Jean-Baptiste Lamarck: La marche de la nature

Lamarck’s innovative science of transforming living entities, “la marche de la nature,” later called ‘evolution,’ received various interpretations, mostly relating him to the natural history and physical sciences of his time. I argue that the social discourses and practices of his time, a period of social and political turmoil, of novel institutions and shifting boundaries, when the mingling of scientific and social discourses and of professionalization of the sciences took place side by side, was crucial for his innovations. Lamarck offered an innovative conceptual scheme by resorting to a new repertoire of models about classification and change found in contemporaneous social-political discourses. He posited a model combining time, genealogy, and causality, thus history, that provided a description and analysis of processes of development and of change, the impact of the environment on active living entities, the emergence of complexity and of complex organization. I analyze his transition period, explicate his mature position, and his neurophysiological psychology. Lamarck “naturalized” human behavior by putting it on a par with the behavior of any other living organism; starting from the lowest living organizational form he wove together the environment, the living body nervous system and behavior to posit a systematic evolutionary account of their interactions, producing the first ever version of an evolutionary ‘self,’ a new conception of ‘internality,’ and the physiological mechanisms supporting them. I end with a review of the historiography on Lamarck’s work and suggest to view his taxonomic and his evolutionary enterprises as an integrated framework—his biologie.