The Passage of Time, Capital, and Investment in Traditional and in Recent Neoclassical Value Theory

New paper by Fabio Petri published in Œconomia. From the abstract:

With the shift from traditional analyses where capital is a single value factor of variable ‘form’ to the neo-Walrasian versions, general equilibrium theory has encountered new problems pointed out by P. Garegnani (1976, 1990): impermanence problem, price-change problem, substitutability problem radically question the right to consider neo-Walrasian equilibria as approximating the actual path of real economies. The paper briefly summarizes these problems and then concentrates on a fourth problem, the savings-investment problem, arguing that neo-Walrasian general equilibrium theory assumes that investment is adjusted to full-employment savings but cannot justify this assumption. The attempt to justify it in intertemporal general equilibrium through the tâtonnement is subjected to a new criticism: it is shown that the tâtonnement assumes Says’ Law all along the adjustments, and determines investment in a way that would crumble if it were not assumed that consumers determine their demands for consumption goods on the basis of an assumption of full employment incomes, which is not justified outside equilibrium, and was not assumed in traditional analyses. This reinforces the absence of reasons to view neo-Walrasian equilibrium paths as sufficiently approaching actual paths. It is concluded that behind the reference to intertemporal equilibrium as the microfoundation of macro analyses there is a continuing faith in traditional neoclassical time-consuming adjustment mechanisms, based on the old and untenable conception of capital that the shift to neo-Walrasian equilibria intended to do without.

Full paper available here.

John Eatwell on the theoretical lessons from the crisis

It's from 2012, but still very much relevant. Short and to the point about the limitations of the mainstream to understand the crisis. I would put less emphasis on the Sonnenschein–Mantel–Debreu theorem, and more on the Sraffa-Garegnani critique of General Equilibrium, but that's a detail. He is correct in pointing out to Keynes' Principle of Effective Demand (PED), and to the insidious role of finance.

Yes, The Cambridge Capital Controversies Do Matter

From Unlearning Economics:

I rarely (never) post based solely on a quick thought or quote, but this just struck me as too good not to highlight. It’s from a book called ‘Capital as Power’ by Jonathan Nitzan and Shimshon Bichler, which challenges both the neoclassical and Marxian conceptions of capital, and is freely available online. The passage in question pertains to the way neoclassical economics has dealt with the problems highlighted during the well documented Cambridge Capital Controversies:

The first and most common solution has been to gloss the problem over – or, better still, to ignore it altogether. And as Robinson (1971) predicted and Hodgson (1997) confirmed, so far this solution seems to be working. Most economics textbooks, including the endless editions of Samuelson, Inc., continue to ‘measure’ capital as if the Cambridge Controversy had never happened, helping keep the majority of economists – teachers and students – blissfully unaware of the whole debacle.

A second, more subtle method has been to argue that the problem of quantifying capital, although serious in principle, has limited practical importance (Ferguson 1969). However, given the excessively unrealistic if not impossible assumptions of neoclassical theory, resting its defence on real-world relevance seems somewhat audacious.

The second point is something I independently noticed: appealing to practicality when it suits the modeller, but insisting it doesn’t matter elsewhere. If there is solid evidence that reswitching isn’t important, that’s fine, but then we should also take on board that agents don’t optimise, markets don’t clear, expectations aren’t rational, etc. etc. If we do that, pretty soon the assumptions all fall away and not much is left.

However, it’s the authors’ third point that really hits home:

The third and probably most sophisticated response has been to embrace disaggregate general equilibrium models. The latter models try to describe – conceptually, that is – every aspect of the economic system, down to the smallest detail. The production function in such models separately specifies each individual input, however tiny, so the need to aggregate capital goods into capital does not arise in the first place.

General equilibrium models have serious theoretical and empirical weaknesses whose details have attracted much attention. Their most important problem, though, comes not from what they try to explain, but from what they ignore, namely capital. Their emphasis on disaggregation, regardless of its epistemological feasibility, is an ontological fallacy. The social process takes place not at the level of atoms or strings, but of social institutions and organizations. And so, although the ‘shell’ called capital may or may not consist of individual physical inputs, its existence and significance as the central social aggregate of capitalism is hardly in doubt. By ignoring this pivotal concept, general equilibrium theory turns itself into a hollow formality.

