1911 Encyclopædia Britannica/Occasionalism
OCCASIONALISM (Lat. occasio, an event), in philosophy, a term applied to that theory of the relation between matter and mind which postulates the intervention of God to bring about in the one a change which corresponds to a similar change in the other. The theory thus denies any direct interaction between matter and mind. It was expounded by Geulincx and Malebranche to avoid the difficulty of Descartes's dualism of thought and extension, and to explain causation. Thus mind and matter are to Geulincx only the "occasional" causes of each other's changes, while Malebranche, facing further the epistemological problem, maintains that mind cannot even know matter, which is merely the "occasion" of knowledge.