Manuscripts: Norwood Russell Hanson's Referee's Report on "Structure"

[The Referee is Norwood Russell Hanson]



          I begin by apologizing, to the University of Chicago Press and to Professor Kuhn, for my tardiness. As Mr. Bowen knows the MS. reached me while I was caught up in summer business at Oxford, Cambridge, and Colorado. This is by way of explaining, although not justifying, the delay I have caused you all to suffer. Please forgive me. The situation is exacerbated by all my notes, lectures -and indeed, Professor Kuhn's MS. -- being 'lost' somewhere between London and Bloomington. But the work is sufficiently fresh in my mind to allow reconstruction of my comments.

     Kuhn's is a work of surpassing merit, scholarship, and creative ingenuity. This is the point of this report. On that point, however, hangs both the strengths and weaknesses of the manuscript. The weaknesses do not require extended revision. But their nature should be set out here, else they will certainly be set out in reviews.


          It is on the idea of a conceptual paradigm that Kuhn's theses hinge. Although this is nowhere set out explicitly Kuhn's conceptual paradigms are not unrelated to what other historians of science have called "framework principles." It is a framework principle of Newtonian Mechanics that every state of a physical system is predictable and retrodictable from its present state via the known laws of mechanics. Accordingly, the 'state' of a punctiform mass should both be consistently describable and extrapolable into the future. This distinguishes classical mechanics from contemporary microphysics. Thus, complete determinability of particulate states within classical mechanics constitutes a framework principle, and any challenge, attack or revision at that point constitutes the challenging of a paradigm. Quantum mechanics challenges that paradigm, and to that extent rests on, and constitutes, a scientific revolution. Similar examples are easily proliferated. In short, Kuhn's conceptions of (1) scientific revolutions and (2) the challenging of paradigms are inextricably interconnected.

          Now this is illuminating. It makes it clear that scientific revolutions have something in common; to wit, the challenging of earlier paradigms. Changes within the history of science which consist in less than this are not genuinely revolutionary. Thus, the invention of a new laboratory technique, or the discovery of a new natural object, these will not per se constitute part of a scientific revolution. The latter, like science itself, is effected primarily at the conceptual level. Kuhn's treatise leaves no room for doubt on this.

      Consequently, Professor Kuhn's achievement is to establish for the reader that scientific revolutions are conceptual revolutions. The great advances in the history of science have been advances in ideas. This point has been made before – but rarely with so rich a tracery of detail and allusion. Thus the strength of Kuhn's book. Thus also its weakness. For the most probing question to put to this historian is this: what precisely would Kuhn allow as a possible counter-instance to his thesis? Historical theses are contingent. They are informative; they tell us what in fact is, or has been, the case. They are not compatible with everything and anything that has or could happen. Their informative content is logically connected with what they are denying -- with what they exclude. A thesis that fits everything thinkable says nothing. In short, historical theses must be in principle falsifiable if they are to convey to us something we didn't know.

          Is Kuhn's thesis falsifiable? For Kuhn: Is the thesis (if it is a thesis) that all scientific revolutions are the result of the overthrow of a paradigm* -- is this falsifiable? The Janus-faced 'strength-and-weakness' of Kuhn’s book is that, in the process of interrelating the idea of a scientific revolution with that of a conceptual paradigm, he virtually makes these inter-definable terms. To understand what Kuhn means by "a scientific revolution" one has got to introduce the notion of "an overthrown paradigm" as a semantical component of the original expression. And what precisely is an overthrown paradigm? That's easy -- it is the kind of event which generates a scientific revolution! So what began as flexible link ends as a rigid weld. For Kuhn, it appears that the claim "scientific revolutions result from overthrown paradigms" is either circular or tautological. It is circular if it purports to convey factual information but so inter-defines the component terms that the reader's attention is not directed beyond the claim itself. It is tautological if, when confronted with possible exceptions the thesis achieves its certainty by retreating 'definition-like' into complete invulnerability.

