Teaching & Learning History of Economic Thought (HET): Some Observations

The following is a short reflection and response to the lectures, questions, and conversations at the recently concluded 3-day HET workshop at MIDS, Chennai. In personal conversations, many people thought that HET is about economic ideas that originated in a particular context. 

That is, Smith’s economics is a response to his sociopolitical context. And therefore, the implication is that Smith’s political economy be placed in a museum—an archaeological site that we visit occasionally. Another implication to this appears to be that HET is not relevant to contemporary thought because our context is different from that of Smith’s. 

Such an approach to HET, to me, makes it a rather dead subject. Consequently, in the economics curriculum, it serves other core papers such as micro and macro by providing it with context/history and thereby improving student learning/understanding. Yes, this is important, but it makes HET an instrumental subject. However, that, per se, is not an issue because all knowledge in one way or the other are instrumental. 

I see 3 problems with such a view. 

One, it is a reductionist approach because it reduces ideas to the context, be it intellectual (i.e., texts, speeches) or sociopolitical (i.e., laws, wars, conflict). How do we then account for human ingenuity and creativity? Also, how do we understand classics—that have a timeless quality? Or, are we saying that there is nothing in economics that may be applicable across time and space? [On the question of applicability of economic theory, see the discussion in Chapter 6 of my macro book.] 

The second problem is that such a reductionist view of HET inevitably succumbs to the linear view of intellectual progress. Wherein the ideas of Solow are better than Smith objectively speaking and that the ideas of Solow are more relevant to us because, in terms of calendar time, Solow’s work is closer to us than Smith’s. 

The third problem is that we are okay about marginalized ideas remaining forgotten. Studying ideas—texts written by women (and folks whose texts were not popular)—remain invaluable for contemporary thought and action. This perhaps depends on how comfortable we are about ignoring the ideas of our ancestors. (I am currently reading The Penguin Book of Feminist Writing edited by Hannah Dawson; the first text belongs to 1405 and the last one to 2020.)

HET: Understanding Economics

HET allows us to organize past ideas in a meaningful manner. The simplest organizer is that of calendar time. But ideas are forgotten, revived, exhumed, bolstered, expelled, popularized for a variety of reasons and so a simple chronological account cannot provide a sufficient historical account of economic ideas. 

We need to have other ways of organizing so that we understand not only the past better but also the present. Another organizing principle among historians of economic thought is that of ‘school of thought’ or ‘paradigms’. For instance, HET books discuss ‘classical’ and ‘neoclassical’ general equilibrium (Harvey & Gram 1980); ‘neoclassical’, ‘Keynesian’ and ‘Marxian’ (Wolff & Resnick 2012); ‘classical political economy’ and ‘supply and demand theories’ (Bharadwaj 1986). 

Many historians of economic thought, including me, reject the ‘neoclassical’ label. This is because it suggests that there is continuity between ‘classical’ (associated with economists such as Quesnay, Smith, Ricardo) and ‘neoclassical’ (associated with economists such as Say, Walras, Marshall). The analytically satisfactory label is ‘marginalist’—because of their reliance on concepts such as marginal utility, marginal cost, etc. 

HET tells us that competing ideas have always existed; we often only learn about those that have been popular/dominant. For instance, Ricardo disagreed with Say that exchange value is determined by use value. And today’s microeconomics textbooks teach us that commodity prices are determined by cardinal/ordinal utilities. When Keynes and Sraffa were writing, the economic ideas of Marshall were dominant and those of Smith and Ricardo were forgotten. HET allows us to understand that the evolution of ideas has been anything but linear. 

And today as well, research happens in all schools of thought—contrary to what is implied in mainstream textbooks on micro, macro, econometrics, labour. 

The study of HET

We study the world by dividing it into different parts; for instance, the physical and social worlds. Or the natural sciences and human sciences. Or physics and economics. Economics may be further sub-divided into micro and macro. Or labour and ecological economics. 

Within HET, scholars sometimes distinguish between ‘history of economic analysis’ and ‘history of economic thought’ where the former is a subset of the latter. We can find economic thought in Arthashastra but there is no evidence of any theorizing/analysis. 

