The tension between preformationism and the freedom of morphogenetic development, which we observed in examining Ruyer's work, also guides Catherine Malabou's philosophy. Malabou examines this tension through the notion of ‘plasticity’, which means the capacity of the living being to receive form and to give form, and also the capacity to explode form. Plasticity refers to the qualitative change that takes place both at the level of cells (cell plasticity) and the brain (neuroplasticity), and that can be either creative or destructive. It is destructive plasticity that is the most interesting for neurological and philosophical investigations, because it reveals the rupture between the cerebral and the mental, or between cerebral auto-affection and mental auto-affection. In these cases, we discover something that Malabou names the ‘cerebral unconscious’ – cerebral activity without consciousness. These discoveries open a gap between the brain and the mind, or between the biological and the transcendental origins of thinking. Deleuze and Guattari already started questioning the central role of the mind and asserted the importance of cerebral cognition. In a similar tone, Malabou argues that reason, or the field of the transcendental, is not something pre-formed and pre-given but is subject to epigenetic development. Reason is evolving, developing and changing in the same way as a living being is. In this sense, Malabou refers to the ‘epigenesis of reason’, which allows us to question the universal and necessary nature of transcendental reason.

Plasticity and Potentiality

The notion of plasticity first appears in Malabou's doctoral thesis on Hegel, which was later published under the title The Future of Hegel. Although originating from a close reading of Hegelian dialectics, the notion of plasticity is detached from the Hegelian vocabulary and, as Jacques Derrida pointed out in his ‘Preface’, extended to the realm of the living in general (Malabou 2005: xxiii). Malabou discusses plasticity as a general characteristic of life that defines the living being as capable of receiving form and also of giving form to its environment. However, to exercise its vital functions, an organism has to transform the reservoir of energy into something else; in other words, it has to make this energy explode to acquire new vital qualities. Here the word ‘plasticity’ acquires a third meaning, that of explosive substance (deriving from the French words plastiquer or plastiquage).