§8. Ancient Medicine and Empirical Philosophy
'1 he physicians of antiquity were enjoined by their discipline to doubt, deny, hesitate, query, engage with the singular and exceptional, and seek sufficient rather than necessary causes.
Hippocratics introduce evaluations of imperfect or uncertain truth-values into medicine and natural philosophy: relative frequency, dominance, presence of error, inexactness, approximation, and inference from complex and incomplete evidence. In an early and consistent tradition, some of these doctors extol experience as the single source of medical knowledge, and disparage theories of unseen causes which, even if true, do nothing for medical practice, since good doctors continue to do what they have always done without philosophy’s blessing. '1 heir medical opponents, the first rationalists, make the same optimistic argument that Bacon, Boyle, and Gottfried Leibniz urge in the seventeenth century, namely, that theoretical knowledge of causes can be expected to enhance medical practice.69Hippocratic authors make readers aware of the difficulty of knowledge and the problem of error. They keep careful records of their observations, expect progress in their knowledge, and are not afraid to admit mistakes. If these seem like obvious virtues for natural philosophers, remember that neither Plato, Aristotle, nor their schools gave them any consideration. '1 his research ethic is the earliest form of the fallibilism associated with empirical philosophy. When William James (a doctor) explains his empiricism he leans on this tradition. “Objective evidence and certitude are doubtless very fine ideals to play with, but where on this moonlit and dream-visited planet are they found? I am therefore myself a complete empiricist so far as any theory of human knowledge goes.” Holding an opinion “as if it never could be reinterpretable or corrigible” is “a tremendously mistaken attitude, and I think that the whole history of philosophy will bear me out.”70
Hippocratic physicians pioneered the scientific concept of cause.
Our oldest idea of research method derives from their founder. '1 hese physicians are alert, their perceptions probing, their memory tenacious, and their experience extensive. They value inquiry, which any physician should be constantly carrying out both in patients and on the side. '1 he life of these doctors is committed to research as well as practice, indeed, research for practice, for the improvement not just of their own skill but of the art itself, the medical techne, a corporate body of progressive knowledge every doctor draws on.Alexandrian medicine preserves all of these qualities, sharpening the terms, deepening the scientific context in which the argument between empiricists and rationalists plays out. They introduce experimentation, including vivisection, and the first effort to quantify medical procedures, calibrating dosages and pulses with instruments and standard measures. Galen inherits all of these traditions. He is sympathetic to medical empiricism, but rectifies medicine’s concept of experience, which has to be qualified, supervised, controlled by a rational assessment of the conditions under which symptoms appear and remedies are applied. The experience from which a doctor learns something medically worth knowing is this qualified, methodically controlled experience. Medical practice is not improved by theory. All the technical knowledge a doctor requires is empirical and does not involve hypothetical causes. However, more is at stake than medical practice, for Galen is also a natural philosopher. Medicine is an art but also a science, and as a science medicine employs hypotheses referring to unseen causes, which require the methodological finesse of rationally qualified experience.
Galen’s position on the empiricism-rationalism question was decisive for the medieval phase of what eventually became the scientific revolution. His rule of qualified experience gives priority to experience, as empiricists wanted, while acknowledging disciplined, methodologically qualified reference to hypothetical causes, as rationalists wanted, yet experience remains the ultimate judge, and there are medical truths that only experience can discover. The philosophical tradition from Aristotle denied that a techne could have its own method and be the equal of episteme-science. For Galen, medicine is precisely such an art, and its methodical use of qualified experience is an independent source of natural science alongside the logical intellect. It will be more than a thousand years before philosophers finally pluck this fruit, and open a way past Aristotle to a more consistently empirical natural philosophy.