The philosophical underpinnings of Emile Durkheim's thought have long been subject to a variety of very different interpretations, ranging from positivism to a kind of metaphysical realism. Alternatively, he has been read having undergone major shifts in his thought over the course of his career. I argue that the diverse philosophical moments in Durkheim's thought can be traced to two different traditions that played significant roles in his intellectual formation: First, there was the eclectic spiritualist tradition, with its roots in the thought of Maine de Biran, that was developed by Victor Cousin and transmitted through Cousin's amanuensis Paul Janet to Durkheim and dominated academic philosophy in France. Second, there was the Kantian phenomenalist tradition championed by Charles Renouvier, who, although wholly outside the university system, was widely read by young scholars in the latter decades of the Nineteenth Century who in turn led academic philosophy in new directions. Durkheim's sociological theorizing reflected these different currents in the philosophical climate of his day.