The histories of philosophy and medicine in the ancient world are deeply intertwined. Some individuals we think of as philosophers had serious medical interests (Empedocles and Sextus Empiricus, for instance); rather more doctors exhibited a more than merely avocational interest in philosophy (Alcmaeon, Diocles of Carystus, Herophilus, Erasistratus, Asclepiades, Menodotus, and preeminently Galen). The treatises of the Hippocratic corpus are full of philosophy; and both Plato and Aristotle paid due attention to medicine.

Perhaps the most important single instance of the cross-fertilization of ideas between physician and philosopher consists in the great debate about the nature of science and the limits of epistemology conducted with equal vigour between the skeptical schools and their medical colleagues the Empiricists (and later the Methodists) on the one hand, and the various Dogmatic sects of both philosophy and medicine on the other. Indeed, even the terminology is revealing: anti-theoreticians in both the medical and the philosophical camps standardly refer to their opponents as Dogmatists.