The “Tragedy of Cambridge Economics” and Other Stories

It's Not All in Marshall

In mid-February 1938, J. M. Keynes received a letter from Richard Kahn, at the time a member of the Cambridge Faculty Board of Economics and Politics, on the reform of the Economics Tripos, the honors degree introduced by Alfred Marshall in 1903. The faculty were in general agreement on its defects and the pressing importance of revision. On the question of what to do, they could not reach consensus despite recognizing that Cambridge was losing ground. As Keynes replied,

Cambridge economics had reached an “awkward age, when the very fact that it started first” had become a “handicap.” In a troubling comparison, he suggested that “like some of the pioneer staple industries,” Cambridge was at risk of experiencing both the triumphs and the tragedy of a first market mover: the conditions that originally had made it successful now spelled failure (Keynes's notes on Tripos reform, 5/16/1938, JMK/UA/5/4/104–109).

Keynes's assessment of Cambridge economics in the late 1930s anticipated by more than eighty years a main theme of Keith Tribe's latest book, Constructing Economic Science: The Invention of a Discipline, 1850–1950 (New York: Oxford University Press, 2022).¹ How and why, he asks repeatedly, was economics transformed in the early twentieth century from political economy, a civic discourse validated by its place and performance in the public sphere, into economic science, a university discipline produced by social mechanisms of self-construction and self-validation: a “special kind of knowledge requiring no legitimation other than a mastery of its techniques” (18)? Constructing Economic Science (CES) is intended as a book “with a clear object,” its conclusion a “denouement that follows from the argument and evidence that has gone before.” A single objective, one argument, and one conclusion (xiii). Yes and no. Tribe plays numerous variations on the central question, posing and undertaking to settle a formidable array of questions.

Why did the “twin processes” of Disziplinierung (disciplinization) and Verwis-senschaftlichung (scientification) that created economic science first gain traction in Britain? Why not in Germany, where political economy had been established as an academic field in the major universities and Handelshochschulen since the third quarter of the nineteenth century? Or why not in the United States, where there were departments of economics and doctoral programs in important research universities? Why was Cambridge the first mover? As Tribe notes, the archaic structure of Cambridge—a newer organizational system grounded in faculty research specializations borrowed from German universities and awkwardly grafted onto the medieval organization of the self-governing colleges—made this improbable. Why not another British university such as Manchester or Birmingham? Or an American business school such as Wharton? Indeed, why not Oxford, a question to which Tribe devotes an entire chapter? Why was it that “the kind of innovation that Marshall made at Cambridge could not have been made in contemporary Oxford” (173)? And although Cambridge was the first, why was “the Cambridge moment” nothing more than “a passing episode” (173)? Why did the advances of Verwissenschaftlichung stall at Cambridge, inevitably, as Tribe seems to argue? As he plots the rise of economic science, “Marshallianism” “hardly outlived” Marshall's death in 1924. “By the 1930s it was already superseded,” even “relegated to a prehistory by an emergent economic science divorced from substantive connection with the ‘ordinary business of life’ that was at the centre of Marshall's concerns” (141). How did it happen that, in the 1920s, “disciplinary initiative quickly moved away from Cambridge” (173) to the London School of Economics (LSE)? What were the decisive factors that made LSE the primary British innovator in producing and reproducing economic science?

