Deleuze taught at various lycées (Amiens, Orléans, Louis le Grand) until 1957, when he took up a position at the Sorbonne. In 1953, he published his first monograph, Empiricism and Subjectivity, on Hume. He married Denise Paul "Fanny" Grandjouan in 1956. From 1960 to 1964 he held a position at the Centre National de Recherche Scientifique. During this time he published the seminal Nietzsche and Philosophy (1962) and befriended Michel Foucault. From 1964 to 1969 he was a professor at the University of Lyon. In 1968 he published his two dissertations, Difference and Repetition (supervised by Gandillac) and Expressionism in Philosophy: Spinoza (supervised by Alquié).
In 1969 he was appointed to the University of Paris VIII at Vincennes/St. Denis, an experimental school organized to implement educational reform. This new university drew a number of talented scholars, including Foucault (who suggested Deleuze's hiring), and the psychoanalyst Félix Guattari. Deleuze taught at Vincennes until his retirement in 1987.
Deleuze, a heavy smoker, suffered from lung cancer. Although he had a lung removed, the disease had spread throughout his pulmonary system. Deleuze underwent a tracheotomy, lost the power of speech and considered himself 'chained like a dog' to an oxygen machine. By the last years of his life, simple tasks such as handwriting required laborious effort. In 1995, he committed suicide, throwing himself from the window of his apartment.
The novelist Michel Tournier, who knew Deleuze when both were students at the Sorbonne, described him thus:
Deleuze himself almost entirely demurred from autobiography. When once asked to talk about his life, he replied: "Academics' lives are seldom interesting. When a critic seized upon Deleuze's unusually long, uncut fingernails as a revealing eccentricity, he drily noted a more obvious explanation: "I haven't got the normal protective whorls, so that touching anything, especially fabric, causes such irritation that I need long nails to protect them. Deleuze concludes his reply to this critic thus:
Deleuze's main philosophical project in his early works (i.e., those prior to his collaborations with Guattari) can be baldly summarized as a systematic inversion of the traditional metaphysical relationship between identity and difference. Traditionally, difference is seen as derivative from identity: e.g., to say that "X is different from Y" assumes some X and Y with at least relatively stable identities. To the contrary, Deleuze claims that all identities are effects of difference. Identities are not logically or metaphysically prior to difference, Deleuze argues, "given that there exist differences of nature between things of the same genus. That is, not only are no two things ever the same, the categories we use to identify individuals in the first place derive from differences. Apparent identities such as "X" are composed of endless series of differences, where "X" = "the difference between x and x'", and "x" = "the difference between...", and so forth. Difference goes all the way down. To confront reality honestly, Deleuze claims, we must grasp beings exactly as they are, and concepts of identity (forms, categories, resemblances, unities of apperception, predicates, etc.) fail to attain difference in itself. "If philosophy has a positive and direct relation to things, it is only insofar as philosophy claims to grasp the thing itself, according to what it is, in its difference from everything it is not, in other words, in its internal difference.
Like Kant and Bergson, Deleuze considers traditional notions of space and time as unifying categories imposed by the subject, that is, he considers them to be forms of identity. Therefore he concludes that pure difference is non-spatio-temporal; it is an idea, what he calls "the virtual". (The coinage refers not to the "virtual reality" of the computer age, but to Proust's definition of the past: "real without being actual, ideal without being abstract.) While Deleuze's virtual ideas superficially resemble Plato's forms and Kant's ideas of pure reason, they are not originals or models, nor do they transcend possible experience; instead they are the conditions of actual experience, the internal difference in itself. "The concept they [the conditions] form is identical to its object. A Deleuzean idea or concept of difference is not a wraith-like abstraction of an experienced thing, it is a real system of differential relations that creates actual spaces, times, and sensations.
Thus Deleuze, alluding to Kant and Schelling, at times refers to his philosophy as a transcendental empiricism. In Kant's transcendental idealism, experience only makes sense when organized by intellectual categories (such as space, time, and causality). Taking such intellectual concepts out of the context of experience, according to Kant, spawns seductive but senseless metaphysical beliefs. (For example, extending the concept of causality beyond possible experience results in unverifiable speculation about a first cause.) Deleuze inverts the Kantian arrangement: experience exceeds our concepts by presenting novelty, and this raw experience of difference actualizes an idea, unfettered by our prior categories, forcing us to invent new ways of thinking (see below, Epistemology).
