Some philosophers build systems, and some demolish the ground on which systems are built. Gilles Deleuze did both at once. His work is, on one hand, among the most ambitious metaphysical undertakings of the twentieth century — an ontology of difference and multiplicity that aims to rewrite the entire history of Western philosophy. On the other, it is a war machine directed against the way Western thought has always pictured itself: against the primacy of identity, resemblance, and representation. Deleuze did not want to add one more doctrine to the catalogue; he wanted to change the very image of what it means to think. And he did so by forging a vocabulary of his own — difference in itself, the virtual, rhizome, body without organs, plane of immanence — that made his books at once fascinating and notoriously difficult.

1. Life, context, and method

1.1 A Parisian trajectory

Gilles Deleuze was born in Paris in 1925 and died there in 1995. He studied philosophy at the Sorbonne in the immediate postwar years, amid the dominance of phenomenology, existentialism, and Alexandre Kojève’s Hegelian reading of Hegel. Deleuze took an oblique path away from these reigning currents early on. He taught at the lycée level, at the Sorbonne, in Lyon, and from 1969 at the University of Paris VIII (Vincennes), where his lectures became legendary. He suffered from chronic respiratory illness for much of his life, which ended in 1995.

Deleuze is usually placed under the label of post-structuralism, alongside Foucault, Derrida, and Lyotard — a generation that, having inherited structuralism, refused to treat structure as a stable, closed form. The label is useful but should be used with care: Deleuze always regarded himself, first and foremost, as a metaphysician, someone who creates concepts about being and difference, not merely a critic of linguistic structures.

1.2 The monographs and the method

The first half of Deleuze’s work consists of monographs on other philosophers: Empiricism and Subjectivity (on Hume, 1953), Nietzsche and Philosophy (1962), Kant’s Critical Philosophy (1963), Bergsonism (1966), and two books on Spinoza — Spinoza and the Problem of Expression (1968) and Spinoza: Practical Philosophy (1970, expanded in 1981). These are not neutral academic commentaries. Deleuze described his method, almost as a confession, as a way of “taking an author from behind” and making him produce something that was Deleuze’s own and yet not literally in him. One reads Hume, Nietzsche, Bergson, and Spinoza less to reconstruct what they said than to extract from them an alternative lineage: a counter-history of philosophy, made up of thinkers of immanence, force, and difference, set against the dominant lineage of identity and transcendence.

This freedom of interpretation is also, as we shall see, the target of one of the principal criticisms leveled at Deleuze.

1.3 The major works and the partnership with Guattari

In 1968 and 1969, Deleuze published the two works that constitute his own system: Difference and Repetition (his doctoral thesis) and The Logic of Sense. These are books by Deleuze alone, and in them the essentials of his metaphysics are laid out.

In 1969, Deleuze met Félix Guattari (1930–1992), a psychoanalyst and political militant connected to the La Borde clinic. Their collaboration produced four books: Anti-Oedipus (1972) and A Thousand Plateaus (1980), the two volumes of Capitalism and Schizophrenia; the short Kafka: Toward a Minor Literature (1975); and What Is Philosophy? (1991). For rigorous reading, it is decisive to distinguish what belongs to Deleuze alone from what arises in the partnership. Concepts such as difference in itself, the virtual, and the eternal return belong to the metaphysical Deleuze of 1968–69; concepts such as desiring-machines, body without organs, rhizome, assemblage, and deterritorialization are forged with Guattari, in a register that mixes philosophy, critical psychoanalysis, anthropology, and politics.

In parallel, Deleuze authored books on art and cinema on his own: the study of the painter Francis Bacon (The Logic of Sensation, 1981) and the two volumes of Cinema: The Movement-Image (1983) and The Time-Image (1985).

2. The critique of the dogmatic image of thought

Deleuze’s point of departure in Difference and Repetition is an accusation: philosophy operates, almost always without knowing it, under a dogmatic image of thought. This image assumes that thinking is natural, that thought spontaneously tends toward the true, that error is the only accident to be feared, and that to know is fundamentally to recognize — to find again in the object the form of identity.

Resting on this image is what Deleuze calls the philosophy of representation. To represent is to subject difference to four instances that domesticate it: the identity of the concept, resemblance in perception, opposition between predicates, and analogy in judgment. Since Plato and Aristotle, difference has only been thought as something between two terms already identical — the specific difference within a genus, difference as negation or contradiction. In every case, difference is secondary, derived, mediated by a prior identity. It is never thought in itself.

The result, for Deleuze, is that Western metaphysics has systematically subordinated difference to the Same. His ambition is to reverse this hierarchy.

3. Difference in itself and repetition

3.1 Thinking difference without identity

The central thesis of Difference and Repetition is that difference comes first. There are no identities that subsequently enter into relations of difference; there is a field of pure differences, intensities, and singularities from which identities are constituted as secondary, relatively stable effects. Identity is the product, not the principle. To think difference “in itself” means to think it without subjecting it to opposition, negation, or the concept of something identical that it would differentiate.

