Biology and Philosophy 13: 1–4, 1998.c 1998 Kluwer Academic Publishers. Printed in the Netherlands.

Tom Kuhn – An Appreciation

PHILIP KITCHERDepartment of PhilosophyUniversity of California at San DiegoLa Jolla, CA 92093U.S.A.

In the late 1960s, any aspiring British undergraduate looking to study thephilosophy of science would have been told just where to go. Princeton wasobviously the place, the academic home of C.G. (“Peter”) Hempel, well-known as an extraordinary teacher and “the dean of philosophers of science”(the standard Cambridge description). But Hempel was by no means theonly attraction. There was also T.S. Kuhn whose slender monograph, TheStructure of Scientific Revolutions, published only a few years before, hadalready excited a wide-ranging discussion.

Those who arrived at Princeton expecting to find Kuhn giving regularseminars on his controversial theses were destined for disappointment. Tobe sure, Kuhn was giving graduate courses, wonderful courses on the grandsweep of the history of western science up to the early modern period, but hewas reluctant to offer the philosophy seminar to which his name was attachedin the Princeton catalogue. According to popular rumor, he was unhappy withthe cut-and-thrust of minute arguments, in a context in which his interlocutorsseemed unsympathetic to his big ideas and entirely ignorant of the historicalbackground to them. If the Kuhnian view was that advanced in SSR, then itseemed only possible to study it with him indirectly.

That reticence was entirely typical of Kuhn’s attitude to his most famousbook. Critics and would-be Kuhnians alike often found that he was unhappywith the theses ascribed to him. Now, more than three decades after the originalpublication, it is easy to understand why, to recognize how the making definiteof ideas that were carefully balanced, delicately nuanced, and, sometimes,blurred could appear mistaken, even offensive. In the 1960s and 1970s, Kuhnwas linked with Paul Feyerabend, and the two of them seemed intent on aform of irrationalism, the glorification of “mob rule” in science, the advocacyof relativism. Properly brought-up philosophers wanted none of it, and scoresof analytically-trained graduate students sharpened their swords to attack the

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dreadful dragons. Meanwhile, at the other end of the corridor, historians andsociologists were making a takeover bid of their own, apologizing for thepassages in which Kuhn seemed to retreat from his most startling claims, andadvertising themselves as Kuhnians (later as post-Kuhnians). Like Mercutio,Kuhn found himself in an extremely difficult position.

Through the last decades of his life, he attempted to solve the problem in avariety of ways: returning to history, then collecting some extraordinarily richand stimulating essays (The Essential Tension), writing a long-promised bookon the early history of quantum theory, turning to analytic philosophy (afterthe move to MIT), and always struggling to rearticulate the doctrines of SSR.Many audiences have heard lectures, brilliant and provocative presentations,that went over Kuhn’s central themes from a variety of new perspectives,but he was not satisfied. Potential misinterpretations continued to haunt him,although he surely took comfort from Paul Hoyningen-Huene’s extendedarticulation and defense of his ideas.

Everybody knows the central plot line of SSR. Science begins as pre-paradigm chaos gives way to the acceptance of a paradigm that defines atradition of normal science. Normal science is primarily puzzle-solving, andthe daily work of science tests the scientist, not the paradigm. Ultimately, oneor more of the puzzles proves recalcitrant, becoming seen as an anomaly (oranomalies), and the field enters a state of crisis. Once again there is debateabout fundamentals and the entrenched paradigm may conflict with proposednew paradigms. If one of these is accepted, then the resolution cannot beby the kinds of rules recorded in traditional logical empiricist philosophy ofscience. Proponents of different paradigms are at linguistic cross-purposes,they do not agree on their observations of the world, they make different valuejudgments about the importance of particular problems and achievements –they live in different worlds. After a change of paradigm, a revolution, theworld changes, and although some things seem to be retained, there is nocoherent direction of development. The growth of science is like the historyof life, evolving without any obvious criterion of progress.

In many ways it is a simple plot, and the simplicity is part of the explanationof the book’s enormous success. But only a part. As one reads and re-readsthe individual sentences, there are always new resonances, suggestions of athesis more complex than that one had attributed. Returning to the book againand again over the past twenty five years, I have never read it the same waytwice – and that, too, is an important factor in its influence. We think we knowwhere Kuhn stands, until we find him in a slightly different place. Those whocondemn – or celebrate – Kuhn the irrationalist (to cite just one example) canfind much material in Section XII, reading of “conversion experiences” and“decisions that can only be made on faith”, but then they reach the bottom of

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p. 158 and a paragraph in which successive sentences seem to retract whathas just been granted. There are many simple Kuhns, but they all turn out tobe cartoons.

So, reflecting on what scholars have done with SSR, it is hard to suppress asense of embarrassment. The critiques of the 1960s and 1970s, which seemedonce so powerful, appear flat and dated against the freshness of Kuhn’s ownprose and the subtleties of his ideas. The enthusiasms of would-be Kuhniansare equally inadequate, often foisting on to him theses that are denied byhis writings. In the end, there appear to be two possibilities. Perhaps thereis simply no consistent position to be reconstructed; or perhaps SSR offersan insightful account of many aspects of scientific practice, an account thathas been much misunderstood, and that Kuhn struggled to articulate moreextensively.

Whichever of these possibilities is the right one, Kuhn changed our world,the world of philosophy of science. Although his training in physics promptedhim to gravitate to the physical sciences for inspiration and examples, thereis no doubt that current work in the philosophy of biology draws on his ideas.Precisely because of the rich suggestiveness of SSR, I suspect that Kuhn willcontinue to be read long after the time at which virtually all the philosophyof the past decades is mouldering on the untouched stacks of library annexes– and that future scholars will continue to construct new Kuhns to embodytheir favorite (or least favorite) ideas.

I want to close this brief essay with some words about Tom Kuhn, theman. The first thing that struck his students was the extraordinary energy: itseemed that the intensity of his thoughts had to find expression in the rapid-fire delivery or in the vigorous gestures. Listening was immensely exciting,especially given the seriousness with which he took questions. Tom was alsocapable of great warmth and sympathy, able to reach out to people in troubleand to offer them support. (But for Tom’s efforts, I would never have gone toPrinceton, and but for his support, among others’, I would never have beenable to remain there.)

Most vivid for me is the extraordinary intellectual honesty, the dedicationto working things through and getting them right, so at odds with the facilerelativisms often attributed to him. Tom was never convinced by the attrac-tiveness of a solution generated in discussion. I recall numerous occasions onwhich, after an afternoon seminar or a strenuous discussion, he would call atemporary halt, insisting on his need to think the points over and then, the nextday, he would come back with a new perspective, determined to continue theprocess. He must have known from his youth that it was easy for him to beclever. Being right was far harder – but only that was ultimately satisfying.

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Thomas Kuhn19 –1996