Simultaneously, Deleuze claims that being is univocal, i.e., that all of its senses are affirmed in one voice. Deleuze borrows the doctrine of ontological univocity from the medieval philosopher John Duns Scotus. In medieval disputes over the nature of God, many eminent theologians and philosophers (such as Thomas Aquinas) held that when one says that "God is good", God's goodness is only analogous to human goodness. Scotus argued to the contrary that when one says that "God is good", the goodness in question is the exact same sort of goodness that is meant when one says "Jane is good". That is, God only differs from us in degree, and properties such as goodness, power, reason, and so forth are univocally applied, regardless of whether one is talking about God, a man, or a flea.
Deleuze adapts the doctrine of univocity to claim that being is, univocally, difference. "With univocity, however, it is not the differences which are and must be: it is being which is Difference, in the sense that it is said of difference. Moreover, it is not we who are univocal in a Being which is not; it is we and our individuality which remains equivocal in and for a univocal Being. Here Deleuze at once echoes and inverts Spinoza, who maintained that everything that exists is a modification of the one substance, God or Nature. For Deleuze, there is no one substance, only an always-differentiating process, an origami cosmos, always folding, unfolding, refolding. Deleuze summarizes this ontology in the paradoxical formula "pluralism = monism".
Difference and Repetition is Deleuze's most sustained and systematic attempt to work out the details of such a metaphysics, but his other works develop similar ideas. In Nietzsche and Philosophy (1962), for example, reality is a play of forces; in Anti-Oedipus (1972), a "body without organs"; in What Is Philosophy? (1991), a "plane of immanence" or "chaosmos".
Deleuze's peculiar readings of the history of philosophy stem from this unusual epistemological perspective. To read a philosopher is no longer to aim at finding a single, correct interpretation, but is instead to present a philosopher's attempt to grapple with the problematic nature of reality. "Philosophers introduce new concepts, they explain them, but they don't tell us, not completely anyway, the problems to which those concepts are a response. [...] The history of philosophy, rather than repeating what a philosopher says, has to say what he must have taken for granted, what he didn't say but is nonetheless present in what he did say. (See below, Deleuze's interpretations.)
Likewise, rather than seeing philosophy as a timeless pursuit of truth, reason, or universals, Deleuze defines philosophy as the creation of concepts. For Deleuze, concepts are not identity conditions or propositions, but metaphysical constructions that define a range of thinking, such as Plato's ideas, Descartes's cogito, or Kant's doctrine of the faculties. A philosophical concept "posits itself and its object at the same time as it is created. In Deleuze's view, then, philosophy more closely resembles practical or artistic production than it does an adjunct to a definitive scientific description of a pre-existing world (as in the tradition of Locke or Quine).
In his later work (from roughly 1981 onward), Deleuze sharply distinguishes art, philosophy, and science as three distinct disciplines, each analyzing reality in different ways. While philosophy creates concepts, the arts create new qualitative combinations of sensation and feeling (what Deleuze calls "percepts" and "affects"), and the sciences create quantitative theories based on fixed points of reference such as the speed of light or absolute zero (which Deleuze calls "functives"). According to Deleuze, none of these disciplines enjoy primacy over the others: they are different ways of organizing the metaphysical flux, "separate melodic lines in constant interplay with one another. For example, Deleuze does not treat cinema as an art representing an external reality, but as an ontological practice that creates different ways of organizing movement and time. Philosophy, science, and art are equally, and essentially, creative and practical. Hence, instead of asking traditional questions of identity such as "is it true?" or "what is it?", Deleuze proposes that inquiries should be functional or practical: "what does it do?" or "how does it work?
But how does Deleuze square his pessimistic diagnoses with his ethical naturalism? Deleuze claims that standards of value are internal or immanent: to live well is to fully express one's power, to go to the limits of one's potential, rather than to judge what exists by non-empirical, transcendent standards. Modern society still suppresses difference and alienates persons from what they can do. To affirm reality, which is a flux of change and difference, we must overturn established identities and so become all that we can become—though we cannot know what that is in advance. The pinnacle of Deleuzean practice, then, is creativity. "Herein, perhaps, lies the secret: to bring into existence and not to judge. If it is so disgusting to judge, it is not because everything is of equal value, but on the contrary because what has value can be made or distinguished only by defying judgment. What expert judgment, in art, could ever bear on the work to come?"
Deleuze's ideas have not spawned a school, as Lacan's did. But his major collaborations with Guattari (Anti-Oedipus, A Thousand Plateaus, and What Is Philosophy?) were best-sellers in France, and remain heavily cited in English-speaking academe. In 1994 and 1995, L'Abécédaire de Gilles Deleuze, an eight-hour series of interviews between Deleuze and Claire Parnet, aired on France's Arte Channel (a still from the program appears in the infobox above).