3.2 The repetition that produces the new

From this follows a counterintuitive conception of repetition. In common sense, to repeat is to produce the same. For Deleuze, true repetition does not repeat the identical but produces difference. Reading Nietzsche’s eternal return, he holds that what returns is not the same but the very power of differentiating: the eternal return is a selective principle that affirms difference and expels everything belonging to the order of reactive identity. To repeat, in this strong sense, is to create.

3.3 The virtual and the actual

To support this ontology, Deleuze elaborates — chiefly drawing on Bergson — the distinction between the virtual and the actual. The virtual is neither the unreal nor the merely possible: it is fully real, though not actual. Deleuze insists on this point, and the distinction is among the most important in his philosophy. The possible, in the tradition, is a tracing of the real: it has the same form as the real and simply “lacks” existence, so that its realization is the mere addition of existence to something already given. The virtual, by contrast, does not resemble the actual that emerges from it: the actual is constituted through actualization, a process of differenciation that creates genuinely new forms, not prefigured in the virtual. This is why the virtual is the key to an ontology of creation: the real does not realize a possible already drawn out but actualizes a virtual field of differences, inventing what was not previously sketched.

4. Transcendental empiricism and the univocity of being

4.1 Transcendental empiricism

Deleuze calls his position transcendental empiricism. The formula is deliberately paradoxical. Like Kant, he seeks the conditions of what is given to experience; but against Kant, he refuses to make those conditions universal categories of a constituting subject. The conditions must not be broader than the conditioned: what is sought is not the conditions of all possible experience but the genesis of real experience in its singularity. The Deleuzean “transcendental” is thus a field of pre-individual and impersonal intensities and singularities — prior to the constituted subject and object — from which these emerge.

4.2 The univocity of being

Underlying all this is Deleuze’s most radical ontological thesis: the univocity of being. Being is said in one and the same sense of everything that is, but what it says in this single sense is difference. Deleuze constructs this thesis from a precise lineage, which he names explicitly: Duns Scotus, who thought being as univocal; Spinoza, who made being a single substance expressed in infinite immanent modes; and Nietzsche, who thought the eternal return as the being of becoming. Against the analogy of being in Aristotle and the Thomistic tradition — according to which “being” is said in different senses depending on the categories — univocity affirms that there are no hierarchical levels of being, no supreme Being in which the rest would participate by degrees.

4.3 The plane of immanence

The consequence is an absolute immanence. There is no transcendence — no God separate from the world, no Platonic Idea above the sensible, no constituting subject outside the field it constitutes. Everything takes place on a single plane of immanence, a direct inheritance from the Spinoza for whom God is Nature (Deus sive Natura). Deleuze’s philosophy is, in this fundamental sense, one of the most consistent philosophies of immanence in history — a methodical refusal of any instance that would claim to judge the real from outside it.

5. The concepts forged with Guattari

The joint work with Guattari translates this metaphysics into a political, clinical, and cultural register. It is here that the most famous concepts are born — and it is important to remember that they are, strictly speaking, Deleuzo-Guattarian concepts.

5.1 Desire as production

The target of Anti-Oedipus is the conception of desire as lack, dominant in the psychoanalysis of Freud and, above all, of Lacan. For that tradition, to desire is to desire what one lacks. Deleuze and Guattari invert the equation: desire is not lack but production. Desire is a positive, productive force that constructs realities and directly invests the social field — not the closed theater of the Oedipal family, but a “factory.” Hence the desiring-machines: the unconscious is not a theater of representations (Oedipus, father, mother) but a factory that produces and connects flows. The critique of psychoanalysis is that it reduced the productivity of desire to the familial triangle, “Oedipalizing” the unconscious and placing it in the service of reproducing the established order.

5.2 Body without organs and assemblage

The body without organs — an expression borrowed from the poet Antonin Artaud — designates a body understood not as a hierarchized, functionally fixed organism, but as a surface of intensities, a field of potentials across which desire circulates before being captured by an organization. The assemblage (agencement) is the real unit of analysis: not the individual, not the structure, but the concrete arrangement that connects bodies, signs, affects, institutions, and statements. An assemblage has no essence; it is defined by what it does, by the connections it establishes.

5.3 Rhizome against tree

The most widely diffused concept — often reduced to a cliché — is the rhizome, set out at the opening of A Thousand Plateaus. Deleuze and Guattari oppose two models of thought and organization. The arborescent model (the tree) has a single root, a central trunk, hierarchy, ordered branching: it is the model of unity, filiation, and foundation. The rhizome — like the underground stem of certain plants — is a multiplicity without center or hierarchy, in which any point can connect to any other, which has neither beginning nor end but only a middle through which it grows and overflows. The authors set out its principles: connection, heterogeneity, multiplicity, asignifying rupture. The rhizome is at once a figure for thought, for politics, and for culture — a model of multiplicity that escapes the logics of unity and the center.

