John L. Heilbron

"Kuhn had the genius to find the words and sketch the concepts that made important old philosophical problems relevant to the public and newly discussable by philosophers. He had the strength of mind and commitment to lead the discussion. He could speak the truly incommensurable languages of physics, philosophy, and history, all necessary to frame and advance his epistemological quest. He wrote, as one of his admirers, Margaret Masterman, put it, in a "quasi-poetic style," sometimes veiled, sometimes with "rhetorical exaggeration," but always after careful and even painful thought. Or, to switch metaphors, he drew the portrait of science in the manner of the Impressionists. At a distance, where most viewers stand, the portrait appears illuminating, persuasive, and inspiring; close in, where historians and philosophers stare, it looks sketchy, puzzling, and richly challenging."

"Kuhns revolution was not yet a Kuhnian revolution, although he dated his intention to write the book that became Structure to the time of his wrestle with Aristotle. What he needed was a historical exemplar. He found it in the Copernican revolution."

"The physicists of Gilberts time had recourse to mechanism infrequently, and its effective explanations touched only a few disconnected phenomena. The virtuosity, inventiveness, and optimism of Descartes, however, and the counter-example of latter- day hermetists like Robert Fludd, persuaded many that mechanical models offered the only hope for a precise and comprehensible physics. Expectations rose. Physicists demanded more from models, perhaps even a complete fit with phenomena, with little or no negative analogy. Gilberts countrymen , diplomat and philosopher, and Thomas Browne, physician diplomat and literateur, freed his watery humor objections of Cabeo by concocting it into an unctuous, elastic vapor. Such a vapor could allow Cabeos rebounds, occasion the reattractions of ricocheting that Digby noticed, and — in its elastic contractions — draw the electric as well as the chaff. This last inference was first made about 1660, by the unconventional Cartesian fellow traveller , S.J., a veritable giant in science and a liberal and candid physicist whenever his Societys obligation to combat Copernicans did interfer."

"Structure joins the evocative concept of paradigm, a disarmingly simple dialectic of scientific change (long periods of paradigmatic "normal science" punctuated by short "revolutions"), and the apparent authority of historical example to show that major conceptual shifts in the natural sciences are effected not by logical argument alone but also by appeals to worldviews, religion, metaphysical commitments, notions of simplicity and order, and so on. The view that science, like other thought systems, advances or retreats through rhetoric and persuasion, not by logical necessity, was a revelation to people who had never practiced it or studied its history. The book comforted social scientists who wanted to assimilate their discipline to physics, Luddites who blamed social problems on scientists and engineers, and everyone who rejected authority. It repelled the philosophers of science at which it was aimed for the good reason that it undercut their belief that scientific knowledge advances by the application of rational criteria to the products of observation and experiment."