Rohault (1620–1672) and Pierre-Sylvain Régis (1632–1707) sought the mechanistic explanations of natural phenomena, experimentally verified, in an attempt to complete those particular and more detailed aspects of physics that Descartes left open.

While united by their adherence to a broad philosophical program, these Cartesians did not constitute an organized group but worked independently to further what they saw as the right and progressive philosophy. By far the most important Cartesian of the seventeenth century, however, was a French Oratorian named Nicolas Malebranche (1638–1715). A bolder and more systematic thinker than the others, Malebranche was not afraid to modify and even depart from Descartes's ideas in highly unorthodox ways. His occasionalism was thoroughgoing: God is the only real causal agent in the universe. All finite things are created and sustained in being by God, and all events, whether mental or physical, are brought about by the divine will. Creatures and their states are only secondary causes, or "occasions," for God to exercise genuine power. Malebranche also argued that the clear and distinct ideas that serve as the objects of human intellectual understanding are not modes or properties of the human mind but rather ideal archetypes in the divine understanding. With his theory of the Vision in God Malebranche sought to make human beings as dependent upon God for their knowledge as all creatures are dependent upon God for their being and activity. His doctrines were attacked by other Cartesians, most notably the Jansenist fire-brand Antoine Arnauld (1612–1694), who thought Malebranche's ideas represented not only an unacceptable departure from the true principles of Descartes's philosophy, but also a serious threat to Christian faith.

By the third quarter of the century, Cartesianism, while vigorously condemned by leading religious and political authorities (in 1667 the French court prohibited a public funeral oration from being delivered at the ceremony for the reburial of his remains in Paris), enjoyed immense success. Nonetheless, it suffered from serious internal weaknesses and obvious explanatory failures. The advent of Newtonianism at the end of the century, with its alternative conception of scientific understanding, powerful mathematical presentation, and explicit critique of Cartesianism, brought about the final downfall of this formidable scientific paradigm.

Bibliography

Des Chene, Dennis. Physiologia: Natural Philosophy in Late Aristotelian and Cartesian Thought. Ithaca, N.Y., 1996.

Garber, Daniel. Descartes's Metaphysical Physics. Chicago, 1992.

Nadler, Steven M., ed. The Cambridge Companion to Malebranche. Cambridge, U.K., and New York, 2000.

Schmaltz, Tad M. Radical Cartesianism: The French Reception of Descartes. Cambridge, U.K., and New York, 2002.

Watson, Richard A. The Breakdown of Cartesian Metaphysics. Atlantic Highlands, N.J., 1987.

—STEVEN NADLER