Loeb was a philosophically inclined physiologist and biologist noted chiefly for his experimental work on parthenogenesis (reproduction without fertilization) and for his staunch defence of biological mechanism. Popular interest, attended by some controversy, was aroused by Loeb’s pioneering experiments, beginning in 1899, when he successfully brought about the development of sea-urchin larvae from unfertilized eggs by exposing them to controlled changes in their environment.

From his scientific researches, which were designed to lay the foundations for a common dynamic of all vital phenomena and to illuminate the nature of volition, Loeb drew wide-ranging philosophical conclusions. He contended that not only vital phenomena, but human phenomena too, realized themselves in a purely mechanical way and were explicable solely in terms of physical and chemical concepts. Thus Loeb believed that we have only to improve our understanding of hereditary conditions in order to grasp the source and condition of all human activity. For him, even moral behaviour was no less the forced or automatic reaction of the organism as a whole than was the movement of a plant. Loeb’s rigorous application of his pan-mechanistic or ‘tropistic’ thesis led him to an extreme, reductive philosophical monism. Nevertheless, his views had considerable influence, for example on Thorstein Veblen.

Sources: Edwards; DFN; EF.