In the Regulae, in first part of Rule XII, Descartes characterizes “ideas” in terms of “figures” or “shapes” formed in the imagination (AT X 414: CSM I 41), thus reworking in a fairly precise, if critical, fashion the doctrines of Aristotle's De Anima. But in the second part of Rule XII, he abandons this seemingly cautious use of the traditional framework, and introduces an utterly new concept, that of the “simple nature” (natura simplicissima; res simplex). This is not only, or primarily, a terminological innovation; what is involved is an epistemological revolution.

A simple nature has two characteristic features: it is neither simple, nor a nature. It is, first of all, opposed to "nature," since in place of the thing considered in itself, according to its ousia (essence), or physis (nature), it denotes the thing considered in respect of our knowledge: "when we consider things in the order that corresponds to our knowledge of them (in ordine ad cognitionem nostram) our view of them must be different from what it would be if it were speaking of them in accordance with how they exist in reality" (AT X 418: CSM 144).

Descartes understood the subject matter of physics to encompass the whole of nature, including living things. It therefore comprised not only nonvital phenomena, including those we would now denominate as physical, chemical, minerological, magnetic, and atmospheric; it also extended to the world of plants and animals, including the human animal (with the exception of those aspects of human psychology that Descartes assigned solely to thinking substance). In the 1630s and 1640s Descartes formulated extensive accounts of the principal manifestations of animal life, including reproduction, growth, nutrition, the circulation of the blood, and especially sense induced motion. In connection with the latter he discussed at length the bodily conditions for psychological phenomena, including sense perception, imagination, memory, and the passions. He also examined the mental aspects of these phenomena, sometimes by way of complementing his physiological discussions and sometimes as part of his investigation into the grounds of human knowledge.

At the height of his enthusiasm for Locke, Voltaire delivered a characteristically witty verdict on his great compatriot:

THE ROLE OF GOD IN DESCARTES' SYSTEM

There is a paradox at the heart of Cartesian metaphysics. On the one hand, Descartes' whole system of scientific knowledge depends on our assured knowledge of God; but on the other hand, the idea of God is explicitly stated by Descartes to be beyond our comprehension. This paradox emerges in Descartes' proofs of God's existence, and hinges on the relationship between the affirmation of God's existence and the elucidation of the idea of God, which is the basis for that affirmation. The relationship is difficult to explicate precisely: is the idea of God prior to the demonstration of his existence?

All the proofs Descartes offers of God’s existence, whether a priori or a posteriori, make use of the idea of God. And we are told that "according to the laws of true logic, one must never ask if something exists [an sit] without knowing beforehand what it is [quid sit]" (AT VII 107-8: CSM II 78); in the absence of such prior knowledge, we could not identify as God the being whose existence we are demonstrating. The idea of God would thus appear to be a necessary premise for all the proofs of his existence, and this clearly implies that we must possess within us the relevant idea in order to be able to infer that its object or ideatum really exists outside our minds.

Throughout his life Descartes firmly believed that the mind, or soul, of man (he made no distinction between the two terms) was essentially nonphysical. In his earliest major work, the Regulae (c.1628), he declared that “the power through which we know things in the strict sense is purely spiritual, and is no less distinct from the whole body than blood is distinct from bone, or the hand from the eye” (AT X 415: CSM I 42). In his last work, the Passions de l'dme (1649), he observed that the soul, although 'joined' or 'united' to the “whole assemblage of bodily organs” during life, is “of such a nature that it has no relation to extension, or to the dimensions or other properties of the matter of which the body is composed” (AT XI 351: CSM I 339). And between these chronological extremes we have the central claim of the Meditations (1641): there is a 'real' [realis) distinction between the mind and body, - in other words, the mind is a distinct and independent 'thing' (res). The thinking thing that is 'me' is “really distinct from the body and can exist without it” (AT VII 78: CSM II 54).

