Abstract

I argue that neither realist nor anti-realist accounts of theory-change can account for the transition from zymotic views of disease to germ views. The trouble with realism is its focus on stable and continuous elements that get retained in the transition from one theory to the next; the trouble with anti-realism is its focus on the radical discontinuity between theories and their successors. I show that neither of these approaches works for the transition from zymes to germs: there is neither continuity nor discontinuity, but, instead, a gradual evolution from zyme to germ views, during which germ elements are slowly incorporated into zymotic views until, eventually, none of the original zymotic constituents are left. I argue that the problem with both realism and anti-realism is that they rest on the unwarranted assumption that there are clearly delineated zymotic and germ theories as well as arguments for and against these theories, an assumption that does not hold.