Another division in HET is that between the internalists and externalists although I think that most of us operate somewhere in that spectrum. The internalists study economic ideas by focusing on previous economic ideas and on the logical framework of that ideas. For example, when studying Ricardo, we read his texts and the texts he was influenced by such as Smith’s Wealth of Nations. My 2021 article ‘On “effectual demand” and the “extent of the market” in Adam Smith and David Ricardo’ is an example of this. When an externalist studies Ricardo, they include his social and political context and interpret his ideas as responses to them. A good example of this is Timothy Davis’s Ricardo’s Macroeconomics: Money, Trade Cycles, and Growth (2005). A good biography warrants a synthesis of the externalist and internalist approaches. 

Summing-up

HET allows us to understand the ebb and flow in dominant paradigms. It makes us aware that history is replete with debates across as well as within paradigms. Indeed, debates spur knowledge production. While most economics textbooks suggest consensus, economics journals (both orthodox and heterodox) suggest dissensus. There are conceptual debates, refinements, revivals and contextual critiques, challenges, applications. Furthermore, adopting an HET perspective in the teaching of microeconomics and econometrics will provide the learner with a critical grounding in history, politics and philosophy. 

I thank Thair Ahmed for helpful comments.

Is there anything natural about prices?

This blog post is motivated by Ashish Kulkarni’s post, which is a response to Samrudha Surana’s substack entry, which in turn is a response to a question I had posed at the recently concluded HET conference organized at Azim Premji University, Bengaluru. And perhaps the process of reading and writing for this post will motivate me enough to get back to systematic blogging. 

According to the Oxford Dictionary, ‘natural’ means “not made or caused by humans”. Viewed this way, there is nothing natural about markets or governments. Both have been created/designed by humans. Consequently, the prices set in markets and the prices set by governments are in no way natural. Yet, marginalist economists (and adherents of the Austrian school) suggest that there is something natural or spontaneous about the prices that emerge in markets vis-à-vis those that are set or administered by governments. This is the mainstream view—propagated via introductory textbooks. 

This post critically engages with James Buchanan’s 1964 article ‘What Should Economists Do?’ published in the Southern Economic Journal as this forms the basis of the posts by Samrudha and Ashish.  The critical appraisal of Buchanan’s article is restricted to his misunderstanding of Adam Smith.

Buchanan’s misunderstanding of Smith

In the very first page of his article, Buchanan calls our attention “to a much-neglected principle enunciated by Adam Smith” (p. 213). The “principle which gives rise to the division of labor” is, quoting Smith, “the propensity to truck, barter, and exchange one thing for another”. And that its significance “has been overlooked in most of the exegetical treatments of Smith’s work.” 

Buchanan wants economics to be “the theory of markets” and not the “theory of resource allocation” (p. 214). As he writes,

Man’s behavior in the market relationship, reflecting the propensity to truck and to barter, and the manifold variations in structure that this relationship can take; these are the proper subjects for the economist’s study. 

Later in the essay, there is an inaccurate reference to Smith’s invisible hand (p. 217; see my moneycontrol article on Smith here). What Buchanan perhaps ignores or is unaware of is that Smith’s economics is one that emphasizes production, economic growth and development. Contrast Buchanan’s definition of economics provided above with that of Smith. 

Political oeconomy, considered as a branch of the science of a statesman or legislator, proposes two distinct objects: first, to provide a plentiful revenue or subsistence for the people, or more properly to enable them to provide such a revenue or subsistence for themselves; and secondly, to supply the state or commonwealth with a revenue sufficient for the public services. It proposes to enrich both the people and the sovereign. (Smith 1776, IV.1)

And to make sense of economic development, a theory of price is essential (for an elaborate account, see Section 2 of my chapter in The Anthem Companion to David Ricardo—available here).

In the tradition of Petty, Cantillon and Quesnay, Smith distinguishes between “natural prices” and “market prices”. In Cantillon, the corresponding terms are “intrinsic value” and “market prices”. It is important to keep in mind that both “natural prices” and “market prices” are theoretical in nature, with the former at a higher level of abstraction than the latter. If market prices were empirical in nature, there would not be a single market price but a spectrum of prices that vary according to the nature and quality of the commodity as well as the time and location of the market. 

Be it the market or the government, both have been created and designed by humans and will continue to be re-created and re-designed. This, Buchanan recognizes. As he writes, “A market becomes competitive, and competitive rules come to be established as institutions emerge to place limits on individual behavior patterns” (p. 218; emphases in the original). For him, the market is “the institutional embodiment of the voluntary exchange processes that are entered into by individuals in their several capacities. This is all that there is to it” (p. 219). This is where Buchanan goes astray. 