Tribe pursues these issues along two narrative tracks. Chiefly written as a single master narrative, the book is an “institutional chronology” of economic science as well as “a ‘genealogy of neoclassical economics’”: an account of the “Whig history” written by its “new incumbent practitioners,” exploring the forces that “moulded the development of a science whose practitioners subscribe to the illusion that their own ideas are, by virtue of being products of a progressive science, superior to the ideas of their predecessors” (18–19). Woven into the master narrative is an elaborate and discontinuous set of metanarrative remarks in which Tribe instructs readers on how to understand the master narrative. In these observations, sometimes confusing because of their occasional and casual quality, he anticipates, revisits, elucidates, and restates his intentions. Repetition is perhaps the definitive rhetorical quality of the book, in which the author leads readers from one economics faculty and commerce college to another as he makes his case. The longueurs of accumulating detail are not lost on Tribe himself. In a note to readers, he assumes that notwithstanding the importance he ascribes to the master narrative, it may not be read (xiii–xiv). Thus we have his frequent reminders in later chapters of what has been read and forgotten earlier or perhaps not read at all. Although an annoyance for readers who have no interest in a collection of textual modules, they do not seem to diminish Tribe's signal accomplishment: a breathtaking performance of compression, reduction, and synthesis of a massive body of research conducted over many years, a task that would seem to exceed the powers of a single scholar.

CES is a major contribution to the history of economics that repays careful study and merits a disciplinary conversation. The present essay initiates this dialogue by considering four of Tribe's main themes and analyses: his explanation of Disziplinierung and Verwissenschaftlichung; his conception of Marshallianism; his claim that Marshall's achievements at Cambridge would not have been possible at Oxford; and, in rather more detail, his argument that the early Cambridge ascendancy was compromised by fundamental institutional flaws, as a result of which it was eclipsed by LSE by the late 1920s and 1930s.

It's All in Max Weber?

In arguing that Cambridge initiated the dynamic of Disziplinierung and Verwissenschaftlichung that created economic science, Tribe calls for a radical departure from standard narrative practices in the history of economics employed in the Anglophone sphere. If “institutions made ‘economics’ what it is today” (5), the orthodoxies of the history of economic thought and rational reconstruction are useless for his purposes. More often than not, the predictable clichés—“ideas in context” or “contextualization”—“turn out to mean nothing more than ‘other ideas’” (369). A putative historiography of rational reconstruction is arguably even more flawed because of its teleological assumptions and “presentist bias” (369), reading the economics of the past from the standpoint of ideas and methods currently regarded as sound.

Employing narrative strategies that are now standard in science studies, Tribe conceives CES as an oppositional “historical reconstruction” of the mundane underpinnings of economic science, the “material context” or material culture that formed the original institutional conditions without which neither economic science in any sense nor the development of economic theory, high or low, would have been possible. In this reconstruction, the following elements, which are both logically and historically interdependent, prove to be most significant: (1) the dual role of economists as teachers—producers of students certified by examination as academically trained—and researchers who are certified as competent by publication in disciplinary journals; (2) a standardized pedagogical regime of syllabi, texts, and written examinations, performance on which decides success or failure in academic rituals of certification; (3) a division of labor produced by specialized research cast in an increasingly arcane language differentiated from the parlance of public discourse; (4) a predictable supply of students and methods of financing; (5) an academic labor market in which specialists compete for positions, a selection process of winnowing that determines who is granted professional salvation; (6) a disciplinary ethos defined by a culture of careerism that selects in favor of those who perform best in meeting disciplinary-specific expectations. Satisfaction of these six conditions by an emergent discipline forms a seventh element and is the basis of a disciplinary theology of self-validation, produced tautologically on the grounds of its own technical and methodological logic.

Not differentiated in CES, elements 1–6 constitute what Tribe calls Disziplinierung; element 7 identifies Verwissenschaftlichung. Although they are the two pieces of conceptual apparatus that bear most weight in the book, he offers little by way of analysis of either. “Discipline” is defined in an early footnote (3–4). However, the “twin concepts” are never elucidated, and in making a case for his institutional chronology and the precedence of “non-cognitive conditions of the existence of knowledge” over “epistemologies” or an “epistemological perspective” (18–19), he handles the evidence for his Disziplinierung criteria with a light touch. In some one hundred pages of discussion on Cambridge (75–176), there is little evidence that the early Economics Tripos in fact met these conditions. For the most part, he tries only to show that this is what Marshall meant to achieve. To clarify Verwissenschaftlichung, he directs readers to Lutz Raphael's (1996) lengthy article in German. However, there is no analysis of Verwissenschaftlichung in Raphael's essay. Raphael discusses in broad terms numerous important historical cases of the application of disciplinary expertise and stresses its uses as a social technology in addressing problems created by the economy and the welfare state, chiefly in Germany but also in France, Britain, and the United States. Reading Raphael in order to clarify the meaning of Verwissenschaftlichung is a dead end.