In essence, neoclassical economics dealt with its inability to model capital by…eschewing any analysis of capital. However, the theoretical importance of capital for understanding capitalism (duh) means that this has turned neoclassical ‘theory’ into a highly inadequate took for doing what theory is supposed to do, which is to further our understanding.

Apparently, if you keep evading logical, methodological and empirical problems, it catches up with you! Who knew?

Sraffa and the Marshallian system

(Sraffa circa 1976)

G. L. S. Shackle argues in The Years of High Theory that ‘there began in the mid-1920s an immense creative spasm, lasting for fourteen years until the Second World War, and yielding six or seven major innovations of theory, which together have completely altered the orientation and character of economics’ (Shackle, 1967, p. 5). However, by 1967, the two most important developments of this period—Keynes’s principle of effective demand and Sraffa’s criticism of the marginalist theory of value—were rapidly fading from the main corpus of mainstream theory.

The relative ease with which neoclassical economics reasserted its main conclusions is, in fact, explained by Shackle’s account of those years. First, Sraffa’s critique of the Marshallian theory of value is seen only as a step in the development of the theories of imperfect competition by Joan Robinson and Edward Chamberlin. Second, Keynes’s General Theory is seen as stating that unemployment results from the existence of uncertainty and irrational expectations (Shackle, 1967, p. 129). Both developments can be interpreted as asserting that market imperfections render neoclassical theory, although internally coherent, irrelevant for the analysis of the real world.

Also Shackle’s failure in 1967 — well after the publication of Production of Commodities — to acknowledge the importance of the revival of classical political economy to the debates of the 1930s represents a serious inadequacy of his interpretation of ‘the years of high theory’.

Before getting into Sraffa's critique of Marshall, it is worth noticing that Sraffa came to economics via monetary economics, like Ricardo and Keynes. His dissertation for the Law Degree, L’Inflazione Monetaria in Italia Durante e Dopo la Guerra (subscription required), dealt with postwar inflation and the return to the Gold Standard, the same topic of Keynes’s Tract on Monetary Reform. According to Eatwell and Panico (subscription required), in the analysis of the asymmetric effects of inflation and deflation Sraffa reveals the heterodox character of his position, more akin with the works of the classical authors and Marx than the conventional marginalist analysis. The notion that social conflicts and monetary factors determine the normal real wage was part of Sraffa’s analysis, although several elements of his analysis were still conventional, e.g. the acceptance of the Quantity Theory and of the Purchasing Power Parity theory.

Sraffa’s criticism of the Marshallian theory of supply represents an analogous situation, in the sense that some elements of the conventional marginalist views were still present. Marshall’s or Sraffa’s dilemma (which appears in Sraffa's 1926 paper) refers to the incompatibility between increasing returns and perfect competition. It is a long period problem. Sraffa’s critique can be summarized in the following way. First, rising costs derive from diminishing returns to substitution, and, therefore, in the general case where there are no fixed factors, increasing costs do not seem to exist. Secondly, increasing returns are incompatible with perfect competition. In the long period, when the firm cannot experience marginal costs arising from the existence of some fixed input, there can be no diminishing returns. Replication is always possible, except for the case of indivisibilities. In addition, Sraffa showed that increasing returns to scale are inconsistent with the notion of perfect competition.

In the case of increasing returns, the average cost is decreasing, implying that the marginal cost is below average variable cost, and, hence, there is no infinite, non-zero solution for the profit maximization problem. In other words, there is a tendency for the firm to expand to infinite size. Sraffa’s argument proves the failure of perfectly competitive assumptions to determine any equilibrium of the individual firm. Two alternatives are opened by Sraffa’s critique of Marshallian theory. If it is not legitimate to treat average cost as either increasing or decreasing within the framework of perfect competition, we are left with the result that the only satisfactory assumption is that of constant returns. On the other hand, ‘everyday experience shows that a very large number of undertakings work under conditions of individual diminishing costs’ (Sraffa, 1926, p. 543), which suggests that we should instead abandon the notion of perfect competition.

