Thomas Kuhn published The Structure of Scientific Revolutions in 1962, over 60 years ago. The book is principally remembered for the role it attributes to paradigm change in the development of science. On Kuhn’s account, the growth of scientific knowledge follows a pattern; periods of normal science, characterized by widespread consensus, are interrupted by paradigm changes, where the prevailing consensus breaks down, and a new consensus emerges around a new, fundamentally different, paradigm or theory. Kuhn insisted that even our best scientific theories have a limited lifespan. At some point, they become obsolete and an impediment to further scientific advances.
On the one hand, there is nothing especially threatening about this picture of science. As human constructions, it is not surprising that our scientific theories have their limitations and need to be replaced. On the other hand, the picture of science that Kuhn presents seems to threaten a widespread image of science. Many people, including many scientists and philosophers of science, think of science as a march ever closer to the truth, with no significant setbacks, and certainly in no need of fundamental changes in our conception of what the world is like. The growth of science, many claim, is principally a matter of refining and extending the application of the long-accepted theories.
There are many suggestive insights in the book that captured the imagination of scholars in a range of disciplines, including, philosophy of science, sociology of science, economics, political science, and anthropology. The paradigm concept has taken on a life of its own. It was thoroughly criticized for its apparent imprecision early on by philosophical readers of Structure. It was eagerly embraced by many social scientists who saw it as a key to understanding their own disciplines. And it has made the transition from an analysts’ term to an actors’ term; it is now commonplace for scientists to write about the paradigms they are working with in their research.
Philosophers of science have tended to focus on the threat posed by Kuhn’s account of science. Many were not satisfied with Kuhn’s account of how the choice between competing theories is resolved. On the one hand, Kuhn acknowledged that the traditional values that concern philosophers of science — simplicity, predictive power, empirical adequacy, and such — play some role in this process. But he also insisted that these values often do not unequivocally favour one theory over another, especially in the early days of an impending scientific revolutions. To many readers, Kuhn seemed to be suggesting that theory choice was not a wholly rational process.
Kuhn also claimed that scientists consider the fruitfulness of theories when choosing between competitors. The fruitfulness of the theory concerns the future promise of a theory. If Kuhn is correct about this, scientists do not just judge a theory by its past performance, by what data it can account for. Rather, in choosing to work with one theory rather than its competitor, scientists are predicting a theory’s future success in solving hitherto unsolved research problems.
Philosophers of science have been reticent to accept Kuhn’s account of theory choice and the appeal to fruitfulness. For anyone trained in the tradition of the logical positivists who were concerned with modelling the logic of theory choice, fruitfulness is quite elusive. But, before we dismiss Kuhn’s appeal to fruitfulness as a criterion of theory choice, it is worth remembering that Kuhn first encountered the notion of fruitfulness while working as a teaching assistant for James B. Conant. Conant was an accomplished chemist, the president of Harvard, and involved in the Manhattan Project, which led to the development of the atomic bomb.
Though many philosophers of science still hold Kuhn’s Structure at some distance, many others have found fruitful ways to build on Kuhn’s insights. The renewed interest in Kuhn’s account of scientific change has been driven in part by the excellent historical scholarship in Kuhn studies that has developed over the last two decades. Many scholars working on Kuhn have drawn on the rich resources in the T. S. Kuhn Archives at the Massachusetts Institute of Technology in an effort to understand what was influencing Kuhn at different stages in his career, and where he was going as he tried to complete his final book, the successor to Structure. This new scholarship has led to both externalist explanations, explanations that look at the culture milieu in which Kuhn worked, and internalist studies, studies that emphasize the influence of concepts and theories of science on Kuhn’s thinking. Not only was Kuhn working during the early days of the Cold War, he was working with Conant, someone who was at the forefront of shaping America’s post-World War II scientific policy. So it is not surprising that this would affect Kuhn’s understanding of science. But he was also developing his view against the background of the then-orthodox view, some form of Logical Positivism.
As the brief discussion concerning assessments of the fruitfulness of a theory reminds us, it is difficult to predict the future. But shortly after Kuhn’s death in 1996, the distinguished philosopher of science David Hull dared to predict the future impact of Structure. Hull claimed that “I suspect that a hundred years from now, Kuhn will be one of the few philosophers of science who will be looked back upon as having radically changed our understanding of science” (Hull 1996, 204).
Given Hull’s assessment, I think those who have read Structure in the past should revisit the book, especially in light of the new scholarship on Kuhn. And those who have not yet read it should not be put off by others’ concerns about the threat Kuhn’s theory of science seems to raise. If Hull is right, one would hate to have not read the book, at least once.