Does Tribe's minimalist explication of his analytical machinery actually damage his project? Perhaps not. In a public address in Munich on November 7, 1917, no less a figure than Max Weber presented an informal account of Disziplinierung and Verwissenschaftlichung as employed in CES, although he did not use these terms. This was “Science as a Vocation,” which became an instant classic in the German literature and, following its translation into English after World War II, a basis of subsequent work in the sociology of science (Weber 1946). Tribe's passing remark that Weber's “social and economic analysis suffuses” his book is not a ritualistic gesture (xi). The six elements that constitute his tacit analysis of Disziplinierung reproduce down to fine points of detail Weber's account of “modern science” in the first part of the lecture (Weber 1946: 129–34). As a political economist, he proposed to follow a “pedantic” practice of his discipline in beginning by considering “external conditions”—“the conditions of science as a vocation in the material sense of the term” (Weber 1946: 129). Tribe's account of Disziplinierung follows the main lines of Weber's discussion of these conditions. Once these external conditions are satisfied, the progress of science is locked into the logic of Disziplinierung. In one of his famously arresting metaphors, Weber claimed that science is “chained to the course of progress,” an implacable process of intellectual “rationalization” that systematically conceptualizes the world on the basis of the methods of science (Weber 1946: 137–39). Although Tribe resists the Weberian language of rationalization because of its teleological overtones, Verwissenschaftlichung is a rendition of Weber's idea of the “inner” or immanent intellectualization of the world that modern science produces. Both are a result of the Disziplinierung of science, in which a progressive specialization of expertise produces a science that neither requires nor acknowledges any validation beyond its own methods.²

What Is “Marshallianism”?

Tribe dismisses the idea of understanding Marshallianism as the theoretical program of Marshall's Principles—the book that, in Cambridge-insider historiography, laid the foundations of a “Cambridge tradition.” Instead, he treats it as a pedagogical scheme in which the master's purpose was to orient students to his conception of how economics should be studied and practiced—in essence, his view of the imperatives imposed on the professional socialization of the apprentice economist by a vocation in commerce, manufacture, or public administration (152, 171). Marshallian pedagogy would produce graduates with a socio-professional identity grounded in a distinctive conception of what it means to be an economist. Following this strategy, Tribe reviews the records of Pigou and Sidney Chapman as Marshall's students: what they learned from him and what they made of it. Although he insists that it is unnecessary to “‘intuit’ Marshall's ‘intentions’” or to determine “‘what he meant to do’” (76n3), this is what readers find in his exposition of Marshall's objectives as set out in his lectures on political economy and the inaugural lecture of 1885 (95–100). Here Tribe is engaged in a standard exercise in the history of ideas, a method in which he claims to see little value. It rests on “epistemologies” in which the historian supplies a context for one text by reading yet another.

How could it be otherwise? A pedagogy presupposes pedagogical ideas and ideals. A Marshallian syllabus could not be understood or written without some plan indicating what it is expected to achieve. Pedagogy and analysis are not independently identifiable entities. If a specification of what qualifies as sound economic analysis is a logical condition for the possibility of pedagogy, it is mistaken to suppose that material and cognitive cultures are dichotomies or that the material is a noncognitive sphere of validation independent of a cognitive sphere of reasoning.

