At the turn of the twentieth century, a number of philosophers introduced the idea of philosophical research on cognition that could enter into competition with psychology, which was developing into an autonomous discipline at that time. In view of the problems of the traditional but still prevailing associationist theory, Ernst Cassirer demanded a more sophisticated theory that could explain the human ability to concentrate one’s thoughts on a topic, such as a problem or a task. He presented a representational theory of mind to explain this ability. This paper explicates the scope of this theory and Cassirer’s idea of interdisciplinary cooperation between philosophers and psychologists.