The article deals with the argument about free will and determinism between A. I. Herzen (1812—70) and his son, the physiologist A. A. Herzen (1839—1906). The topic, sufficiently familiar to Herzen scholars, interests me above all for its relevance to the history of science. The polemics between father and son touched upon such burning questions of the day as materialism in understanding human beings, positivism as scientific methodology, and the relation of the human sciences to the natural sciences. Seeing physiological (...) materialism as a threat to the values he shared, Herzen the father sought to convince his son of the limitations of mechanistic explanation. At first, Herzen had invested his hopes in the human sciences which were then in the course of forming disciplines — psychology, sociology, and history. He believed they would encompass freedom and consciousness, rejected by the natural sciences, as their subject-matter. But, when it had become clear that these disciplines were following the model of the natural sciences, Herzen then abandoned arguments taken from science and turned towards literature. His argument with his son, which was to do with rethinking rationality, was both critical and constructive for the nascent human sciences. (shrink)