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René Descartes's philosophical importance for the advent of the modern scientific age is matched only by the difficulty of fully evaluating what his doctrines imply for religion. Born in Poitou, France, in 1596, Descartes lived most of his adult life in Holland, incurring the opposition, but also gaining the support, of Catholics and Protestants alike. He died in 1650 in Stockholm, where Queen Christina of Sweden had invited him to reside and instruct her in philosophy.

In his lifetime, he published works in both French and Latin, aimed at two slightly different audiences: Discourse on the Method of Rightly Conducting Reason and Reaching the Truth in the Sciences (French, 1637), Meditations on First Philosophy (Latin, 1641), Principles of Philosophy (Latin, 1644), and Passions of the Soul (French, 1649). Descartes also left unfinished works, notably Rules for the Direction of the Mind (Latin), The Search for Truth (Latin), The Universe or Treatise on Light (French), and Treatise on Man (French), as well as a voluminous correspondence in both French and Latin.

Method and faith

As a boy, Descartes attended the Jesuit College of La Flèche. Recalling his education in Discourse on the Method, Descartes denounces bookish learning and the vain pretense of scholastic philosophy, but favorably cites his love of poetry, his delight in mathematics, and his reverence for "our" theology. He emphasizes being firmly taught that revealed truths are above human intelligence. Stating moreover that the truths of faith have "always been first" in his beliefs, he explicitly says that these truths must be "set apart" from human opinions and must not be subjected to his method of universal doubt. Descartes consistently maintains this position throughout his work, from the early and unpublished Rules for the Direction of the Mind to the mature Principles of Philosophy, where article seventy-six gives divine authority unambiguous precedence over human reason. Youthful diaries dating from his years of wandering and soldiering (1618–1620) reveal a feverish, unconventional, religious imagination, coupled with devout impulses.

A critical aspect of Descartes's mature philosophy for issues of science and religion is that his theory of mind (res cogitans) explicitly privileges free will over cognition. During an extended stay in Paris from 1620 to 1627, Descartes had frequent exchanges with leading religious figures: Marin Mersenne (1588–1648), who was also educated at La Flèche; Guillaume Gibieuf, a priest of the Oratory busy writing a book on freedom of the will; and Cardinal Pierre de Bérulle, who encouraged Descartes to pursue his reform of philosophy as a duty and vocation. In Rules for the Direction of the Mind, composed in the immediate wake of these meetings, Descartes affirms that revealed truths are held with even greater certainly than natural truths since "faith rests, not on an act of intelligence, but an act of will." He also distinguishes between cognition as such and the faculty of "affirming and denying" in an attempt to explain error, but the second faculty is not yet clearly identified with the free will, as it will be in the Meditations (1641) and in article thirty-two of the Principles of Philosophy (1644).

In 1628, Descartes moved to Holland in search of solitude. A letter to Mersenne dated April 15, 1630, reveals the extent to which physics and metaphysics were indivisibly combined in this search. Descartes explains that he would not have discovered the foundations of physics if he had not started with the rational discovery of self and God, which is indeed everyone's "first duty." God, Descartes maintains further, is "the first and most eternal" truth from which "all other truths proceed." Most dramatically, Descartes affirms that eternal truths are created: God has freely decreed that two and two make four, so that mathematical truths "depend on God's will no less than creatures." By 1630, while solving problems of mechanics and conducting dissections in his home, Descartes thus conceptualized divine freedom, the new physics, human self-knowledge, and dependence on God as intricately connected.

Cartesian naturalism

When Descartes learned of Galileo's condemnation in 1633, he cancelled plans to publish the cosmological Universe or Treatise on Light designed to unveil his new philosophy, citing at a later date "those whose authority has hardly less power over my action than my own reason over my thoughts." Instead, he published the Discourse on the Method anonymously in Leiden in 1637, along with "samples" of what his new method could achieve in geometry, optics and meteorology. Presenting his proof of self and God as pivotal to his own intellectual awakening, Descartes launches a framework in which physical phenomena, including biological phenomena, can be investigated experimentally according to materialist principles, while special mental events exhibiting voluntary features and characteristic of human beings are set apart and assigned to a distinct immaterial principle. In the Discourse, Descartes proceeds naturalistically in so far as he cites the empirical evidence of languages to conclude that the human "rational soul" is "in no way drawn from the potentiality of matter" and is therefore "not liable" to die with the body.

