Are there any scientific revolutions? Such a question has been raised by some of Kuhn’s critics. Larry Laudan (1984), for example, argues that no changes in science are aptly described as revolutionary. Laudan claims that given Kuhn’s holistic account of paradigms a revolutionary change involves simultaneous changes in methods, goals, and theories. But, according to Laudan, Kuhn’s holism “leads to expectations that are confounded by the historical record” (84). Laudan argues that all changes in science are continuous enough with the traditions preceding them to make calling any of them “revolutions” inappropriate. The only reason one would be led to believe otherwise, he claims, is if one fails to look at the process of change in sufficient detail. This same criticism, which challenges the very existence of revolutions in science, was also raised earlier by Stephen Toulmin. Writing in the 1960s, Toulmin claims that “students of political history have now outgrown any naïve reliance on the idea of ‘revolutions’ ” (1970/1972, 47). Similarly, he argues, “the idea of ‘scientific revolution’ will have to follow that of ‘political revolutions’ out of the category of explanatory concepts” (47).

My aim in this chapter is to address this criticism. I aim to show that there really are Kuhnian revolutions in science. In an effort to argue my case, I will show how the concept of a Kuhnian revolution provides insight into the change that occurred in early modern astronomy, a change that has come to be called “the Copernican revolution.” In addition to showing that there are in fact scientific revolutions, I will demonstrate the value of the concept “scientific revolution,” and the aptness of Kuhn’s comparison of theory change to radical political changes. This case study is also important because this particular historical episode was important to Kuhn’s own thinking about scientific change. Five years before the publication of Structure Kuhn published a book-length treatment of the Copernican revolution in astronomy. This book was published without the benefit of the detailed account of theory change Kuhn presents in Structure. Consequently, Kuhn’s pre-Structure study of the Copernican revolution is rather unKuhnian in some respects. Further, given that Kuhn revised his understanding of scientific revolutions, it is important to determine the extent to which this episode fits Kuhn’s developed account of revolutionary change, the account articulated in the previous chapter.