Kahn as a Cambridge Economist

In an earlier work we characterized the Cambridge economists in the interwar years as a group whose

identity stemmed from motivations, values, life-styles and work-styles, leaving room for reciprocal respect, overriding many contrasts, and keeping the sense of belonging alive; .. .the points of theoretical division, precisely because they generated discussion, did not break the group up but served to form a connective tissue; .precisely because there was no common corpus of accepted ideas to defend, the characteristic feature seems rather to have been elitism—a system of cooption based on characteristics that were neither ideology nor exactly academic performance or success, but rather the features of a moral and intellectual aristocracy (Marcuzzo et al. 2008: 583).

Kahn fits this description perfectly and, although not a prolific writer,^[1] he had an extraordinary influence. This can be seen in the two most important books produced by Cambridge economists in the 1930s, Keynes’s General Theory and Robinson’s Economics of Imperfect Competition.

Kahn contributed more significantly than anyone else in the circle around Keynes to the Keynesian revolution. The relations between Keynes and Kahn were strong, continuous, and fertile, with an apparently paradoxical inversion of roles: it was the pupil who intervened to correct, tidy up, and sound out the master’s rationale. There are aspects independently worked on by Kahn that Keynes subsequently incorporated, adapting them to his aims and forma mentis, which eventually became part of The General Theory, readjusting the framework upon which his Treatise on Money had rested. The major points where Kahn’s influence can be better appreciated are short-period analysis and the application of aggregate demand and supply to determine price levels and equilibrium quantities. Within this framework, the multiplier principle and the supply schedule for output as a whole were tools that proved particularly productive in building the new theory.

The other intellectual and indeed strong personal relationship which was pivotal in Kahn’s life was with Robinson. There is hardly a theoretical work by Kahn in which mention is not made, with approval, of the ideas of Robinson, showing how the work of one would be carefully read and commented upon by the other, even when their main fields of research and approaches diverged, as they soon did after their joint work on imperfect competition and on Pigouvian themes in the early 1930s. Their collaboration started during the writing of Robinson’s Economics of Imperfect Competition. The collaboration probably proved congenial from the outset because they both shared a method of analysis based on meticulous classification of all the possible combinations of two or more elements, the reasoning often going: if X can be A or B and Y can be C or D, let us examine all four combinations AC, AD, BC, and BD. Behind this method of reasoning there were, however, probably two different needs. Robinson had no other analytic tools at her disposal. She knew absolutely nothing of calculus, and headway could only be made in a rigorous manner by breaking the problem down into simple cases which might be examined one by one. Kahn had been educated as a physicist and this method satisfied his need for order, his love for taxonomies, as well as paving the way to pinpointing real cases corresponding to the theoretical cases examined. However, since Kahn had mathematical demonstration at his command, we cannot tell whether his choice in suggesting to Robinson that she use geometry instead of calculus for the proofs in the book was dictated by a personal preference for the graphically representable or the decision to use only such tools (high school geometry, trigonometry) as were accessible to Robinson and the average economist (see Rosselli 2005). After the Second World War, their interests somewhat diverged since Kahn did not take part in the capital controversy of the 1960s and 1970s and was more involved in active economic policy, but many intellectual ties continued to unite them: the fight for Keynesian ideas and against laissez-faire policies, both in the public arena and in Cambridge academic life.

Kahn’s relations with both Keynes and Robinson, although obviously different in kind, epitomize the kind of intellectual collaboration that was typical of Cambridge: a sharing of time and space, which ‘also entailed a sharing of knowledge and the habit of exchanging rather than possessing ideas’ (Marcuzzo and Rosselli 2005: 10).

Finally, mention should be made of the influence on Kahn of Gerald Shove, since it is often neglected. Shove, who became Lecturer in Economics in 1923 and only in 1926 was made Fellow of King’s College, published very little; he worked for years on a book which was never finished and all his papers were destroyed after his death in accordance with his will. However, we know that he was an excellent teacher and all his students preserved fond memories of and admiration for him. Kahn was no exception. He learnt his Marshallian economics from Shove, attending his lectures, and in his Fellowship dissertation he acknowledges his debt to Shove. Respect and affection lasted over the years; it was Kahn who wrote Shove’s obituary for the King’s College Annual Report in 1947 and, in his article on Shove for the Palgrave Dictionary, he called him a ‘dauntless thinker’. The apparatus of Marshallian partial equilibrium, on which Kahn’s reasoning rested all his life, was part of Shove’s enduring legacy to him.

• [1] Kahn published only one volume of collected essays, Kahn (1972).