Simondon's and Ruyer's philosophy influenced Gilles Deleuze and helped him to formulate his original theory of life. The traces of Simondon's philosophy can be felt in Deleuze's Difference and Repetition, where the interaction between the pre-individual state and individuation is transformed into the interplay between the virtual and the actual. Simondon's ideas are also present in Deleuze and Guattari's book A Thousand Plateaus, where they directly refer to Simondon while discussing the machinic phylum, an energetic power of materiality. Ruyer's works also appear in the footnotes of A Thousand Plateaus and have a more visible presence in Deleuze's book The Fold. Ruyer's concept of self-survey becomes an important theme in Deleuze and Guattari's What Is Philosophy?, where it is applied to describe the functioning of the brain. Thus, Simondon's and Ruyer's ideas are creatively employed in Deleuze's (and Guattari’s) philosophical project where they develop, evolve and create something new. In this chapter I will discuss those aspects of Deleuze's (and Guattari’s) philosophy that are related to the notion of an organism as follows: individuation as differentiation in Deleuze's Difference and Repetition, the reconceptualisation of the notion of an organism in A Thousand Plateaus, and the notion of the brain in What is Philosophy? Deleuze and Guattari take into account different theories of development, such as individuation and morphogenesis, to create a processual philosophy of life, where all living beings share the same formative materiality.

Individuation as Differentiation

Simondon's theory of individuation had a significant influence on Deleuze, who wrote a review of Simondon's book L’individu et sa genèse physico-biologique in 1966. As Deleuze points out, Simondon creates a profoundly original theory of individuation that presumes the existence of a metastable system. This metastable system, named as the pre-individual state, contains the disparation of at least two orders of magnitude, two disparate scales of reality. This disparation, or difference, exists as potential energy, a potentiality that structures and individuates reality. In this sense, Deleuze reads Simondon's theory of individuation as being methodologically close to his own philosophical project: ‘It seems to us that Simondon's perspective can be reconciled with a theory of intensive quantities, since each intensive quantity is a difference in itself […] Like any metastable system, it is a structure (not yet a synthesis) of the heterogeneous’ (Deleuze 2001: 44).