Descartes is perhaps the most widely studied of all the great philosophers. Students in countless introductory courses find that their imagination is captured by the lonely quest for knowledge described in Descartes' masterpiece, the Meditations on First Philosophy. The radical critique of preconceived opinions or prejudices (praejudicia) which begins that work seems to symbolize the very essence of philosophical inquiry. And the task of finding secure foundations for human knowledge, a reliable basis for science and ethics, encapsulates, for many, what makes philosophy worth doing. The excitement felt on first encountering Cartesian philosophy does not diminish as one delves deeper. Descartes' inquiries into the nature and structure of the material universe, his views on human freedom and the existence of God, and his account of the human condition and the relationship between mind and matter, all exert a powerful intellectual pull on us even today. And even when the details of the system are forgotten, Descartes' starting point in the quest for truth, his Cogito ergo sum (“I am thinking, therefore I exist ”) remains the most celebrated philosophical dictum of all time.

THE TRUTH RULE AND THE PROBLEM OF THE CARTESIAN CIRCLE

Descartes writes in the second paragraph of the Third Meditation: “So I now seem to be able to lay it down as a general rule that whatever I perceive very clearly and distinctly is true ” (AT VII 35: CSM II 24). I call this principle the truth rule. In the third paragraph, Descartes decides that it is premature to take the truth rule to be established. He writes of “very simple and straightforward” propositions in arithmetic and geometry: “the . . . reason for my . . . judgment that they were open to doubt was that it occurred to me that perhaps some God could have given me a nature such that I was deceived even in matters which seemed most evident” (AT VII 36: CSM II 25). The matters that seem most evident, in the context of paragraph two, are beliefs based on clear and distinct perception, so that these beliefs (together with any that seem less evident) are themselves open to doubt. Descartes writes: “in order to remove . . . this . . . reason for doubt, . . . I must examine whether there is a God, and, if there is, whether he can be a deceiver” (AT VII 36: CSM II25). In the Third Meditation, Descartes offers an argument for the existence of a nondeceiving God. The truth rule is finally proved in the Fourth Meditation. Descartes concludes, on the ground that God is no deceiver, that “if . . . I restrain my will so that it extends to what the intellect clearly and distinctly reveals, and no further, then it is quite impossible for me to go wrong” (AT VII 62: CSM II 43).

No one contributed more to the early development of algebra than Descartes. In particular, he was able to unify arithmetic and geometry to a significant extent, by showing their mutual connections in terms of an algebraic notation. This was an achievement that eclipsed his other scientific work, and Descartes believed that algebra could serve as a model for his other enterprises. The connection between algebra and his other scientific work was explored, via a consideration of the question of method, in Descartes' first published work, the Discourse on the Method of rightly conducting one's reason and seeking the truth in the sciences, together with the Optics, the Meteorology and the Geometry which are essays in this method (1637). What we are ostensibly presented with here is a general treatise on method, to which are appended three examples of the method.

What difference, if any, does the specific character of an individual's body make to the way that individual thinks, to his thoughts and to the sequence or association of his thoughts? What must the body be like, so that its contribution to thinking is reliable, and perhaps even useful? What nonepistemic benefits does the body bring to the mind? Although Descartes did not himself ask these questions in just these terms, answering them is central to the success of his enterprise. In any case, he provided the materials for addressing those issues, which he would have formulated as a problem about how divine epistemic benevolence - a guarantee of the possibility of demonstrative scientific knowledge - is expressed in the way that the body is structured, as it affects the mind.

Physics and its foundations were central to Descartes' thought. Although today he is probably best known for his metaphysics of mind and body, or for his epistemological program, in the seventeenth century Descartes was at very least equally well known for his mechanistic physics and the mechanist world of geometrical bodies in motion which he played a large role in making acceptable to his contemporaries. In this essay I shall outline Descartes' mechanical philosophy in its historical context. After some brief remarks on the immediate background to Descartes' program for physics, and a brief outline of the historical development of his physics, we shall discuss the foundations of Descartes' physics, including his concepts of body and motion and his views on the laws of motion.

BACKGROUND

Before we can appreciate the details of Descartes’ physics, we must appreciate something of the historical context in which it emerged and grew.