The Oxford Question

In his various counterfactual claims regarding what would or would not have happened had Marshall not left Oxford for Cambridge, exactly what position is Tribe taking? Is it, as he sometimes claims, an impossibility thesis: the takeoff to economic science could not have begun at Oxford? Because of its governance and pedagogical structures, faculty organization, and intellectual traditions, “Oxford did not—could not—provide a platform upon which a new discipline of economics took shape” (193). Is it a much more modest claim: had Marshall remained at Oxford, he would have been unable to achieve his subsequent reputation (369)? Is it a probabilistic thesis: had Marshall become the Drummond Professor at Oxford, his plans “might have taken a rather different direction,” in which case “the early history of the discipline of economics would not have turned out the way it did” (177)? Is it a replication thesis: the conditions in Cambridge that “led to the creation in 1903 of the three-year undergraduate degree could not have been replicated in Oxford” (4)? The probabilistic thesis is a statement about what might, and thus might not, have happened. It entails no revisionist consequences for the history of economics. The reputational thesis is too vague to be of use for analytical purposes. The replication thesis is a tautology. Although the impossibility thesis is of considerable interest, it has little support in CES and is compromised by evidence, provided by Tribe himself, that he may subscribe to a weaker variant. Moreover, his defense of the impossibility thesis rests on an implicit ceteris paribus premise: all conditions prevailing at Oxford during Marshall's Cambridge professorship would have remained what they were with the single exception of Marshall, who would have become professor at Oxford instead of at Cambridge. On Tribe's own reasoning, all things would not have remained the same. Consider his conception of Marshall's immense energy, drive, irascible nature, and determination to override or destroy all obstacles in his path. In view of his allegedly difficult character, claims concerning the entrenched status of the Oxford Politics, Philosophy, and Economics degree (PPE, an Oxford version of the Cambridge Moral Sciences Tripos) as well as the traditional curricular weakness of mathematics and the strength of classics at Oxford pale in significance. At Cambridge, opponents of Marshall's plan relented not primarily because the constellation and interplay of institutional variables worked in his favor: he had become an intolerable irritant, “whose cantankerousness prompted his colleagues to give him what he wanted so that he might leave them alone” (101). If Marshall could move Moral Sciences colleagues at Cambridge to surrender on the strength of brutishly inconsiderate conduct, why could he not have achieved comparable results with PPE colleagues at Oxford? Tribe's reasons for claiming that Marshall could not have succeeded at Oxford also seem to be reasons why he should have failed at Cambridge, which of course he did not. Or did he? Exactly what is ruled out as impossible at Oxford? A three-year economics degree closely approximating the Cambridge Tripos as Marshall conceived it but, as Tribe shows, was unable to fully implement? An economics degree with elements of the Oxford PPE, which on Tribe's own account would not have differed substantially from the Tripos that was actually enacted between 1905 and 1914? What changes, in Tribe's view, would have been minimally necessary to initiate economic science at Oxford? In CES, these questions are not considered.

The View from the Cam, 1920–38

Exactly why was Cambridge the first university to develop economic science? Tribe's readers are left with ambiguous answers. Was Cambridge the only economics faculty during Marshall's professorship to succeed in meeting Tribe's criteria for Disziplinierung? He makes the case that this was Marshall's objective but does not provide evidence that Cambridge satisfied them. Or were there, as Tribe also suggests, no other contenders, leaving the field to Cambridge by default? “‘Cambridge prevailed’ in the establishment of a new form of economics because there never was a viable programmatic alternative” (197–98).

Although Tribe leaves readers in suspense concerning the explanation of the rise of Cambridge to first place, he is unequivocal regarding its transient dominance and the reasons why this seems to have been inescapable. His logic is simple. (1) To sustain a leadership position in economic science, a faculty required a structure making it possible to build to scale. (2) Building to scale required a pedagogy that relied heavily on lectures in which large numbers of students could be taught efficiently, creating demand for additional and more specialized faculty and thus a larger supply of teachers to attract more students. (3) At Cambridge, colleges were the main sites of teaching, which took place in supervisions (elsewhere generally called tutorials), not lectures. (4) Because Cambridge was locked into a collegial tutorial system—quasi-personal, self-limiting, and inefficient—its dominance would inevitably be short-lived, to be superseded by an economics faculty in which lecturing in a uniform curriculum designed to systematize professional training was the chief pedagogical mode.