5.4 Territorialization, deterritorialization, and nomadism

Finally, the pair territorialization / deterritorialization. Every assemblage organizes itself by fixing a “territory” — codes, habits, identities. But every territory is traversed by lines of flight, forces of deterritorialization that undo it and open it to the new, possibly reterritorializing afterward in another arrangement. Nomadism is the ethico-political figure of this dynamic: the nomad occupies space without striating it into fixed properties, opposing the State apparatus, which captures and codes. Note the continuity with the metaphysics of 1968: deterritorialization is the political-social name for what, in the ontology, was the primacy of difference and creation over identity.

6. Philosophy as the creation of concepts

In their last joint book, What Is Philosophy? (1991), Deleuze and Guattari offer a definition of the discipline itself. Philosophy does not contemplate, reflect, or communicate — these would be empty pretensions. Philosophy creates concepts. Each concept is a dated and signed creation, a response to a problem, traced upon a plane of immanence that gives it consistency. Three modes of thought are thereby distinguished: philosophy, which creates concepts; science, which creates functions and propositions (operating with references and states of affairs); and art, which creates affects and percepts (blocks of sensation). This definition is at the same time a self-description: the whole of Deleuze’s work can be read as a vast workshop of conceptual creation.

Critical analysis

Deleuze’s strength is incontestable on at least two fronts. First, his metaphysical originality: few twentieth-century philosophies dared so ambitious a positive ontology, and the attempt to think difference without subordinating it to identity renewed problems that had seemed exhausted since Plato and Aristotle. Second, his interdisciplinary fertility: his concepts migrated into political theory, cultural studies, aesthetics, film theory, architecture, and even the sciences of complexity, with a productivity few contemporary philosophers have matched.

The criticisms, however, deserve to be presented fairly. The first is terminological obscurity: Deleuze’s vocabulary is dense, and the reader may struggle to distinguish between genuine conceptual rigor and a proliferation of terms whose precise content remains elusive. The second concerns the Deleuzean reading of other philosophers. Deleuze himself acknowledged the violence of his method (“taking the author from behind”); historians of philosophy often argue that his Bergson, his Spinoza, or his Nietzsche are as much Deleuze’s creations as faithful reconstructions — which is not necessarily a defect, provided one distinguishes Deleuze-the-reader from Deleuze-the-commentator.

The third controversy is the so-called Sokal affair. In Intellectual Impostures (French, 1997; English, Fashionable Nonsense, 1998), the physicists Alan Sokal and Jean Bricmont accused several French intellectuals — among them Lacan, Kristeva, Baudrillard, and the Deleuze-Guattari pair — of using terms from mathematics and physics (differential calculus, quantum mechanics, chaos theory) imprecisely, out of context, and with no real necessity, lending philosophical texts an unwarranted veneer of scientificity. Two things are worth noting in fairness. On one hand, Sokal and Bricmont declared they did not intend to judge the overall philosophical value of these authors, but only their use of specific scientific concepts. On the other, Deleuze’s defenders reply that his use of such terms was manifestly metaphorical or conceptual, not a claim to do science — so that the critique, while pointing to a real problem of imprecision, may rest on a misunderstanding about the genre of the discourse. The debate remains open and offers a good exercise in critical reading for the student: it is a matter of assessing, case by case, when borrowing a scientific concept illuminates a philosophical problem and when it merely obscures it.

Legacy

Deleuze’s influence runs through contemporary philosophy and the human sciences. In political theory, Michael Hardt and Antonio Negri took up Deleuzo-Guattarian concepts — multitude, productive desire, immanence — in Empire (2000) and its sequels. In cultural studies and aesthetic theory, the notions of rhizome, assemblage, and deterritorialization have become standard tools. The so-called new materialisms and object-oriented ontologies engage directly with his immanence and his emphasis on nonhuman forces. In film theory, the two volumes on the movement-image and the time-image are required reading. And in architecture, concepts such as the fold, multiplicity, and smooth/striated space were explicitly mobilized by architects and theorists. Few twentieth-century philosophers have been read so widely outside philosophy — which is at once the measure of his fertility and the source of many of the misunderstandings surrounding his work.

  • Gilles Deleuze, Difference and Repetition (1968).
  • Gilles Deleuze, The Logic of Sense (1969).
  • Gilles Deleuze, Nietzsche and Philosophy (1962).
  • Gilles Deleuze, Spinoza: Practical Philosophy (1970).
  • Gilles Deleuze and Félix Guattari, Anti-Oedipus: Capitalism and Schizophrenia 1 (1972).
  • Gilles Deleuze and Félix Guattari, A Thousand Plateaus: Capitalism and Schizophrenia 2 (1980).
  • Gilles Deleuze and Félix Guattari, What Is Philosophy? (1991).
  • Gilles Deleuze, Cinema 1: The Movement-Image (1983) and Cinema 2: The Time-Image (1985).
  • Alan Sokal and Jean Bricmont, Intellectual Impostures / Fashionable Nonsense (1997/1998) — for the controversy, read critically.

← Articles