I ask: how voluntary is the process of exchange under capitalism? How voluntary is the process of exchange under patriarchy? How voluntary is the process of exchange under the caste system? Smith is very cognizant of the fact that employers have more power than workers in capitalist societies. Smith is aware that big corporations (with/without support from the government) have more power than small entrepreneurs. Buchanan is unable to view power as a structural feature of our economic system—unlike Smith. One reason for the inability could be his adherence to an extreme version of methodological individualism. 

Conclusion

To conclude, the spaces wherein exchanges are truly voluntary for all parties, I think, are very less. Household? Firm? Village? City? International trade?

Political economy, in the work of Adam Smith, recognizes social classes and social power. And it is this recognition that will enable us to design better markets and governments. And this means better designs for pricing commodities, determining wages, setting interest rates, improving employment levels, and recharging our environment.  

Cheryl Misak’s Ramsey: Notes on his association with Harrod, Dobb, and Sraffa

Frank Ramsey was in Cambridge at the same time as John Maynard Keynes, Arthur Pigou, and Piero Sraffa, some of the most influential economists of the twentieth century. Ramsey died on 19th’January 1930, six years before The General Theory of Employment, Interest and Money’(1936), ten years after The Economics of Welfare(1920), and around the same time as the central propositions in Production of Commodities by Means of Commodities’(PCMC) was worked out. While an earlier blog post had examined Ramsey’s views on the rate of interest, the present one narrates his intellectual association with Maurice Dobb, Roy Harrod, and Sraffa, and a forthcoming one will focus on his intellectual association with Pigou and Keynes. The present and future posts are primarily based on Cheryl Misak’s new biography of Ramsey (2020, Oxford University Press). This post supplements the observations found in Misak’s Ramseywith those found in the books on Harrod and Sraffa published as part of the Palgrave Macmillan ‘Great Thinkers in Economics’ series by Esteban P’rez Caldentey (2019) and Alessandro Roncaglia (2009) respectively and the book on Dobb by Timothy Shenk (2013) published as part of the ‘Palgrave Studies in the History of Economic Thought’ series.

HARROD

While Harrod today is probably most well-known for his contributions to growth theory, he made important contributions to the fields of trade cycle theory, imperfect competition, and international economics. While there are 14 references to Harrod in Misak’s Ramsey, there are only eight references to Ramsey in Caldentey’s Harrod’(2019). [If there are two or more mentions of Harrod in a single page, I treat that as one reference.]

Ramsey and Harrod were friends (p. xxxi). Ramsey had known him ‘since 1922, when Harrod spent part of the year at King’s. Frank had taken Harrod under his wing then, introducing him to [G. E.] Moore and others’ (p. 195). After Ramsey was elected a fellow of King’s College, Cambridge in 1924, he renewed his friendship with Harrod, ‘a young left-leaning economics don at Oxford ‘ and they travelled between Oxford and Cambridge for intellectually rich weekends’ (p. 195). Caldentey mentions Harrod experiencing ”tremendous stimuli” after meeting Ramsey in Cambridge as opposed to his ‘frustrating Oxford experience’ (p. 10).

Although Harrod’s paper on the concept of marginal revenue curve was eventually published in the Economic Journal’as ‘Notes on Supply‘ (1930), on Ramsey’s advice, its editor, Keynes, had initially rejected the article in 1928 and had asked for revisions on the treatment of cartels (p. 305). In the meantime, according to Harrod, others had ‘discovered’ his concept and therefore he failed to receive credit for inventing it. Caldentey informs us that Harrod’s initial paper submitted in 1928 was titled ‘Notes on Monopoly and Quasi-competition’ wherein ‘he derived the increment of aggregate demand curve which was later re-baptized, the marginal revenue curve by Joan Robinson’ (p. 18). Moreover, Caldentey notes that in the foreword to the first edition ofThe Economics of Imperfect Competition’(1933), Robinson acknowledges the following individuals for teaching her about the marginal revenue curve: C. H. P. Gifford, P. S. Sloan, and T. O. Yntema (p. 101, n. 30). Also see Caldentey (pp. 18-19, 100-1) for a recounting of the refereeing episode between Ramsey and Harrod, which also makes reference to the three-volume work, The Collected Interwar Papers and Correspondence of Roy Harrod’published by Edward Elgar in 2003 under the editorship of Daniele Besomi.

