One of the most striking forms of scientific change is the rapid and seemingly endless growth of new scientific specialties. Nicholas Rescher (1978) notes, for example, that the number of specialties in physics has grown from 19 in 1911, to 100 in 1954, and reaches 205 in 1970 (229, table 3). Philosophers of science seldom discuss this dimension of scientific change. Specialization has been neglected by philosophers, in part, because they have tended to emphasize the value of unification in science (see, for example, Friedman 1974; and Kitcher 1993). Unifying theories deepen our understanding of the natural world by revealing connections between otherwise disparate phenomena. Specialization seems antithetical to this goal. Specialization can and often does create barriers between scientists. Thus, for many philosophers, specialization is seen as either an impediment to developing unifying theories or a temporary resting state along the way to developing unifying theories.

In chapter 1, in the brief discussion of the discovery of x-rays, we saw that theory replacement is not the only response that a research community has when it encounters persistent anomalies. Sometimes, as Kuhn notes, anomalies are dealt with by creating a new scientific specialty, a new research community that has as its concern the study of the previously anomalous phenomena. Further, the creation of new specialties is by no means a temporary state in the development of science. Rather, as Kuhn claims, specialization often serves to advance our epistemic goals in science. Hence, philosophers need to develop a better understanding of the role and effects of specialization in science.