Psychic Mechanics: The Foundational Role of Moritz Wilhelm Drobisch (1802-1896) in the Development of Psychophysics

This paper examines the pivotal role played by Moritz Wilhelm Drobisch (1802-1896) in the development of mathematical psychology, and his influence on the emergence of Fechner's psychophysics in 19th-century Germany. As a key figure in the Herbartian tradition in Leipzig, Drobisch refined Herbart's initial framework for applying mathematics to psychological phenomena while also addressing the fundamental theoretical challenges inherent in measuring intensive mental magnitudes. The study sheds light on how Drobisch's dual expertise in mathematics and philosophy enabled him to develop innovative methods for quantifying mental representations, most notably through his formulation of the "three-representation problem" as psychology's analog to celestial mechanics, and his mathematical treatment of qualitative color continua. By reconstructing the crucial yet overlooked connection between Drobisch's mathematical psychology and Gustav Theodor Fechner's psychophysics, this study sheds light on a critical chapter in the prehistory of experimental psychology, offering new perspectives on the mathematical foundations of modern behavioral sciences.