DOBB

Dobb’s contributions to Marxist economics are well established. I was introduced to his work during my Master’s in Economics at the University of Hyderabad where we read selected parts from Theories of Value and Distribution Since Adam Smith: Ideology and Economic Theory’(1973). His collaboration with Sraffa in editing and producing The Works and Correspondence of David Ricardo’has also been noteworthy. In Shenk’s Dobb, surprisingly, there is not even a single reference to Ramsey while there are 21 references to Dobb in Misak’s Ramsey.

Dobb was Ramsey’s friend from their undergraduate days (1920-3) at Cambridge (p. 94). They had started their degrees at the same time (p. 79); Ramsey enrolled for mathematics at Trinity College and Dobb for economics at Pembroke College. And during this time, ‘Dobb had considerable influence on Ramsey, both by engaging with him about the kind of socialism that would be best, and by introducing him to workers’ meetings’ (p. 299). While Ramsey was finishing his secondary education at Winchester in 1920, in addition to reading the economics books by Alfred Marshall and Keynes, he also read works by Karl Marx and V. I. Lenin (p. 47). However, according to Misak, it isn’t clear how much they associated with each other after completing their undergraduate studies (p. 87).

In his 1925 doctoral thesis, Dobb tried to bring Marx and Marshall together (p. 300). Shenk points out that Dobb had been trying to synthesize Marx and Marshall even before he started his PhD at the London School of Economics (LSE): ‘Dobb, too, sought to integrate marginalism with classical political economy, but with Marx substituting for Ricardo as the standard-bearer for political economy. ‘ In Dobb’s vision, Marx appears as a theorist of the social, Marshall of the economic’ (p. 36). Dobb’s PhD thesis was published in 1925 as Capitalist Enterprise and Social Progress, and Shenk provides us with its outline: ‘Dobb dedicated the first section to economic theory, the second to economic history, and the third to evaluating contemporary economic practices from the perspective developed over the course of the book’ (p. 38). Since Ramsey ‘was considered (and considered himself) a socialist’ (p. 301), Misak argues that Ramsey’s use of utility theory in his paper on optimal saving needs to be seen in the light of the synthesis Dobb had attempted between Marxism and marginalism (p. 302).

Ramsey’s view of the use of mathematics in economics was similar in spirit to that of Dobb (and Keynes): ‘Like Dobb, he thought that one ignores mathematics at one’s peril, for the mathematics has to be right in order for progress in the real world to be made. And some real-world issues are going to be solvable by doing the maths’witness Ramsey’s response to the Douglas Proposals. But he did not think that the mathematician could step in and solve all problems. He agreed with Keynes that we mustn’t be so taken with the precision of mathematics that we erase the outlines of the very thing we are examining. As Ramsey so often put it, one mustn’t be woolly, but one mustn’t be scholastic either’ (p. 326).

SRAFFA

Sraffa has made significant contributions to price theory and capital theory and deserves high praise for his editorship of the collected works and correspondence of Ricardo. I have written on Sraffa earlier.’ While there are only two references to Ramsey in Roncaglia’s Sraffa, there are 18 references to Sraffa in Misak’s Ramsey. Given this scant attention to Ramsey in Roncaglia’s Sraffa, I make use of Heinz Kurz and Neri Salvadori’s essay ‘Sraffa and the Mathematicians: Frank Ramsey and Alister Watson’ first published in 2000 in Piero Sraffa’s Political Economy: A Centenary Estimate, a volume edited by Terenzio Cozzi and Roberto Marchionatti (as republished in Classical Economics and Modern Theory: Studies in Long-Period Analysis, an edited volume by Kurz and Salvadori in 2003).

As Sraffa writes in the preface to his 1960 classic, ‘the central propositions had taken shape in the late 1920’s’ (p. vi). In the following paragraphs, he expresses his gratitude to Ramsey (along with Alister Watson) for ‘invaluable mathematical help’at different periods’, and his greatest debt is reserved for A. S. Besicovitch. Kurz and Salvadori examine Sraffa’s diaries to identify the number of his meetings with Ramsey; according to the dairy entries, they met twice in 1928 (28 June and 11 November) and thrice in 1929 (10 May, 30 May, and 29 November) (p. 190).

