“This book is the story of how a student with a humanities background came to economics through an interdisciplinary education in the social sciences, recognizing as an undergraduate that mathematics could be the key to unlocking the secrets of the subject” (p. 630). What makes that story worth telling is that this particular “student” soon came to occupy a position in the intellectual history of our discipline comparable with that of Adam Smith, Léon Walras, and John Maynard Keynes: as one of a tiny handful who have decisively enlarged the scope and nature of economic inquiry. For, according to Professor Backhouse, Paul Samuelson became the “Founder of Modern Economics.” Because that claim rests to a considerable extent upon two books, Foundations of Economic Analysis (1947) and Economics: An Introductory Analysis (1948), and because Samuelson was only thirty-three in 1948 and at an early stage of his career at MIT, his education, upbringing, and development are of more than ordinary biographical interest.

His young life in Indiana, his years at the University of Chicago, his membership in the Society of Fellows at Harvard, and his wartime work in Washington show the subject “Becoming Samuelson”—a process that was complete by 1948. Volume I of this biography therefore ends at that date. Almost to the end of his remaining sixty-one years, Samuelson continued to explore, develop, and apply the “Modern Economics” he had “founded”; and that, we may suppose, will be reported in Volume II.

In chapter 1 Roger Backhouse describes Paul’s childhood: in Gary, Indiana, where his immigrant parents settled, and on a farm belonging to friends near Valparaiso about fifteen miles away, to which he was sent for considerable periods until his parents moved to Chicago. There he attended High Park School until entering the University of Chicago in 1932. The remainder of the book falls naturally into three periods: the formative years in Chicago, 1932–1935 (chapters 2–5); Part II, “The Harvard Years, 1935–1940” (chapters 6–15); and Part III, “MIT, War, Foundations, and the Textbook, 1940–1948” (chapters 16–29).

On 2 January 1932 the young Samuelson was “born again”: at an early morning lecture on Robert Malthus’s population theory (p. 23). Though he had been chiefly interested in literature during his high school years, he understood enough mathematics to formulate the process, and from that moment he was hooked on economic theorizing. Though fruitfully engaged with the compulsory Humanities component of the Chicago curriculum, he took increasing interest in economics, studied in connexion with the other social sciences. His introductory course was taught by Aaron Director and Lloyd Mints, by whom he was introduced to work of Sumner Slichter, Gustav Cassel, Richard Ely, and Allyn Young. His studies in the natural sciences introduced him to the heuristic value of mathematics in formulating problems, and in chemistry he first encountered the Le Chatelier principle later to be important in Foundations. Subsequent specialization in the social sciences, in which Chicago was then pre-eminent, brought Samuelson into contact with Frank Knight and Jacob Viner, each of whom, Backhouse considers, were of deep and lasting influence on his thinking. Perhaps as important was the intellectual society of his fellow students, which included Jacob Mosak, Martin Bronfenbrenner, George Stigler, W. Allen Wallis, and Milton Friedman, who married Aaron Director’s sister, Rose. In his final year he took five mathematics courses and a further course in differential equations in the summer, leaving Chicago “having taken more mathematics courses than any other economics student” (p. 72). His exceptional ability in mathematics had gained him admission into Viner’s graduate course in economic theory, where on more than one occasion he was able to correct errors in Viner’s diagrams (p. 87).

Perhaps the most important period in the process of “Becoming Samuelson” was 1935 to 1940, during which Samuelson began graduate studies in economics at Harvard, was elected to the Society of Fellows in 1937, met Marion Crawford, whom he married in 1938, and completed the doctoral thesis in 1940 that became Foundations. It was at Harvard where his intellectual formation was determined: for though he had been introduced to a species of “operationalism” at Chicago by Henry Schultz, it was the Harvard physicist Percy Bridgman whose exposition most influenced Samuelson. And many others—including Joseph Schumpeter (his mentor and thesis examiner), Lawrence Henderson, Alfred N. Whitehead, Alan Sweezy—were part of a vigorous methodological conversation owing much to the Vienna Circle of the 1920s. It gradually became clear to Samuelson that economic theorizing was futile unless it could formulate operationally meaningful theorems: “hypotheses about empirical data which could conceivably be refuted” (p. 275). For comparative statics this implied not only that general equilibrium must exist and be unique, but also that it be stable: for only then could we predict the effects of parametric change. By 1940 Samuelson had published several important mathematical articles; but so had many of his contemporaries. Moreover, economists had been formulating sophisticated mathematical analyses at least since Johann Heinrich von Thünen, Antoine Cournot, William Jevons, and Walras. What made Samuelson’s achievement unique and revolutionary was his use of mathematics to lay bare the methodological “foundations of economic analysis.”

