Alfred Fouillée, the French philosopher and sociologist, was a prolific writer, especially on political, social, and historical subjects. He was a lecturer in lycées at Douai and Montpellier, at the University of Bordeaux, and finally, from 1872 to 1875, at the École Normale in Paris. When he had to retire because of ill health, he devoted his time to his writings. Through most of his varied output there ran a common thread. This was a concern to reconcile the values of traditionally metaphysical or spiritualistic philosophy—above all, liberty and free will—with the deterministic and antimetaphysical findings of contemporary work in the natural sciences: a concern, that is, to reconcile philosophical idealism with scientific naturalism. Fouillée, who was not closely identified with any formal school of thought, thus represented a further step in the direction indicated...