Sic transit gloria mundi. “The Cambridge moment” is not an epochal metaphor comparable to the title of J. G. A. Pocock's monumental treatise The Machiavellian Moment (1975). In Tribe's master narrative, Cambridge seemed doomed to fall behind and be surpassed, contrary to his frequent strictures against institutional determinism and teleological thinking. The causes lay within, produced by flaws endemic to the Cambridge pedagogical scheme. Its seeds were planted long before Marshall's arrival, ensuring that even from its inception the Tripos could not be sustained as the market leader of a progressive scientific discipline. At this point, we probe the two main historical premises of his argument: college supervisions as the main delivery system of Cambridge teaching and the pedagogical insignificance of lectures.

At Cambridge, supervisions were recognized as a seriously inadequate means of preparing students for the Economics Tripos. In colleges that offered few fellowships in economics or none at all, students met their needs by approaching either fellows of other colleges or supervisors who had no college fellowships. The economic historian C. R. Fay, a fellow of King's, “blushed to own” that for some years he had supervised students in nine colleges (Cambridge University Reporter, 3/31/1920, 768). Joan Robinson conducted supervisions for more than thirty years even though no college had granted her a fellowship—she was finally elected a fellow of Newnham in 1962. In Austin Robinson's assessment, Fay was “completely innocent of any real understanding of Marshallian economics” (Robinson 1992: 208). Joan Robinson knew Marshall, Pigou, and Keynes but very little economic history. Keynes, an expert in money, banking, and finance, showed little interest in what came to be known as microeconomics. Gerald Shove, a student of the theoretical intricacies of value and distribution, had no expertise in macroeconomic issues. In sum, no supervisor was competent to cover all the subjects that students needed to learn in order to succeed in the Tripos examinations.

Supervisors could of course recommend readings independent of supervisory assignments. However, independent reading of recommended sources did not guarantee success. Students were warned that Faculty Board recommendations were only “intended for general guidance.” They were cautioned that examiners were “in no way bound by these lists” (Cambridge University Reporter, 6/22/1920, 1190; see also 6/7/1927, 1222). In the 1930s, Pigou, Dennis Robertson, Fay, Shove, Austin Robinson, Kahn, and at times Keynes were examiners. Thus prudence suggested that students become familiar with their thinking on economics. In this regard, lecture attendance was a more secure path than independent readings, and for reasons not difficult to fathom. It was standard practice for Cambridge economists to lecture from works in progress or recently published books. Pigou offered courses on public finance for years before publishing his classic on the subject, A Study in Public Finance. In the 1920s, Keynes lectured on issues linked to the Tract on Monetary Reform and the Treatise on Money, and in the 1930s on The General Theory in the making. For a time, Kahn lectured on the economics of the short period, the subject of his unpublished fellowship thesis. In such cases, it would have made little sense for students to seek advice from supervisors on the recent thinking of Tripos examiners; the works in question were not yet published, remained unpublished, or had been published too recently to be understood by Tripos standards. The legendary Cambridge Circus was formed in late 1930 because, as supervisors, the Robinsons and Kahn needed to understand Keynes's Treatise on Money, which had just been published and would be prominent in their tutorials.