The main outcome of their first meeting is capably captured by the following excerpt from Kurz and Salvadori: ‘At first Sraffa appears not to have explicitly distinguished between the quantity and the price or value of a commodity, a fact to which Ramsey immediately seems to have objected. Sraffa then appears to have introduced the distinction during the conversation with Ramsey’. Ramsey then reformulated the system first by putting the system of homogeneous linear equations in its canonical form, then by setting the determinant of coefficients equal to zero in order to get a non-trivial solution’ (p. 197). The key aspects of this meeting are not as ably captured in Misak and it is also incorrectly stated that Sraffa’s famous work related to ‘the determination of prices and’outputs’ (p. 305; emphasis added) whereas the size and composition of output is a given in PCMC.

Ramsey died in the middle of writing his book on truth and probability. Misak draws attention to the fact that after his death the philosopher R. B. Braithwaite published some of Ramsey’s essays in 1931 under the title The Foundations of Mathematics and Other Logical Essays’(p. 273). According to Misak, John von Neumann and Oskar Morgenstern had reached very similar conclusions in their 1944 Theory of Games and Economic Behaviour’(p. 274). And Misak further notes that, the similarity was so striking that John Hicks went to the extent of writing to Sraffa on 3rd’September 1960 asking if Ramsey’s ideas were transmitted to von Neumann through him (and his ‘mathematical friends’) but Sraffa didn’t reply (p. 274; although a draft of Sraffa’s response is available, it is not clear whether he actually sent it to Hicks). However, after consulting the letter (available here), it is clear that Hicks is actually asking Sraffa how von Neumann arrived at a similar theoretical outlook as Sraffa; and it is not about the similarities between Ramsey and von Neumann as Misak claims.

ON VALUE THEORY

This blog post ends with some critical observations on Ramsey’s engagement with value theory. According to Misak, Ramsey ‘blended neo-classical economics and socialism’ (p. 303). Despite his ‘scepticism about the utility theory of value’, as Misak notes, ‘his two famous papers were written in the neo-classical framework of individuals maximizing utility’ (p. 302). The two important pieces of evidence Misak provides for the former are given in the following excerpt: ‘In his 1924 Apostles paper, he castigated Mill for putting all his eggs in the utilitarian basket. During 1927’28, when his two important papers in economics were written, he was also working on a book in which he hoped to carve out a subtle, naturalist theory of value’ (p. 302). Since this book was not completed, it is difficult to state whether Ramsey would have stood closer to the neoclassical or the classical theory of value. However, Sraffa’s position on the marginalist (or neoclassical) value theory is clear: it is futile. Therefore, unlike Misak, who writes that ‘It’s clear that Ramsey,’like’Dobb and Sraffa, had a complex, pluralistic, view of value’ (p. 302; emphasis added), I would be very reluctant to conjecture a similarity between Ramsey and Sraffa on the question of value theory.

 

Revisiting J. H. Clapham’s ‘Empty Economic Boxes’

This blog post revisits the economic historian J. H. Clapham’s1922 classic paper ‘Of Empty Economic Boxes‘ published in The Economic Journal, and raises some critical questions about the continued use of constant returns to scale (CRS hereafter) assumption in marginalist (or neoclassical) microeconomics and macroeconomics. In 1926, Piero Sraffa took Clapham’s 1922 paper as a starting point to mount a more devastating logical critique of Marshallian notions of increasing returns and the representative firm; this was published as part of a symposium in the Economic Journal.

What is returns to scale’ According to marginalist economics, the technique of producing a commodity may be represented by a functional relationship between inputs (say, k’and l) and output (say, y): y’= f(k,l). If all the inputs are multiplied by a positive scalar m, and the resultant output is expressed as mr’y, then r’represents the magnitude of the returns to scale. If r = 1, the technique exhibits CRS, if r < 1, it exhibits diminishing returns to scale (DRS), and if r’> 1, it exhibits increasing returns to scale (IRS).

Despite the ‘advances’ in mainstream economics research, the marginalist theory of value and distribution still requires the CRS assumption (and the diminishing returns to a factor assumption) to make several key claims. The aggregate production function employed in the Solow growth model is assumed to exhibit CRS. And the Solow growth model forms the core of supply-sidegrowth accounting exercises which are used to make policy prescriptions (for a critique of one such exercise for the Indian economy, see Joshi & Thomas 2013).