Sraffa considered the imperfect competition approach to be the only logical way to develop the theory of value along Marshallian lines. However, he showed no inclination to pursue this solution, and he appears to have already been working toward the revival of the classical approach. The origins of this project can be traced back to his early draft of the opening propositions of the Production of Commodities, which he asked Keynes to read in 1928 (Sraffa, 1960, p. vi). The reasons for not pursuing imperfect competition were never quite explained by Sraffa, but are fairly reasonable to infer (note that in Cambridge it was two of his students, Richard Kahn and Joan Robinson, that developed the imperfect competition theory).

Note that in order to obtain partial equilibrium, which is what the Marshallian model presumes, one must assume that prices in a particular industry are not affected by and do not affect the prices in other industries. Hence, externalities have to be internal to the industry, since otherwise production in one sector would affect the prices in other industries [perfect competition in partial equilibrium, the U-shaped cost curves and the equilibrium at the minimum with marginal cost equal marginal revenue, require also that externalities are external to the firm, since if they weren't the firm would became a monopolist; of course externalities that are internal to an industry and external to firms are an empty set]. That seems to be a dead end. Sraffa was already interested in the determination of long term prices. By this time, the summer of 1927 when he was preparing his ‘Lectures on Advanced Value Theory’ that he gave from 1928 until 1930, it was already clear to him that he needed to start from classical preocupation of determining relative prices and one of the distributive variables (the rate of profits or wages) strictly in material terms, that is, the quantities of labor and commodities needed to produce commodities.

For further on Sraffa's critique of Marshall see Gary Mongiovi's paper here (subscription required). For a general critique of Shackle's stance in the history of 'the years of high theory' read this one. For the implications of Sraffa's 1960 book for economics go to this old post (yes on the capital debates!).

The capital debates: A brief introduction

Teaching on the capital debates this and last week. So here are some thoughts, based on my class notes and the required readings (see below). The capital debates remain a puzzling chapter in the history of economic ideas. Nearly everyone accepts that the British (as opposed to the Massachusetts) Cambridge won the debate, something Paul Samuelson acknowledged early on.[1] Yet, no one seems to grasp the full implications and relevance of the debate itself. Typically it is assumed that the capital debates relate simply to problems of aggregation, and that the use of aggregate production functions and aggregative measures of capital are still justifiable, for simplicity’s sake. However, contrary to this viewpoint the capital debates did not rest upon the possibility of building aggregate measures.

The capital debates are associated with the very notion of capital. Classical political economy authors, from William Petty to Karl Marx, including Quesnay, Smith and Ricardo, treated the process of production as a circular one. In this context, capital is a produced means of production,[2] rather than a factor of production used in the process of obtaining final goods. The most important result of the capital debates is that, once capital is defined as produced means of production, there is no direct relation between the relative abundance or scarcity of the means of production and its remuneration. Distribution, in other words, is not governed by supply and demand.

Since the Marginalist Revolution, and the rise of the so-called neoclassical school, the notion that relative prices are determined by supply and demand, and that these reflect the relative abundance or scarcity of all goods and services – including factors of production – became consensual. As a result, the supply and demand for capital became the determination for the remuneration of capital. The more abundant is capital, the lower its remuneration, and vice versa if it is scarce. Conflict has no role to play in the determination of distribution, and social classes vanished entirely from analysis.

Additionally, substitution leads to the full utilization of resources and their optimal allocation. If capital is scarce and expensive, and labor abundant and cheap, economic agents substitute labor for capital and fully utilize labor. Thus, despite the abundance of labor, its relative cheapness, through the principle of substitution, leads to full employment. Indeed, unhampered markets do lead to the veritable best of all possible worlds.