In the 1960s, Deleuze's portrayal of Nietzsche as a metaphysician of difference rather than a reactionary mystic contributed greatly to the plausibility of "left-wing Nietzscheanism" as an intellectual stance. In the 1970s, the Anti-Oedipus, written in a style by turns vulgar and esoteric, offering a sweeping analysis of the family, language, capitalism, and history via eclectic borrowings from Freud, Marx, Nietzsche, and dozens of other writers, was received as a theoretical embodiment of the anarchic spirit of May 1968.
In the 1980s and 1990s, almost all of Deleuze's books were translated into English. Like his contemporaries Foucault, Derrida, and Lyotard, Deleuze's influence has been most strongly felt in North American humanities departments, particularly in literary theory. There, Anti-Oedipus and A Thousand Plateaus are sometimes regarded as major statements of post-structuralism and postmodernism, though Deleuze and Guattari did not describe their work in those terms. Within this context, Deleuze's work is more usually identified as part of "continental philosophy".
Deleuze has attracted critics as well. The following list is not exhaustive, and gives only the briefest of summaries.
In Modern French Philosophy (1979), Vincent Descombes argues that Deleuze's account of a difference that is not derived from identity (in Nietzsche and Philosophy) is incoherent, and that his analysis of history in Anti-Oedipus is 'utter idealism', criticizing reality for falling short of a non-existent ideal of schizophrenic becoming.
In What Is Neostructuralism? (1984), Manfred Frank claims that Deleuze's theory of individuation as a process of bottomless differentiation fails to explain the unity of consciousness.
In "The Decline and Fall of French Nietzscheo-Structuralism" (1994), Pascal Engel presents a global condemnation of Deleuze's thought. According to Engel, Deleuze's metaphilosophical approach makes it impossible to reasonably disagree with a philosophical system, and so destroys meaning, truth, and philosophy itself. Engel summarizes Deleuze's metaphilosophy thus: "When faced with a beautiful philosophical concept you should just sit back and admire it. You should not question it.
In Deleuze: The Clamor of Being (1997), Alain Badiou claims that Deleuze's metaphysics only apparently embraces plurality and diversity, remaining at bottom relentlessly monist. Badiou further argues that, in practical matters, Deleuze's monism entails an ascetic, aristocratic fatalism akin to ancient Stoicism.
In Reconsidering Difference (1997), Todd May argues that Deleuze's claim that difference is ontologically primary ultimately contradicts his embrace of immanence, i.e., his monism. However, May believes that Deleuze can discard the primacy-of-difference thesis, and accept a Wittgensteinian holism without significantly altering (what May believes is) Deleuze's practical philosophy.
In Fashionable Nonsense (1997), Alan Sokal and Jean Bricmont accuse Deleuze of abusing mathematical and scientific terms, particularly by sliding between accepted technical meanings and his own idiosyncratic use of those terms in his philosophical system. (See above, Deleuze's interpretations.) Deleuze's writings on subjects such as calculus and quantum mechanics are, according to Sokal and Bricmont, vague, meaningless, or unjustified. However, by Sokal and Bricmont's own admission, they suspend judgment about Deleuze's philosophical theories and terminology.
In Organs without Bodies (2003), Slavoj Žižek claims that Deleuze's ontology oscillates between materialism and idealism, and that the Deleuze of Anti-Oedipus ("arguably Deleuze's worst book"), the "political" Deleuze under the "'bad' influence" of Guattari, ends up, despite protestations to the contrary, as "the ideologist of late capitalism". Žižek also calls Deleuze to task for allegedly reducing the subject to "just another" substance and thereby failing to grasp the nothingness that, according to Lacan and Žižek, defines subjectivity. What remains worthwhile in Deleuze's oeuvre, Žižek finds, are precisely those concepts closest to Žižek's own ideas.
In Out of this World: Deleuze and the Philosophy of Creation (2006), Peter Hallward argues that Deleuze's insistence that being is necessarily creative and always-differentiating entails that his philosophy can offer no insight into, and is supremely indifferent to, the material, actual conditions of existence. Thus Hallward claims that Deleuze's thought is literally other-worldly, aiming only at a passive contemplation of the dissolution of all identity into the theophanic self-creation of nature.
(Near complete bibliography, including various translations) By Gilles Deleuze
Most of Deleuze's courses are available, in several languages, here