The central argument in Clapham’s article is that the categories of diminishing returns, constant returns, and increasing returns industries are ’empty economic boxes’. In other words, from the standpoint of actual economies, these categories lack empirical and historical content. Consequently, industries cannot be classified into one or the other box a priori.

Clapham asks: what does AC Pigou (in his Economics of Welfare) mean when he writes ‘when conditions of diminishing returns prevail’ (p. 305)’ According to Clapham ‘constant returns…must always remain a mathematical point, their box an empty one’ (p. 310). He acknowledges that different kinds of returns have a ‘logical’ and ‘pedagogic value’ which ‘goes so prettily into graphs and equations’ (p. 312). How can we then use this framework to draw policy conclusions given the inability to classify industries a priori into constant, diminishing, and increasing returns’

The following observation by Clapham is insightful and worth thinking about further. He writes that diminishing returns must be balanced with increasing returns to arrive at constant returns (p. 309). Surely, this makes no conceptual sense and neither does it have any basis in empirical reality. As Clapham puts it, with CRS ‘the conception of the balance of forces, man’s organization versusNature’s reluctance, was worked out’ (p. 309). In other words, is CRS an expression of the balancing of the symmetrical forces of IRS (‘man’s organization’) and DRS (‘Nature’s reluctance’)’ For a visual representation, see the images below. If so, it would add to the symmetrical concepts found in the marginalist toolbox, most notably that of supply and demand. However, beyond the ease of exposition symmetry provides us, is it really how the actual world works’

Source: meritnation.com

CRS, DRS, and IRS posit an a priori functional relationship between labour (L) and capital (K), the ‘factors of production’ and output (Y) for an individual firm and for an economy: Y=f(L,K). While the idea underlying the production function, whether industry-level or aggregate-level, that outputs are produced by inputs is commonsensical and intuitive, its expression as a mathematical function isn’t as benign. Since marginalist economics requires continuous functions (often, of a monotonic nature) to ensure the existence of equilibrium, the ‘f’ is able to map infinitesimal combinations of Land Kto a unique Y. This ‘one-way street’, to use Sraffa’s phrase in his 1960 classic Production of Commodities by Means of Commodities(see my blog post Sraffa), between ‘factors of production’ and output is conceptually unsatisfactory because it misses a fundamental aspect about modern economies: the structural interdependence between inputs and outputs. In addition, it assumes that capital goods (K) are infinitely divisible, a very difficult assumption to uphold.

John Eatwell (2008; first published in 1987), in his entry on ‘returns to scale’ published in The New Palgrave Dictionary of Economics, also notes the apparent symmetry between IRS and DRS but points out its spuriousness. While there is no evidence of functional relationships in Adam Smith and David Ricardo, Smith’s discussion of division of labour, capital accumulation, and economic growth indicates that he recognised scale-enabled technological progress and Ricardo recognised diminishing returns to land, a non-reproducible input in production. Subsequently, Alfred Marshall, in his Principles of Economics, ‘attempted to formulate a unified, symmetric, analysis of returns to scale which would provide the rationale for the construction of the supply curve of a competitive industry, derived in turn from the equilibria of the firms within the industry’ (Eatwell 2008, p. 140). This point was initially noted by Sraffa 1926, and later much more thoroughly investigated also by Krishna Bharadwaj (1978).

It is well understood that the question of returns to scale is important in the construction of the supply curves which are integral for the marginalist price theory. Therefore, a thorough critical study of mainstream price theory and a renewal in the interest in rival price theories (found in Ricardo, Marx, Sraffa, and Kalecki, among others) are warranted. This is crucial because it is value or price theory which provides us with the economic possibilities a competitive economy generates. If it generates unemployment and worsens inequality, we know that intervention of a particular kind is necessary. However, if it generates full employment and reduces inequality, then it supports the idea of making markets more competitive and reducing government intervention.

REFERENCES

Clapham, J. H. (1922), “Of Empty Economic Boxes.”‘The Economic Journal,’vol. 32, no. 127, pp. 305-14.

Eatwell, John (2008), ‘Returns to Scale’. In: Durlauf S.N., Blume L.E. (eds.) The New Palgrave Dictionary of Economics. London: Palgrave Macmillan.

Sraffa, Piero (1926), “The Laws of Returns under Competitive Conditions.”‘The Economic Journal,’vol. 36, no. 144, pp. 535-50.

Acknowledgement

I thank Mohib Ali for his helpful comments.