It is the logic of the principle of substitution, based on relative scarcities that the capital debates shattered. Contrary to the neoclassical parable, the capital debates showed that it is not generally possible to obtain a univocal relation between remuneration and relative scarcity. For example, assume that we have two commodities produced with capital and labor, and that one can be said to be univocally more capital abundant than the other. In this case, as capital becomes more abundant the profit-to-real-wage ratio will fall, more capital will be used, and more of the capital-intensive good will be produced. However, it is possible that one good would be more capital intensive at high levels of the profit-to-real-wage ratio, and that the other becomes the capital intensive good at lower levels of the same ratio. That is, we would have factor intensity reversal. In the instance of factor intensity reversals, the conventional relation between factor scarcity and relative prices breaks down.

In this situation, it would be possible that as the profit-to-real-wage ratio falls, more labor will be used, and more of the labor-intensive good will be produced. In other words, there would be reverse capital deepening and a lower rate of profit associated with a reduction in the use of capital. Substitution moves in the wrong direction, so to speak, and more of the scarce factor is demanded. A simple algebraic exercise may help understand the point.

Let’s assume that there are two methods of production, associated to the manufacture of capital (iron) and consumption (corn) goods respectively. The prices are determined by:

(1) pc=wlc+rpkkc
(2) pk=wlk+rpkkk

where the subscripts refer to consumption and capital, l and k are the technical coefficients of production, and w and r are the real wage and rate of profit. Using pc as a numeraire and solving for pk we obtain:

(3) pk=(1-wlc)/rkc

From (3) into (2) we get:

(4) [(1-wlc)/rkc]=wlk+rkk[(1-wlc)/rkc]

Simplifying, and solving for w we find:

(5) w=(1-rkk)/[lc+(lkkc-lckk)r]

If the expression in the small parenthesis in the denominator is equalized to zero we obtain a wage-profit frontier that is linear. This assumption is what Samuelson (1962, p. 225, n. 7) refers to as the equi-proportional assumption. Figure 1 shows the choice of technique under this assumption.

Figure 1

The firm chooses the highest rate of profit for a given real wage, which implies that as the rate of profit falls the firm must choose the more capital intensive (b in this case). In this case, the neoclassical parable works; there is an inverse relation between factor intensity and its remuneration.

Once, the assumption of equi-proportional capital to labor ratios in the machine and consumption sectors (which would mean in Marxist terminology the same organic composition of capital in both sectors) is dropped the wage-profit frontier is not linear anymore. If we assume that the capital goods sector is more capital intensive than the consumption sector then the wage-profit frontier will be concave (as shown in Figure 2).

Figure 2

In this case, we have two switches; at high levels of the rate of profit the firm choose technique a, which is more labor-intensive, and as the rate of profits falls it switches to b the capital-intensive one as prescribed by neoclassical economics. However, at even lower levels of the rate of profit, the firm switches back to the more labor intensive technique. Reswitching and reverse capital deepening, hence, result from the dismissal of the equi-proportionality assumption, which is what one would expect in a world with several goods.

The implications for neoclassical theory cannot be overstated. First and foremost, there is no relation between relative scarcity and the remuneration of factors of production, and, as a result, distribution is not simply the product of market forces. Further, there is no guarantee that all resources will be fully utilized.[3]

It must be noted that, even though the capital debates are fundamentally about the logical coherence of the neoclassical approach, the results of the capital debates have important empirical implications. Neoclassical theory makes strong predictions vis-à-vis substitution effects and the relation between relative scarcity and remuneration. Yet the capital debates suggest that some of those predictions might not be consistent, and, as a result, the absence of those relations might be expected in the real world.

