Eugenio Rignano was an Italian positivist philosopher and founder (1907) and lifelong editor of the scientific journal Scientia. Rignano's first works were sociologically oriented, but he later turned to biology and philosophical biology. His major work, Psicologia del ragionamento (1920), places the activity of memory at the basis of all biological and psychic phenomena. Memory is an activity that, through the specific accumulation of concepts, makes possible the progressive adaptation of the organism to the environment, the formation of instincts and emotions, and, in higher organisms, of reasoning. According to Rignano, reasoning is "a series of operations or experiences merely thought out simply"; in other words, a series of operations performed in imagination. The results of these operations are also imagined and are assumed as the conclusions of the reasoning itself. This conception of reasoning, which Rignano derived chiefly from Ernst Mach, was later applied by...