In the previous chapter, I indicated that one of the things we need to understand better is how a new theory comes to displace an older theory. In particular, I indicated that we need to develop a better understanding of the social dimensions of changes of theory. I also suggested that sociological studies of science may be illuminating in advancing our understanding of how the process of theory change unfolds. After all, a change of theory not only involves the development of a new scientific lexicon, it also involves the acceptance of the new lexicon in the research community. For this to occur, an accepted lexicon must be abandoned.

In this chapter, I want to begin to investigate how a long-accepted theory gets replaced by a new theory in a research community. I want to start, though, by briefly examining some of Kuhn’s speculations on the process, in particular, his speculations about (1) the role that younger scientists play in the generation of a new theory, and (2) the role that older scientists play in the acceptance of a new theory. Then, I want to review some evidence that suggests that Kuhn’s speculations are mistaken. Finally, I want to examine a particular episode of theory change in the history of science in an effort to develop a better understanding of the nature of the social changes that occur with a change of theory. The object of my study will be the revolutionary change in geology in the 1960s that led to the acceptance of the theory of plate tectonics.