The most obvious prediction is the inverse relation between investment (capital intensity) and the rate of interest (its remuneration). As it is well known, there is little evidence that investment is sensitive to variations in the real rate of interest. In a rare survey of the empirical literature on the determinants of investment Robert Chirinko (1993, p. 1906) argues, “[T]he response of investment to price variables tends to be small and unimportant relative to quantity variables.” In other words, interest rates have little effect on gross capital formation, and the substitution effects that imply that agents use the cheaper factor of production are not operative. Further, the empirical evidence suggests that investment reacts to quantity variables, meaning the level of activity. This suggests that the income effects tend to be larger tahn substitution effects and that a firm facing less demand will not buy capital goods, even if the interest rate is low. These results underscore the empirical relevance of the capital debates.[4]

Similarly, the capital debates highlighted the futility of using the aggregate production function to measure the growth and productivity performance of real economies. The theoretical problems with the aggregate production function, associated to the notion of capital as a scarce resource, are compounded by the impossibility of disentangling it from the identity of income with the structure of the functional distribution of income (Felipe and Fisher, 2003). In other words, if one runs a regression of income on capital and labor, as is often done by those using a production function, it necessarily follows that income grows because capital and labor grow. Furthermore, changes in income distribution also affect income growth, as total income (net of taxes) is by definition the wage multiplied by labor utilized in production plus capital multiplied by its remuneration.

In this way, the capital debates demolished the theoretical foundations of neoclassical economics, and provided significant empirical evidence that those neoclassical models and their resultant policy prescriptions should be viewed with a healthy measure of skepticism.

Faced with the impossibility of using both the notion of aggregate capital and the principle of substitution, neoclassical economics opted to apply the principle of substitution to each kind of capital good taken as a distinct factor of production, by using the Arrow-Debreu model of intertemporal general equilibrium (Garegnani, 1976; Milgate, 1979). Even though the idea of intertemporal equilibrium, in which capital is treated as a vector of heterogeneous capital goods, was first developed by Eric Lindahl and then popularized by John R. Hicks in the 1930s, and used by Arrow and Debreu in the 1950s, it was only after the capital debates that it came to be dominant within the mainstream.

The problem with the use of heterogeneous capital goods is that it implies a change in the traditional method of economics. Normal equilibrium positions are associated to a uniform rate of profit; however, when dealing with heterogeneous capital goods that are not substitutable between each other, it becomes necessary to discard the notion of long run equilibrium. In Arrow-Debreu models all prices are short run prices, associated to differential rentals for each capital good, and any change in the data of the system – preferences, technology, and information for given initial endowments – affects the direction to which the economy adjusts (Petri, 2003).

In other words, the forces of competition that lead capitalists to those sectors with higher remuneration and establish a uniform rate of profit do not operate in the Walrasian world.[5] Hence, the Walrasian models are incapable of ascertaining tendencies in real economies, a defect that is not mitigated with the introduction of imperfections (Stiglitz, 1993, p. 109), which Stiglitz calls the post-Walrasian and post-Marxist paradigm. Far from increasing the realism of the model, the casting about of such lifelines only complicates the results of an exceptionally unrealistic one.

Information imperfections, and other related imperfections like price rigidities or lack of rationality, once introduced leave the Arrow-Debreu model unable to produce Pareto efficient solutions, or even market equilibrium, since some markets may not exist. Additionally, the introduction of imperfections renders the aggregative model prone to suboptimal outcomes. Suboptimal results in the presence of imperfections suggest that in their absence markets would still produce optimal outcomes.[6]

Some authors tend to confuse the imperfectionist arguments, and the implicit support that they provide for policy intervention, as a break with orthodoxy. While it is clear that they provide space for flexibility in policy advice, they remain firmly based on orthodox grounds.[7] The capital debates, in contrast, showed that unhindered markets, free of imperfections of any type, do not lead to market efficiency in general.

Faced with the logical problems that neoclassical aggregative models are riddled with on the one hand, and the irrelevance of general equilibrium models on the other, neoclassical economists did what any rational agent would do: disregard the critiques and in so doing, their deleterious results, and proceed as if nothing had happened. However, an innovative, if not peculiar, development generated a curious division of labor within neoclassical economics. Aggregative models were deployed for the purposes of teaching and policymaking, while the Arrow-Debreu model became the retreat of neoclassical authors when questioned about the logical consistency of their models. In this response, a harsh tradeoff between logical consistency and relevance was cultivated in the very core of mainstream economics.