Most important to the background was, of course, the Aristotelian natural philosophy that had dominated medieval thought. Aristotelian natural philosophy had come under significant attack in what came to be known as the Renaissance.

“I resolved one day to . . . use all the powers of my mind in choosing the paths I should follow” (Discourse Part I: AT VI 10: CSM I 116). Thus Descartes introduces his account of his celebrated first solitary retreat during the winter of 1619-20. But he goes on to note that he decided to postpone actually embarking on his life's work until he had reached “a more mature age than twenty-three, as [he] then was ” (Part II: AT VI 22: CSM 1122). Toward the end of the winter of 1619-20, then, he began to travel, and this occupied “the next nine years”; only after these “nine years ” did he finally work out his philosophy, which was to be “more certain than the commonly accepted one” (Part III: AT VI 28, 30: CSM I 125-6). This period of Descartes' early life is obscured by the errors of his chief biographers, which have been repeated down the centuries. There is a marked tendency to bring forward his interest in science and the search for its foundations - an interest which in fact developed gradually and relatively late.

Descartes' concept of science can be understood only by paying careful attention to the historical context in which it was constructed. The scientific revolution of the seventeenth century involved two related developments: a change in scientific practice (or, more accurately, a whole series of such changes) which is reflected in the founding of new scientific societies such as the Royal Society and the Academie royale des sciences, and a complementary change in how natural philosophers described the kind of knowledge that resulted from the new scientific practices. Descartes contributed to both developments. He shared this distinction with such eminent figures as Galileo Galilei, Francis Bacon, William Harvey, Robert Boyle, Christian Huygens, and Isaac Newton, all of whom were concerned both with improving our knowledge of nature and with clarifying the status of that knowledge.

It would be an obvious oversimplification to classify all the natural philosophers of the seventeenth century as, in some fundamental sense, proposing the same scientific theories. It is equally unsatisfactory to suggest that they all accepted the same theory of science or the same model of scientific knowledge.

SOME PRELIMINARY REFERENCE POINTS ON THE SUBJECT

Autonomous, independent, spontaneous foundation of knowledge, understanding, feeling, imagination? Alienating, idealist, bourgeois humanist, phallogocentric delusion? Does the subject lie between these two polar opposite descriptions of it, does it span them and, like a Pascalian paradox, fill all the space between, or does it lie elsewhere entirely, perhaps in a Utopia? Is belief in the subject a necessary alienation, an alienation heureuse, a transcendental illusion of the Kantian kind? Is the subject an outmoded peg on which humanism used to hang its credentials and which can be abandoned along with the rest of the humanist paraphernalia? Or, to change metaphor, would such a rejection involve throwing the baby out with the bathwater? Is the concept of the subject necessary to any meditation on ethics, and, if so, need it be more than an “operational concept”? Or should this idea be shunned as a manifestation of the worst kind of paternalism? Contemporary French philosophy returns incessantly to the subject - recent thinking on ethics and politics, and in particular on Auschwitz and on Heidegger, has made the issue a burning one once again - "through flame or ashes, but. . . inevitably, " to use Derrida's concluding words in De l'Esprit. Having deposed the subject so firmly and with such apparent haste and delight in the 1960s and 1970s, French philosophers are now seeming to repent at leisure. The "death of man" (Foucault) and the "ends of man" (Derrida) are now seen to have lacked the radical finality with which their celebration endowed them twenty years earlier.

In Sartre's ontology what differentiates human being from all other being is precisely nothing. Or more accurately, it is a nothingness. In rewriting the sentence I have subtly changed it. Human being is not the same as the rest of being but is distinguished from it by a separating nothingness. Have I merely effected a sleight of hand? Is this nothingness a futile hypostatization? Or is it in reality a disguised something?

