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.”[21] 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.
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[22]: they are different ways of organizing the metaphysical flux, “separate melodic lines in constant interplay with one another.”[23] 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?”[24]