The 1926–38 minutes of Faculty Board meetings demonstrate the importance that the faculty ascribed to lectures. From inception in 1903 through 1938, they took great care in arranging courses of lectures for Part I and Part II Tripos students. Before 1926, lecture lists were decided in faculty conferences, where lecturers recommended lists of books and accepted, rejected, or otherwise modified syllabi proposed by current and aspiring lecturers. After 1926, these functions were performed by the Lecture List Committee, which operated harmoniously into the early 1930s. By the mid-1930s, as the Keynesian heterodoxy gained ground and Keynesian partisans were appointed to lectureships, decisions on lectures and lecturers became contentious. The intramural controversies over the lectures of Joan Robinson—Keynes's most aggressive and doctrinaire advocate—show what was at stake. If Cambridge lectures were pedagogically insignificant, why was there a furor over her treatment of Robertson's traditional lectures on money? Why did her syllabi for a two-term course on applied monetary theory, proposed for 1934–35 and intended for Part II students, engender so much dissension? Why was Robertson emotionally distraught? Why was Fay moved to send a letter to the Robinsons and another to Keynes, Pigou, and Shove, expressing his fears that Keynesian monetary theory might achieve “a sort of theoretical suzerainty” over the curriculum? Why was Keynes so perplexed by the contretemps that he wrote his wife Lydia about it (see Aslanbeigui and Oakes 2009: 275–76)?

Nor do the minutes of board meetings provide evidence of doubt on the part of the faculty regarding their ability to scale up their lectures to compete with other programs, either in the United Kingdom or elsewhere. Moreover, they did not lack grounds for confidence in this respect. By the mid-1920s, they could boast of sufficient financial independence and stability to maintain their competitive position and progress.

In early 1920, university resources devoted to instruction in economics were remarkably similar to those in place before the Great War. Pigou held the only professorship. Walter Layton had been replaced by Hubert Henderson. Frederick Lavington would soon become the Girdlers' lecturer, replacing Keynes, who had reduced his teaching commitments after the war. The remaining lecturers were supported by college fellowships and teaching appointments. For a number of reasons, this arrangement failed to reflect postwar realities. Although there was a substantial uptick in the number of new students entering economics, increasing the need for lecturers, the Special Board (as the Faculty Board was called before 1926) argued that competition for “lecturers of a high degree of competence” had intensified owing to the attraction of government service and a mushrooming of “Schools of Economics in the principal Universities and throughout the Empire.” Moreover, the Cambridge method of remunerating instructors not on the university payroll was “highly unsatisfactory.” Many drew income from lecture fees; since lecture subscriptions were notoriously unpredictable, the Special Board could make only conservative offers, unattractive relative to what prospective lecturers could earn elsewhere. Reliance on lecture fees created a further difficulty: since most students subscribed to “general elementary courses,” a lecturer teaching advanced courses stood to lose an annual sum of £200–£300. This incentive structure was an impediment to instruction in Part II of the Tripos, which produced the future economists. In sum, the budget of the Special Board was precarious and its compensation scheme inefficient and inequitable. Superior instructors were available but not without much more generous support from the university. Since the war had left university finances in shambles, measures to reform Cambridge economics education were imperative (Report of the Special Board included in the Minutes of the General Board of Studies, 2/6/1920).

The Special Board proposed a solution to this conundrum: a system of “inclusive terminal fees”—covering attendance at lectures, marking papers, and use of the departmental library—to be charged to all students who planned to sit for various economics exams. The board would create a self-administered departmental fund as the single repository of revenues from all sources generated for economics pedagogy. Fees, stipends, library expenditures, and any other disbursement “for the promotion of the study and teaching of Economics in the University” would be determined at the discretion of the board (Report of the Special Board included in the Minutes of the General Board of Studies, 2/6/1920).

The proposal, submitted to the General Board, was sent to the University Senate for discussion on March 11, 1920. Making the case for the Special Board that there was an urgent demand for economics education, Keynes argued that they could not afford to postpone recruiting lecturers until the snail-like machinery of Cambridge had generated new positions. They were in danger of losing promising young economists who were “almost sure to obtain” attractive positions elsewhere. The real problem, he said, was to keep the economics faculty “together at all.” The proposal was “a careful attempt to meet problems in a subject for which the University had not been able to make much provision, and which was now attracting large bodies of students” (Cambridge University Reporter, 3/31/1920, 770–71).