Cogito and freedom

Objections from all sides greeted Descartes's radical move to explain biological phenomena by means of inert microcorpuscular processes, as well as Descartes's bold noetic proof of self ("I think, therefore I am") and God. In 1639, desirous to clarify his views and to answer his critics, Descartes began writing his masterpiece, Meditations on First Philosophy, published in Paris in 1641. Composed in Latin, the text of the Meditations is followed by objections and answers, and is dedicated to Paris theologians. This time, the reader is led through a six-day journey of introspection and analysis designed to purge the mind of naïve empiricism, secure new grounds of noetic truth by rooting the human soul in God, and promote scientific investigation of the material universe (res extensa) as a way to cultivate personal happiness while working for the common good. From the demonic ordeal of the first day to the orderly reintegration of soul and body on the last, Descartes's core concern is to champion the inalienable gift of freedom that marks human beings as created in God's image. God, Descartes explains, has "left it in my power not to err" since he is always free to suspend judgment when evidence is insufficient. No evil demon, however powerful, can compel him to affirm as true what is merely doubtful. Human freedom thus manifests the will's inherent predilection for what is good and true, even in the absence of any known good or truth. Moreover, clarification in Meditation VI that the senses are meant for immediate survival and must therefore not usurp the function of reason in proposing to our freedom truths to be affirmed allows the same responsible exercise of judgment afforded by geometry to extend to the physical and experimental sciences.

The moral value of the scientific project thus lies primarily in the special opportunity it provides for deliberately searching out and affirming the truths that God has freely decreed. Significantly, in the Principles of Philosophy, charmingly dedicated to his favorite pupil Elizabeth of Bohemia, the principle of human freedom (article six) precedes the principle of cognitive certainty or cogito (article seven): The freedom to abstain from error is even more fundamental than the first cognitive certainty I think; I am. And as article thirty-seven goes on to explain, a human being's principle perfection lies in having a free will, and people act worthily whenever they deliberately choose what is true.

Further development of Descartes's views relating to proper use of the free will, truth, and human happiness, is found in Descartes's numerous letters to Elizabeth, and in the treatise on The Passions of the Soul, published in 1649. Descartes distinguishes between autonomous acts of will that terminate in bodily actions and those that terminate "in the soul itself, as for example, when we resolve to love God, or more generally, apply our thought to some immaterial object." Acts of the will that are based on false opinions leave one vulnerable to regret and remorse, while those that are securely based on knowledge of the truth lead instead to happiness and inner serenity. Descartes's letter to Queen Christina dated November 20, 1647, may serve to summarize Descartes's integration of religion and science since he declares that the highest good, for each and every human being, consists in "a firm will to do what is good and in the serenity to which this leads."

Influence

Although what is crudely described as Cartesian dualism has been mostly rejected by later philosophy, the problem of human freedom raised by Descartes and explained by him on the basis of a distinct, substantial, and immaterial spiritual principle (res cogitans), has be no means disappeared. The linguist Noam Chomsky has repeatedly drawn attention to some of the advantages of Cartesian rationalism for the defense of universal human dignity. In France, the philosopher Nicolas Grimaldi continues to emphasize the relevance of Cartesian freedom, while Jean-Luc Marion has in turn used Descartes as a springboard to elaborate new perspective on ethics. Most importantly, Cartesian scholars continue to discover seminal ideas in Descartes regarding the spiritual dimension of science. Daniel Garber, in particular, has shed light on the distinctive metaphysical features of Cartesian physics; Gary Hatfield has called attention to the deeply religious character of Descartes's notion of force; and Matthew Jones has initiated new questions on the spiritual dimension of Descartes's mathematics.

See also CARTESIANISM; FREEDOM; MODERNITY

ANNE A. DAVENPORT