Over the past few years, historians of Greek philosophy have become increasingly aware of the importance of the Greek medical tradition for the understanding of ancient philosophy. Of course, the voluminous medical literature of late antiquity, from Galen on, has long been recognized as invaluable as a second-hand source of information regarding the doctrines of philosophers, most notably those from the early Stoa, which have otherwise perished in the wreckage of history. But more recently scholars have turned to the medical writings as sources for philosophy in their own right. They have come to see the great epistemological debates that formed the core of Hellenistic philosophy as being prosecuted just as vigorously in the medical schools as in the groves of Academe. That debate is the principal focus of this paper: but it is worth first briefly sketching the long history of Greek philosophical medicine.

Among the earliest Presocratics, Alcmaeon of Croton (fl. c. 575 BC) was a man of both medical and philosophical interests, giving an account of the physiology of perception, and of concept-formation. A century later, Empedocles combined a reputation for abstract physical speculation with a certain réclame as a medical man, and he too was interested in cognition and perception. Equally, several early Hippocratic texts deal with philosophical questions concerning the nature of knowledge and explanation. Later doctors of importance to the development of philosophical methodology include Herophilus and Erasistratus (fl. c. 260 BC), Asclepiades of Bithynia (fl. c. 120 BC), and Galen.

But perhaps the strongest and most durable connections are those which developed between Empiricist medical epistemology and Scepticism.