The degree of fragmentation – as Roncaglia (2005, p. 468) so aptly expresses it – and confusion in the mainstream today is the result of such inconsistency at the core of economics, and not uniquely, as is frequently asserted, because of the demise of the Keynesian consensus. The collapse of the certainties provided by the old aggregative neoclassical model has brought about an often cynical defense of market-oriented policies for their own sake. The return of Vulgar Economics, which “sticks to appearances … [and] believes that ‘ignorance is a sufficient reason’” (Marx, 1867, p. 307) is complete.

Notes:
[1] See Samuelson (1966). A typical position is that of Robert Lucas (1988, p. 36) who notes the victory of the British argument, and yet remains oblivious to the problems of using the aggregate production function in the same paper.

[2] For Marx (1867, p. 189) capital also involved a social relation between the owners of the means of production and those forced to sell their labor power. For him, capital “can spring to life, only when the owner of the means of production and subsistence meets in the market with the free laborer selling his labor-power.”

[3] Both results are important, for example, for the Keynesian possibility of unemployment equilibrium. Keynes’ (1936, p. 243) emphasis on the unimportance of the natural rate of interest not only implies that the supply and demand for capital (loanable funds) do not determine the equilibrium rate of interest, but also that the conventional rate of interest may be set at such a level that brings about persistent unemployment.

[4] In the same way, the empirical evidence seems to contradict the notion that higher wages would lead to substitution of cheaper factors of production for labor. The exemplary case is the well-know study of the fast food industry in New Jersey, which found a positive correlation between the minimum wage and employment (Card and Krueger, 1995).

[5] That GE models do not support the notion that the abundance of a factor of production will be associated with lower remuneration has been pointed out by a survey of those models (Bliss, 1975).

[6] The same is valid for Bowles and Gintis’ (1993, p. 84) notion that market exchanges are usually contested and endogenous enforcement costs are not zero, and, as a result, there are conflicts of interest among exchanging parties. Therefore, if enforcement costs were nonexistent the Arrow-Debreu results would prevail. It must be noted that all the literature on post-Walrasian economics presumes continuity between the classical political economy authors and the post-marginalist revolution economics, which would mean that there are no significant distinctions between Smith, Marx, Walras and Arrow.

[7] Colander et al. (2004), for example, seems to suggest that several of the post-Walrasian developments can be seen as breaking up with orthodoxy. For a critique see Vernengo (2010).

Additional Readings:

Bliss, Christopher (1975), Capital Theory and the Distribution of Income, Amsterdam and New York: Elsevier North-Holland.

Bowles, Samuel and Herbert Gintis (1993), ‘The revenge of homo economicus: Contested exchange and the revival of political economy’ The Journal of Economic Perspectives, 7(1), 83-102.

Card, David and Krueger, Alan (1995), Myth and Measurement: The New Economics of the Minimum Wage, Princeton: Princeton University Press.

Chirinko, Robert (1993), ‘Business fixed investment spending: Modeling strategies, empirical results, and policy implications’, Journal of Economic Literature, 31(4), 1875-1911.

Colander, David, Rick Holt, and J. Barkley Rosser Jr. (2004), “The changing face of mainstream economics,” Review of Political Economy, 16, pp. 485-99.

Felipe, Jesus and Franklin Fisher (2003), ‘Aggregation in production functions: what applied economists should know’, Metroeconomica, 54(2-3), 208-262.

Garegnani, Pierangelo (1976), ‘On a change in the notion of equilibrium in recent work on value: a comment on Samuelson’, in M. Brown, K. Sato and P. Zarembka (eds), Essays in Modern Capital Theory, Amsterdam: North-Holland.

Heim, John J. (2009), ‘Which Interest Rate Seems Most Related to Business Investment?’, American Society of Business and Behavioral Sciences E-Journal, 5(1), February.

Keynes, John M. (1936), The General Theory of Employment, Interest and Money, New York: Harcourt Brace.