Backhouse’s Volume I stands or falls by his exposition of this centrally important episode in his subject’s career. Though his treatment of its many elements is interspersed with much other biographical material over 209 pages (pp. 83–292), we are told all we need to know in rich and informative detail: from Schumpeter’s brilliant, off-the-cuff Lakatosian insight (“you never . . . kill a theory by a fact; you kill a theory by a better theory,” p. 144) to the illuminating interpretation of Le Chatelier’s principle as applicable not only in physical chemistry but also both in economics (p. 282) and in ecology (p. 351).

Second only in importance during Samuelson’s formative Harvard years was the arrival in 1937 of Alvin Hansen, who “for around a decade” became “his most important mentor” (p. 236). Backhouse deals carefully and judiciously with the mythopœia in Samuelson’s account of his own, and of Hansen’s “conversion” to Keynesian ideas (pp. 234–237). Yet though many senior Harvard economists—including Edward Chamberlin, Seymour Harris, Gottfried Harberler, Schumpeter, and Wassily Leontief—were unimpressed by or even hostile to the General Theory and its policy implications, the younger generation was already infected by the “tropical disease.” The Canadians Robert Bryce and Lorie Tarshis, who had studied under Keynes at Cambridge, Paul Sweezy, John Galbraith, the brothers Walter and William Salant, and James Tobin were all inclined to the “New Economics.” Hansen himself was a business cycle theorist, and this was Samuelson’s own initial approach to macroeconomics. According to Backhouse, Samuelson became “Hansen’s Disciple” (ch. 13) and like his mentor only gradually came to digest and appropriate the Keynesian message over the next decade. Soon after his move to MIT in 1940, it was his first graduate student, Lawrence Klein, who finally convinced him to accept and embrace the “Keynesian Revolution” (ch. 24).

Part III of this volume begins with the move to MIT, and then tells of Samuelson’s wartime work in Washington and his technical research on fire control, and of his increasing commitment to postwar economic policy in which the influence of Hansen remained important. It also reports the conversion of the thesis into Foundations and the reception of that work (ch. 22); and the distillation of Samuelson’s wartime experience as a “general economist,” together with his “Keynesian” employment theory, into his famous textbook (chs. 25–27). Non-American readers will be astonished to read of the pious horror felt by powerful business interests at Samuelson’s mildly interventionist policy recommendations in that book, and by the power they believed they had over MIT to censor this publication by one of its faculty (ch. 26).

The book ends with a chapter (29) on “The Young Samuelson,” which beautifully summarizes the previous 613 pages. The reader who wants a quick fix on this important book about that most important economist should start there.

When one goes back to read the whole book carefully, which one certainly ought to do, various conceptual and historiographic questions may occur to the professionally trained reader. Here, by way of example, are three.

What are we to understand by “modern economics”? Did it begin with Antoine de Montchrestien; or with Pierre Le Pesant, sieur de Boisguilbert; or with Adam Smith; or with Jevons? There is a demonstrable intellectual continuity in “economic analysis” at least from Boisguilbert (or at any rate François Quesnay) to the present, as Samuelson (e.g., 1978, p. 598) himself clearly recognized: “within every classical economist there is to be discerned a modern economist trying to be born.” Economic phenomena in human societies are to be explained as the unintended consequences of the self-regarding acts of rational individuals. The so-called Marginal Revolution is a myth of second-rate textbooks; the “Keynesian Revolution” is more defensible, but that did not change economics: it enlarged it. Neither in his Introduction (pp. xix–xxi) nor in his final chapter does Backhouse tell us clearly what he means by “modern” in this context; though he appears to regard the greatly increased use of mathematics and econometrics, the assimilation of the “New Economics” (i.e., Keynesian macro theory), and “a move from pluralism to neoclassical economics” (p. 615n.) as characteristics. But the tautology “modern economics” is what Samuelson “founded” will not work in these cases, for “Samuelson was not the only creator of the new ways of doing economics” (p. 628). I wish to suggest that what Samuelson did uniquely “found” was methodological: the use of mathematics—given the assumption of human rationality—in order to design testable models. Now the tautology works. And it’s all in Backhouse!