When the Greek Atomists declared that reality consisted of atoms and void, it was easy to grasp that the void was real without being a substance. We can see a hole. Clearly, emptiness was necessary if atoms were to group and regroup themselves in the forms that make up the universe. But the Atomist's nonbeing does not do anything; it is being in the form of self-moving atoms that is responsible for both relative permanencies and change. By contrast, Sartre puts all signifying activity where there is nothingness. And where is this nothingness? He tells us that "Nothingness lies coiled in the heart of being-like a worm" (p. 56). But this metaphor is something of an enigma and requires explanation. One thing is sure: Where there is nothingness, there is consciousness, but the two are not quite synonyms. And in one context Sartre speaks of "little pools of nonbeing" existing out there in the world (p. 53). Consciousness and nothingness are dependent on being, but they are not being. Sartre's ontology is a phenomenological description of the relation of this no-thing, which is consciousness, to the being on which it depends.

The purpose of this essay is to reflect on Sartre as a philosopher of the imagination in order better to describe and assess his approach to the philosophy of history. Sartre was, of course, an existentialist and we shall consider what it means to formulate an “existentialist” philosophy of history. But his was equally a philosophy of consciousness and the paradigm of consciousness for him was imaginative consciousness. Realizing this fact will open the door to a more adequate comprehension of his work as a whole, but especially his social thought, including his theory of history. For a basic thesis I wish to defend is that Sartre likens the intelligibility of history to that of an artwork because he considers the former as much the product of creative freedom as he does the latter. So we shall begin with a reading of major theses from his Psychology of Imagination and move through his posthumously published works, The War Diaries and the Cahiers pour une morale, in order to observe their expansion and application in both volumes of the Critique of Dialectical Reason and The Family Idiot. In so doing, we shall try to make sense of Sartre's claim that history in general and his Flaubert study in particular constitute “a novel that is true” (un roman vrai).

This collection of essays, by some of the foremost interpreters of Sartre from Europe and the United States, was composed specifically for the new series of Cambridge Companions to Major Philosophers. None of the essays has been published previously elsewhere. The contributors range from the most senior and established Sartrean scholars to some of the most promising and lively of the younger generation of critics. As editor, my task was to commission a broad range of essays, covering the major aspects of Sartre's philosophical work and its implications, in line with the purpose of the new Cambridge series. What struck me most forcibly on receipt of the typescripts, was the originality, density, and cohesion of the interpretations. They not only present a generous and balanced view of the wide variety of Sartre's philosophy, but also all make a contribution to the “new” Sartre, that is to the view of Sartre which has been gradually emerging since his death in 1980, as a figure whose diversity was far from being mastered, who could not, without distortion and impoverishment, be identified with the “classical existentialist” of the 1940s, and whose relationship to Structuralism and Post- Structuralism, as well as to psychoanalysis, Marxism, and literary theory, was far more complex than had been generally supposed. Suffering, since the 1960s, from the backlash of rejection that exceptional popularity and fame brings in its wake, Sartre was commonly used as the humanist target against whom nascent Structuralist, Marxist, and Deconstructionist critics could test their arms.

The title of the present study represents a philosophical wager. After all, Sartre never produced a completed ethical system even though his entire work is shot through with the ethical problematic. It will consequently be necessary for this study to account for the insistent recurrence of the moral question in Sartre's works as well as for the reasons why he was never willing to answer this question in any definitive manner.

To be sure, Sartre did, in fact, write on ethical questions. His Notebooks for an Ethic (1947) are subsequent to Being and Nothingness (1943); two other texts (1964 and 1965) are subsequent to the Critique of Dialectical Reason (i960). The first of these are notes for lectures given by Sartre at the Gramsci Institute in Rome (1964); the second (1965) are notes intended for a lecture at Cornell University canceled at the last moment by Sartre in protest against American bombings in Vietnam. The Notebooks for an Ethic, published posthumously in 1983, are a collection of fragmentary comments or aphorisms without any single emphasis. The two other texts (1964 and 1965) remain unpublished. I shall refer to these latter works as The Rome Lectures and The Cornell Notes. These are coherent texts that set forth fully developed lines of reasoning. Moreover all three of these texts have in common the fact that they were never published by Sartre and consequently, in Sartre's eyes, offered no satisfactory philosophical solution to the ethical question.