In recent biological research, the importance of epigenetics has been increasingly emphasized, leading to a renewed interest in Lamarck and his evolutionary theory. This study aims to examine how Lamarck’s theory of evolution has been reduced, since the nineteenth century, to the narrow concept of the “inheritance of acquired characteristics,” and to clarify the historical significance of this reconstruction. The core of Lamarck’s theory lay in his understanding of the physical phenomena of life, the relationship between body and mind, gradual evolution, and the physico-chemical principles governing the living world. However, in opposition to August Weismann’s germ-plasm theory in the late nineteenth century, Lamarck’s ideas were confined to the notion of acquired inheritance and subsequently reinterpreted in diverse forms of “Lamarckism” within biology, anthropology, psychology, and sociology, depending on time and context. As neo-Lamarckism emerged as a critical response to Weismannism, the gap between Lamarck’s original theory and later Lamarckisms became more pronounced, resulting in a narrow and often distorted evaluation of Lamarck’s place in the history of science. By examining the formation and reception of Lamarck’s ideas within their contemporary scientific context, and by analyzing the diverse reinterpretations of Lamarckism through processes of misunderstanding, reduction, and political appropriation, this study seeks to explore how the rise of modern epigenetics has reactivated Lamarckian problematics. Ultimately, it aims to illuminate the diachronic significance of Lamarck’s theory and its legacy in modern biology, contributing to broader meta-scientific discussions on the constructive nature of science.