Secondly, what about “operationalism”? Backhouse associates Samuelson’s adoption of this idea with Percy Bridgman, a Harvard physicist well known in the Society of Fellows: “questions were meaningless if it was not possible to find operations by which the answers could be obtained” (p. 199). Bridgman’s methods had been adopted by the logical positivists at Harvard and a connexion with the Vienna Circle is suggested (pp. 200–201). Logical positivists held that a proposition is meaningful only if its truth value is empirically verifiable. Yet Karl Popper showed that verification in this sense is impossible. We can falsify hypotheses only empirically. Though Samuelson was sometimes vague about “operationalism” (e.g., p. 216), he defined operationally meaningful theorems in his thesis as “hypotheses about empirical data that could conceivably be refuted” (p. 275). This is a rejection of the Vienna Circle’s verification principle, and Backhouse indeed surmises that Samuelson’s methodology “sounds more like Popper than Bridgman” (p. 276). Popper was never a member of the Vienna Circle and rejected logical positivism. There is, however, no evidence that Samuelson had encountered the work of Popper at this time (p. 201n.). What then? “It is hard not to conclude,” Backhouse finally tells us, that Samuelson “had no deep interest in the philosophy of science” (p. 450); “he sampled it and moved on” (p. 451). Readers must make up their own minds about this. Samuelson had immense intellectual energy and a devouring thirst for knowledge of every kind. “Meaningful theorems” were central to his economic analysis. Did he inadvertently reinvent (part of) Popper’s wheel?

Thirdly, of particular interest to readers of this Journal, what of the history of economic thought (HET), of which Roger Backhouse himself is a distinguished scholar? Between 1957 and 2009, the last year of his life, Samuelson published no fewer than seventy-six articles in HET, many in leading journals and some of crucial importance. Even had he done nothing else in his working hours, Samuelson would be a very important authority in our sub-discipline. However, the terminus ad quem of this volume is 1948. Can we perhaps regard Foundations (1947) as an essay in HET? That work refers to nearly forty of his more famous forerunners over the previous two centuries, ranging from Enrico Barone, Frédéric Bastiat, Jeremy Bentham, Eugen von Böhm-Bawerk, Ladislaus Bortkiewicz . . . to Adam Smith, Thünen, Veblen, Viner, Walras, Knut Wicksell, and Allyn Young; and including such relatively unexpected authors as Friedrich Engels, William Paley, and Henry Sidgwick. The only major figure to be omitted is Karl Marx, to whom Samuelson devoted much attention later. He illustrated a purely mathematical conception—“one-sided stability-instability”—with Malthus’s population theory; thereby formulating a Malthusian production function, the germ of his famous “Canonical Classical Model” (Medema and Waterman Reference Medema and Waterman2010). In my opinion it is not too fanciful to think of Foundations as an attempt to identify the analytical core—the Popperian “unity of method and logic”—of all that economists had been doing at least since Adam Smith. At his Nobel Banquet Samuelson listed as a condition of academic success in economics “an important one from a scholarly point of view, you must read the works of the great masters.” Few other economists have “read the works of the great masters” with the diligence and penetration of Paul Samuelson, and there are clear signs of this in his earliest work.

To say that this volume is worthy of its subject’s astonishingly precocious achievements —which it is—is high praise indeed. But it is a pity that it should be slightly marred by many misprints (including wrong labelling of the vertical axis in the famous “Keynesian cross” diagram, p. 366); and by a somewhat unhelpful Index, in which many important concepts (e.g., “imperfect competition,” “liquidity preferences,” “production function”) do not appear.