          My suspicion, and others will react similarly, is that Kuhn has overplayed his hand somewhat. One's impression is that if his thesis were put to the test in a crucible of strong counter-examples, that thesis would envelope and agglutinate every apparent exception. My impression is that if I got Kuhn to agree that P1 P2 and P3 were all /paradigms or /framework principles', and to agree also that these have been effectively overthrown -- if after he agreed with all this I then sought to indicate that subsequent events did not constitute what ordinarily is called a "scientific revolution," Kuhn would simply baptize the subsequent events as being such a revolution. If, on the other hand, one entertains something which has come to us through history described as a "scientific revolution", but where no P1 P2 or P3 has been overthrown, then here Kuhn would simply deny "the considered verdict of historians"; he would deny that it was a revolution at all.

          The important thing about genuine empirical hypotheses is that, although it is understood what events could reveal them to be false, they nonetheless often turn out to be true. Kuhn's thesis would be more arresting as an historian's empirical claim if, although he and we could cite possible events which (had they but obtained) would falsify his thesis, yet nonetheless the thesis is in fact historically true. When a scholar so strengthens his darling-hypotheses that he wants to make them completely invulnerable, it becomes no longer possible to understand what empirical, or historical state of affairs he really seeks to illuminate. It is no good taking the high tone historians sometimes do: "oh well, from a logician one expects logic chopping." For, if there is any truth in the foregoing objection at all, Kuhn's main thesis suffers profoundly and the remaining virtues of the book must be judged to reside entirely in the rich wealth of examples which he serves up inter alia.

          Yet, it seems clear that Professor Kuhn can, in a single stroke meet this objection, fortify his argument, guide his readers, and assuage his future reviewers. He can simply write up a few paragraphs indicating what, in his opinion, would or could falsify his main thesis. Unless he does this he has not shown us in what sense his book -- besides being interesting, refreshing, ingenious and imaginative -- is also true.


(*Is this really the same as: all overthrows of paradigms result in scientific revolutions?)


          But even should Professor Kuhn, and the Editors of the University of Chicago Press fail to entirely endorse the criticism tendered above, I would still heartily recommend publication of this book. As it stands it is specifically brilliant, but generally unconvincing. There is the best precedent for placing a book with these particular properties before the learned reading public. I beg only that the University of Chicago Press, and Professor Kuhn, consider an adjustment which would make the setting of his argument as sound as are the historical gems Professor Kuhn has mounted in that setting.


[In staccato fashion I will address briefly the questions set out on your "Advice To The Reader sheet.]

          Concerning what the author has accomplished -- I think I have made this clear. Kuhn has established what his predecessors have intuited or only vaguely suggested; to wit that great upheavals, high points, and new directions in the history of science are effected within the realm of ideas. Since this itself constitutes a thesis which spans history of science and philosophy of science, our major criticism developed earlier must be one to which Kuhn’s book is vulnerable. Concerning other books on the same subject, I doubt that any exist per se. This is usually the kind of thing about which scholars make passing remarks in their obiter dicta or at non-professional international meetings. Kuhn has addressed the subject seriously and with scholarly power.

          I have spoken to the originality of this work. I have indicated, I hope, that the historical scholarship seems to me, and will seem to most historians of science, very sound indeed. The Manuscript is important. I would envisage a large audience consisting of scientists, historians, philosophers, and a well-educated public purchasing this book. Its use in under-graduate classrooms is something about which I would be somewhat less confident, but not wholly pessimistic.

          The style is the man. Kuhn is himself an intricate embroidery of learning, interest, skills and passions. His book is no less intricate and no less an embroidery. I have already indicated that the overall structure loses some force and clarity in the midst of all this detail. And Professor Kuhn will grant as readily as I will assert that some of his sentences are too long, some are too short, some are ponderous and Teutonic, and some are startlingly abrupt. But to say this is no more than might be said of one's own work, and I would no more want Tom Kuhn's book to read like Fowler than I would like Tom Kuhn himself to look like Achilles or Christ. THE STRUCTURE OF SCIENTIFIC REVOLUTIONS is neither an Iliad nor a Bible. It is a good piece of work in history of science and its style is suited both to the man and to his objectives.


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