How did Karl Jaspers move from medicine and psychology into philosophy?

Karl Jaspers’ transition from medicine and psychology to philosophy was driven by both academic opportunity and his evolving intellectual interests.1

In 1913, Jaspers joined the philosophical faculty at the University of Heidelberg as an empirical psychologist. While his move was partly due to the faculty's need for a psychologist, his work increasingly pushed against the boundaries of scientific inquiry. His 1919 publication, Psychologie der Weltanschauungen ("Psychology of World Views"), served as a pivotal bridge; while intended to define the limits of psychological understanding, it foreshadowed the existential themes that would define his later philosophical career.1

Jaspers eventually sought to develop a philosophy independent of science that could illuminate the totality of human existence. He moved away from viewing philosophy as a prophetic vision, instead focusing on the freedom of the individual as the center of reality. This intellectual journey culminated in the 1930s with the publication of his major works, including the three-volume Philosophy, establishing him as a leading figure in existential thought.1