Neither the title nor the subtitle of this book really previews its contents, although Wray uses a historical backbone that follows Kuhn’s career and the development of his ideas. A better title might have been “What Kuhn Really Said,” as Wray’s goals are both to document Kuhn’s actual positions as they developed over his career and also to explode myths and counter fallacious appropriations of Kuhn. The current book adds to Wray’s very important monograph Kuhn’s Evolutionary Social Epistemology (2011), two major collections Interpreting Kuhn: Critical Essays (2021) and Kuhn’s The Structure of Scientific Revolutions at 60 (2024), which he edited and contributed to, and numerous articles. This body of work has made Wray the most important contemporary scholar of Kuhn and his ideas. Wray’s account of Kuhn is both accurate and precise.

Wray begins with a largely chronological account of Kuhn’s intellectual debts. An opening chapter examines Kuhn’s 1947 “epiphany” when, as he later put it, “… all at once Aristotle seemed a very good physicist indeed, but of a sort I had never dreamed possible” (Kuhn Reference Kuhn1987/2000, 16). Wray finds here the origin of Kuhn’s recognition that his earlier thinking had been anachronistic and that he needed actors’ categories to understand the work of historical figures. At the same time, the scale of Aristotle’s system, and the recognition that it differed from Newton’s categories at the most fundamental levels, started Kuhn on the path to the concept of a paradigm and correlative ideas of revolutions, incommensurability, and the non-cumulative growth of knowledge. However, Wray emphasizes, none of this led Kuhn to relativism about the history of science, an issue that Wray returns to repeatedly throughout the book. This first chapter prefigures much that will appear later, except the things Kuhn had yet to work out in 1947: the positive function of revolutions in the growth of knowledge, how science works between revolutions (normal science), and how all this fit into a cyclical pattern.

The next three chapters present Kuhn’s debts to James B. Conant, the history of chemistry and logical positivism. The Conant chapter is still the longest sustained examination of Kuhn’s relationship to one of his most important precursors. But although Conant talked suggestively about conceptual schemes and indeed revolutions, Wray shows that Kuhn does not simply borrow or elaborate on Conant. His corresponding concepts are radically new, as shown by the things missing in Conant’s history of science: normal science, non-cumulative growth of knowledge, fundamental entities that vanish during revolutions, and, of course, incommensurability. Wray also uses Conant’s chapter to introduce another fundamental but misunderstood theme in Kuhn, that the community, not the individual, is the actor in scientific change.

In chapter 3, Wray shows how teaching the history of chemistry provided Kuhn with examples that made Lavoisier and his contemporaries more important than Aristotle in the development of his major ideas. In chapter 4, Wray wades through the morass of logical positivist attempts to dismiss or co-opt Kuhn, for example by claiming a kinship to Carnap. Despite Kuhn’s later self-denigration, Wray shows that he had a sophisticated knowledge of logical positivism, probably mediated by Quine. Kuhn clearly believed that logic-based analysis was incapable of revealing or representing many key features of science, from analogical inference to incommensurability.

Next, Wray discusses Kuhn’s immediate influence on the social sciences and the origins of the Sociology of Scientific Knowledge (SSK) movement. He then turns to Kuhn’s relations to the history of science, and to philosophy, including another of Wray’s special concerns, the contemporary realism/anti-realism debates (see his Resisting Scientific Realism, 2018), where he finds that Kuhn conditioned the debates, but did not really participate. About the social sciences it would be fair to say, echoing Kuhn’s judgment that they failed to achieve the consensus needed to install a paradigm and begin normal science, that the same fields also failed to achieve a consensus on how to appropriate Kuhn. The SSK movement, however, knew exactly what they wanted from Kuhn—a history of science that was not only non-cumulative but completely relativist. Kuhn immediately and strongly denied this reading of this work. Wray accurately locates the root of the SSK misreading in the bizarre idea that every new application of a concept is undetermined by previous use. This generalizes one limited feature of Kuhn’s account of scientific creativity to the whole of science, and would make both scientific education and normal science impossible. But the damage had been done, and many philosophers read the sociologists as confirming their worst fears about Kuhn. Wray explains at length where both the sociologists and most philosophers went wrong. Kuhn is not a relativist but, as he put it himself, a neo-Kantian with revisable categories. Revolutions are non-cumulative; fundamental entities may disappear and, after a revolution, concepts may be used in ways that were formally forbidden before the revolution (e.g., Lavoisier: air is a mixture; metals are elements). But this neither creates universal failure of communication between paradigms nor prevents their rational evaluation. Kuhn believed that the science we have now is better than any science we have had before, and demonstrably so, just not in the ways that logic-based philosophy of science wanted. A concluding chapter on Kuhn’s career after Structure gives highlights from Kuhn’s mature work, especially his ongoing attachment to a theory of concepts that functions without necessary and sufficient conditions for class membership.

Who should read this book? Anyone who is interested in Kuhn’s ideas, or historically oriented philosophy of science in the second half of the twentieth century, will find many things of value here. But a much larger audience would benefit from reading it. If you are an analytic philosopher, and especially if you are a philosopher of science, what you believe about Kuhn is probably wrong, and this book will begin to set you right. If what you believe about Kuhn is wrong, what you believe about science is wrong too. Science is our paradigm for rational discourse and the creation of knowledge, so if you don’t understand what Kuhn said about science, then you have no business theorizing about rationality or knowledge. There is a great deal of work to do, and Wray’s book is an excellent place to start.