1There is little doubt that a good case can be made to consider Leontief and Sraffa as the founders of linear production theory. Leontief’s work constituted the basis for input-output economics, which is widely used in applied economic research, while Sraffa’s writings led to the development of neo-Ricardian economics, of which the contributions are mainly theoretical. At the beginning of the 20^th century, however, and years before Leontief and Sraffa started publishing, several economists – for instance Georg von Charasoff (1910) or Maurice Potron (1911) – independently conceived models of the input-output type and studied their formal properties. The historical sources of these approaches are more ancient and Sraffa, for instance, was directly inspired by the Classical tradition.

2In recent years new studies have been published on these early formulations of linear models. In order to synthesize these studies and to compare the different approaches, EconomiX (University of Paris Ouest), with the support of the Department of Economics of the University of Antwerp and of the Cahiers d’Économie Politique, organized a two-day colloquium on ‘The Pioneers of Linear Models of Production’ in January 2013. The initiative to devote an issue of the Cahiers d’Économie Politique to the same theme was taken some time after the colloquium. Many of the articles in this issue are revised versions of the papers presented at the colloquium; a few are new contributions. All submissions have gone through the usual reviewing process of the journal.

3The first two articles take us back to the second half of the 18^th century and to the path-breaking contributions of the Physiocrats: the Physiocratic school may be considered as the main historical source of input-output analysis because it was the first to develop a consistent view of production as a circular process. Richard van den Berg and Albert Steenge revisit the works of François Quesnay and of Achilles Nicolas Isnard, and argue that Quesnay and Isnard can be considered as forerunners of linear approaches to macroeconomic modelling. While Quesnay’s Tableaux are mainly pictorial representations of the economy, Isnard, who lived a generation after Quesnay and was an engineer with a good training in mathematics, developed formal modelling in his Systèmes and wrote down sets of simultaneous equations. The authors draw attention to his little known but surprisingly modern conceptions. Pierre Le Masne proceeds to a closer and more direct comparison with modern formalisations by reconsidering the similarities and differences between Quesnay’s Tableau Œconomique and Leontief’s input-output tables. The transposition of the accounts of Quesnay’s Philosophie rurale in terms of modern accounting, with two variants, allows us to better understand the technical correspondences between these two constructions, and also to identify conceptual differences, Quesnay’s approach being more ambitious than input-output analysis as we know it.

4We then jump over the whole 19^th century and move directly to the beginning of the 20^th century. Georg von Charasoff is an economist whose main work, published in 1910, is devoted to a critical analysis of Marx’s price theory and the question of the ‘transformation’. That work was rediscovered more than seventy years after its publication, and Charasoff has since been acknowledged as a forerunner of Leontief’s and Sraffa’s analyses. In particular, his notion of “Urkapital” is formally close to that of Sraffa’s “standard basket”. Charasoff’s contribution makes no use of abstract mathematics, but it is suspected that Charasoff ‘rubbed out’ the equations when he published his work (in our times, ironically, the presence of equations would be considered as a proof of seriousness …). Kenji Mori’s draws a parallel between Charasoff and the development of matrix theory at the beginning of the 20^th century and shows that Charasoff anticipated results of Richard von Mises (the brother of the economist Ludwig) and Hilda Pollaczek–Geiringer.

5Maurice Potron, a French Jesuit, may be considered as the hero of this special issue, with one paper devoted to his life, another to his economic model, and an annotated bibliography. There is indeed a special link between Potron and the Cahiers d’Économie Politique: during Potron’s life, the very existence of his economic model was only known by a few Polytechnicians and it had been totally forgotten for more than fifty years. Émeric Lendjel rediscovered it in 2000, published a letter from Potron to Gibrat in the Cahiers and commented it: the letter provides evidence that, thirty years before any other economist, Potron made use of the Perron-Frobenius theorem in order to prove the existence of ‘satisfactory regimes’. It is shown here that Potron also stated explicitly the first duality theorem and invented the so-called ‘Hawkins-Simon’ criterion. Potron’s biography, by Christian Bidard and Guido Erreygers, shows his lack of academic knowledge in economics and the importance of religious sources in his approach. This explains his failure to weave a network of relationships with the economists of his time. However, very recently, Olav Bjerkholt discovered a letter from Potron in the Frisch archives at the University of Oslo, in which Potron explains (or at least tries to explain …) the difficulty of finding satisfactory regimes. Erreygers and Bidard translate that letter, and seize the opportunity to analyse the structure of Potron’s model in more detail. Potron was also a mathematician and Wilfried Parys’s annotated bibliography will become an essential working tool for further researches. It gives a fascinating overview of the whole of his scientific output: Potron only published in economics during two periods, from 1911 to 1914, then from 1935 to his death in 1942.

6One cannot imagine an issue on input-output analysis without a study on Leontief. Two papers go deeper into Leontief’s work. Louis de Mesnard’s paper is mainly analytical. Leontief’s stroke of genius, it is argued, was to make use of monetary data, which are easy to collect and to aggregate, rather than physical data. But Leontief’s price model is based on a ‘trick’: it is generally not coherent, unless the strong assumption is made that the interindustry matrix of direct and indirect quantities of labour incorporated per unit of physical output is stable over time. Fidel Aroche Reyes examines the link between Leontief’s equilibrium concept and his rather scarce writings on economic policy, such as the government programme addressing the consequences of the 1930 recession. Though Leontief remained mainly attached to the notion of equilibrium, the paper points to an evolution of Leontief’s thought on the role of these economic policies.

7The final article, by GianDemetrio Marangoni and Domenico Rossignoli, analyses the contributions of Richard Stone (1913-1991) to input-output analysis, for which he was awarded the Nobel Prize in 1984. Stone’s main aim was to combine theory and facts and he found in input-output analysis the tool for that project. His works are intimately tied to the positions he held during his career; for instance, he contributed to the UN programme which led to a standard system of national accounts. He developed new tools and extended the use of input-output analysis to new fields such as demography, education, health and environment.

8On the whole, this special issue of the Cahiers sheds light on the historical evolution of the input-output approach, from its very beginning with the Physiocrats (Schumpeter would have referred first to Cantillon) and the emergence of new fruitful ideas to its more contemporary applications. All along that evolution, some ideas have become more precise, and new tools have been elaborated for theoretical or applied purposes; also, some paths which were open, or at least suggested, by the founders have not been explored or were abandoned. It was not our ambition to cover the whole field of the history of input-output analysis and, for instance, none of the papers studies the Classical school or refers to Sraffa (but the previous special issue of the Cahiers was devoted to Sraffa and the Sraffian school). But the light shed on some innovative authors suffices to show that input-output analysis as we know it today is the result of a long conceptual endeavour with a complex history. Describing the trajectory of input-output analysis not only calls for references to the evolution of economic ideas: it also requires excursions into the role of social institutions and the State, into the progress of formalisation, and into changes of the techniques for collecting and treating data.