Lucas, Robert (1988), 'On the Mechanics of Economic Development,' Journal of Monetary Economics 22 (1), pp. 3–42.

Marx, Karl (1867), Capital, NY: International Publishers.Capital, NY: International Publishers.

Milgate, Murray (1979), 'On the origin of the notion of ‘intertemporal equilibrium’,' Economica, 46(181), 1-10.Economica, 46(181), 1-10.

Petri, Fabio (2003), ‘A ‘Sraffian’ critique of general equilibrium theory, and the classical Keynesian alternative’, in F. Petri and F. Hahn (eds), General Equilbrium: Problems and Prospects, London and New York: Routledge, pp. 387-421.

Samuelson, Paul (1962), “Parable and Realism in Capital Theory: The Surrogate Production Function,” Review of Economic Studies, 29(3), pp. 193-206.

Samuelson, Paul (1966), ‘A summing up,’ Quarterly Journal of Economics, 80(4), 568-583.Quarterly Journal of Economics, 80(4), 568-583.

Vernengo, M. (2010), 'Conversation or Monologue? On Advising Heterodox Economists,' Journal of Post Keynesian Economics, 32(3), pp. 389-96.

Garegnani and the revival of the surplus approach

(1930-2011)

Last weekend Pierangelo Garegnani passed away in Rome. He was the main disciple of Piero Sraffa, and one of the most important heterodox critics of the mainstream marginalist (neoclassical) approach. A full account of his contributions to economics is well beyond what I can offer in this space, but here are a few highlights.

As early as 1961, while spending an academic year at MIT, he suggested during a presentation by Paul Samuelson that his results depended on the assumption that all sectors use the same capital-labor ratio. The final results of his critique were presented in Garegnani's paper "Heterogeneous Capital, the Production Function and the Theory of Distribution." His paper shows conclusively that the marginalist theory of value and distribution based on an aggregate production function is untenable. This of course builds on Sraffa's work in the Production of Commodities (PC). By 1966, in the famous Quarterly Journal of Economics (QJE) Symposium, Samuelson had admitted that the neoclassical parable was not defensible.

In his 1976 paper "On a Change in the Notion of Equilibrium in Recent Work on Value and Distribution" Garegnani argued that to avoid the problems associated with the aggregative marginalist model, the mainstream had switched to Arrow-Debreu (AD) General Equilibrium models, which did not use aggregative capital, but also did not assume a tendency to a uniform rate of profit, which implies that it can only be seen as a short run equilibrium. Further, Garegnani later argued that, beyond the problem of being stuck with a short run theory, the AD model was still open to the capital critique, since a notion of aggregate capital was still needed for the equilibration of savings and investment (see his 2003 paper "Savings, Investment and Capital in a System of General Intertemporal Equilibrium").

Garegnani was also the central author arguing that the recovery of the classical theory of value and distribution (and hence Marx) was not incompatible with the Principle of Effective Demand (PED), as developed by Keynes and Kalecki. His two papers in the Cambridge Journal of Economics show that a rejection of the marginalist notion that labor and capital markets tend to full employment depends on the rejection of the mainstream theory of value and distribution, and that Keynes' PED is fully consistent with the old and forgotten classical or surplus approach. He also actively contributed to the extension of the PED to the long run until the end of his life (e.g. his paper with Trezzini).

There are several other contributions, in particular his work on the interpretation of Ricardo and his debates with orthodox Marxists, which again follow in the steps of his teacher. His work is essential for those interested in the understanding of the functioning of capitalist economies, and the incapacity of the mainstream to provide a useful tool to analyze reality.

On General Equilibrium (GE)

Nice post (and rare, since this kind of topic is often not dealt with) on GE by Alejandro Nadal at TripleCrisis.  In my view, the problem is less that equilibrium per se does not exist, as Nadal seems to suggest, but the particular notion of equilibrium that has come dominate economics after Arrow-Debreu and the Capital Debates.  I highly recommend the paper by Fabio Petri (here) for those interested on the subject.