The birth of psychophysics through conatus: plasticity and the circuit of the individual in Hobbes

Abstract

This article investigates the genesis of Hobbesian psychophysics from the concept of conatus, demonstrating that it operates as a genetic principle that simultaneously gives rise to the description of the individual as a sentient body and to plasticity as a capacity for internal reconfiguration through experience. The plasticity in question does not correspond to the contemporary notion of neuroplasticity nor to any retrospective projection: it strictly designates properties deducible from conatus as defined in De Corpore XV — persistence, accumulation, and reorganization of movements in the living body. The investigation follows the differentiation of conatus into vital and reactive, examining how the encounter between external pressure and vital movement generates sensation, imagination, memory, passions, and deliberation. The central argument holds that plasticity emerges as a necessary consequence of the way conatus organizes the circuit from sensory impact to action. The article reconstructs this progression exclusively from Hobbes's texts — De Corpore, Leviathan, Elements of Law, De Homine, and Third Objections —, showing that the same structure enabling learning and habit formation also enables error, madness, and disorganization. The analysis demonstrates that the psychophysical circuit dissolves the mind-body dualism without incurring ontological reductionism, situating the Hobbesian individual as a plastic organism whose dispositions are formed, stabilized, and reorganized through accumulated experience.