The Special Board had hoped for a swift decision, fearing bureaucratic inertia and the “ridiculous course of referring its request from one body to another” (Cambridge University Reporter, 3/31/1920, 768). As months passed and the senate temporized, deferred action, and called for revisions, that was indeed the immediate fate of the proposal. It was eventually approved and memorialized by “Grace of the Senate” in December 1922. A subcommittee of the Special Board—Pigou, Keynes, John Clapham, and Henderson—prepared the “Scheme for the Formation of an Economics Departmental Fund” in 1923. In 1924, a third lectureship in economics was established and filled by Robertson (Cambridge University Reporter, 5/23/1923, 1050–51; Minutes of the Special Board, 1923–24). He was followed by Maurice Dobb (1925), Shove (1926), and Austin Robinson (1929). By 1930, the “Cambridge School of Economics” had assembled a cast of theorists, lecturing in a department that they understood—on the basis of evidence at the time—as scientifically progressive and academically competitive.

The End of Teleology?

University financing and mobilization of financial support were essential elements of the material context for the creation of economic science. As the Cambridge economists of the 1920s understood, innovation in financing was crucial to the future of institutional Marshallianism and its capacity to compete in the postwar academic economy. Why is CES silent on these matters? One answer lies close to hand. Tribe's account of Cambridge in the 1920s—stagnation followed by rapid decline and fall from supremacy—is not based on the perspective of the Special Board or the material context of their time as they understood it. It is built on his conception of a fleeting Cambridge moment and its logical function in his argument for the main thesis of the book. On that thesis, the genesis of economic science is a story about the construction of a discipline in which validity is held to follow solely from the analytical tools produced by the discipline itself. In its most extreme version, it could be said that economic truth is a creation ex nihilo, and the economists who create it are epistemic gods. This thesis poses a worrisome problem for Tribe, the antiteleologist whose objective is to explore the formation of economics in the institutional setting of its time. From Marshall to Austin Robinson, every Cambridge economist between 1903 and 1930 rejected the conception of economics entailed by the Verwissenschaftlichung thesis. No one made the Cambridge consensus of the 1920s on the historicism and pragmatism of economic analysis clearer than Pigou, Marshall's successor, whose lectures on principles of economics were the basis of Tripos pedagogy in the 1920s. The validity of an analysis is not decided by the logic of economic science. It is tied to current economic and political conditions and limited by changes in their complexion: economic generalizations holding true today may prove to be false tomorrow, and it is impossible for economists, who are embedded in history, to make scientifically reliable estimates of their scope and the limits of their validity.

What are the consequences of this awkward fact for Tribe's project? There seem to be two possibilities. If Pigou, Keynes, and their colleagues in the 1920s regarded the immanent validation of economic analysis as a preposterous idea, then there was no Cambridge moment as Tribe understands it. In that case, the argument of CES falls apart. Or suppose Tribe holds that, regardless of how interwar Cambridge economists understood their work, they were actually engaged in economic science as a self-legitimating discipline—albeit in an unwitting and confused fashion. On this view, a retrospective interpretation of the trajectory of economic science and its history illuminates the achievements of Marshall and his students in a way that they did not illuminate them, and perhaps could not have illuminated them: as harbingers of a future self-validating science. In that case, Tribe is no longer the antiteleological scourge of rational reconstructionism. Joining the camp of his adversaries, he leaves the conception of CES in shambles.

Regardless of how this dilemma is resolved, the observations Keynes made to Kahn in February 1938 suggest that in Tribe's thesis of Cambridge decline, he glimpses a sound and fateful idea—but in the wrong decade and for the wrong reasons. That, however, is another story and territory for an as yet unwritten essay.

The authors are grateful to Jacky Cox, Keeper of University Archives, and Patricia McGuire, King's College Archivist, the University of Cambridge.

Notes

References