Category Archives: Paul Samuelson

Some Logical Fallacies in Economics

Economic theory of various kinds are often employed to formulate policies in the real world. Often, certain conclusions of a particular economic theory are utilised in policy making. For instance, some of the insights/conclusions arising from mainstream economics are: fiscal deficits are inefficient and inflationary; a perfectly competitive economy is desirable because it is efficient; increase in money supply causes inflation and increase in investment (domestic and foreign) will create employment. Hence, we are regularly advised to lower fiscal deficits, encourage ‘efficiency’, etc.

Broadly, two kinds of logical fallacies are committed by economists and policy makers. Firstly, there are logical fallacies in the domain of economic theory. Secondly, a logical fallacy is committed when real-world policy decisions are derivatives of conclusions from a particular economic theory. This blog post makes use of Stephen F Barker’s book The Elements of Logic (1965) to illustrate some of the logical fallacies in economics.

According to Barker, a “fallacy is a logical mistake in reasoning.” He identifies three broad categories of logical fallacies: (1) non sequitur, (2) petition principia and (3) inconsistency. Fallacies of non sequitur (Latin: “it does not follow”) occur when there is an insufficient link between premises and conclusion. “If the premises are related to the conclusion in such an intimate way that the speaker and his hearers could not have less reason to doubt the premises than they have to doubt the conclusion, then the argument is worthless as a proof, even though the link between premises and conclusion may have the most cast-iron rigor,” logical fallacy of petition principia (Latin: “begging the question”) occurs. Lastly, fallacies of inconsistency occur “when someone reasons from a set of premises that necessarily could not all be true.”

Logical fallacies in economic theory

An economic theory like any scientific theory begins from a set of premises. These premises can be based on observation, fact, other theories, (reasonable) assumptions, etc. Obviously, these premises have to be sufficiently general for it to be a ‘theory.’ From these premises, through the process of (deductive) reasoning, we arrive at certain conclusions. Note that unrealistic assumptions do not render an economic theory fallacious. However, their utility in real-world policy making is contingent on how ‘approximate’ the assumptions are to the particular context.

Hence, given the premises, if the conclusions do not follow, the economic theory under consideration is said to be logically fallacious. This, in fact, happened to the marginalist theory of value and distribution. In the 1960s, it was demonstrated bySraffaGaregnani and others that marginalist theory of value and distribution is logically fallacious. This was shown so clearly that defenders of the theory, notably, Paul Samuelson, admitted this defect. The main reason for this logical fallacy was/is that prices (value) and distribution are interdependent and hence are simultaneously determined. Therefore, the distribution theory in neoclassical economics (marginal productivity theory) cannot be logically prior and independent of the theory of prices (value). In other words, capital cannot be treated as a distinct factor of production, independent of prices. This is because, at an aggregate level, capital is comprehensible only as a value magnitude. Therefore, the construct of the aggregate production function breaks down and with it the whole neoclassical edifice of value and distribution crumbles. In any case, to circumvent such logical critiques, the concept of inter-temporal equilibrium was constructed. So far, it seems to have been ‘successful’ in warding off capital-theoretic critiques. But, this shift towards inter-temporal equilibrium from long period equilibrium has seriously compromised the relevance of such economic theory. For, ‘anything goes’ in temporary equilibrium. The capital theoretic fallacy is of the non sequitur type as there is an insufficient link between the premises and conclusion.

Marginalist economics studies human behaviour. It is a science of choice thanks to Lionel Robbins who presented a clear definition of neoclassical economics (which originated in the works of Jevons, Walras and Menger in 1870s). Hence, the theory assumes scarcity of both factors and commodities. The central problem in economics becomes that of – allocation. The theory starts with specifying endowments to agents and concludes  that there is full employment of resources. After all, if the issue is that of allocation, there will necessarily be a full-employment of resources both before and after the process of allocation (carried out by the market forces of demand and supply). In this case, the premises and the conclusion are connected in such an intimate manner that it seems to commit the fallacy of petition principia.

Consumers maximize utility. Producers maximize profits. This gives us equilibrium. However, is there a clear line of demarcation between a producer and a consumer? What if an agent is both a consumer and a producer? In the language of set theory, what if the intersection between consumers and producers in an economy is not a null set? If so, is it logically consistent to have a strict demarcation between producers and consumers?

Logical fallacies in economic policy

Economists, policy makers and journalists argue for a particular economic policy based on certain premises. These premises are nothing but an admixture of various economic theories. Note the emphasis on ‘theories’, for there is not just one economic theory but multiple economic theories. Most of them are competing paradigms, i.e., they ask similar questions but provide dissimilar answers. Examples include Austrian economics, Marxian economics, Classical economics and Keynesian economics. The dominant paradigm, of course, is the marginalist one; variants of this include New Classical Macroeconomics, Monetarism, New Keynesian Macroeconomics, Microeconomics, etc.

The question we are interested in asking is: what is the basis on which a particular economic policy is favoured. A few examples are provided below.


Premise: Increase in money supply causes inflation.

Conclusion: Therefore, increase interest rates to reduce inflation.


Premise: Inflation is determined by inflation expectations.

Conclusion: Therefore, the Central Bank should target inflation expectations.


Premise: Given full-employment of all resources, an increase in expenditure will raise prices.

Conclusion: Fiscal deficits are inflationary. Therefore, reduce fiscal deficits.

The premise in the first example is from a Monetarist paradigm; the premise in the second one is a New Keynesian perspective and the premise in the third example is a typical neoclassical/marginalist view. Are these kinds of policy conclusions logically correct? Do the conclusions follow from the premises? Or, are we taking a leap of faith? For, the economies which the premises talk about and describe aretheoretical worlds which (hopefully) have certain characteristics of the real-world. In any case, hasty conclusions should not be made. This is especially important for policy making in an economy like India which is very distinct from the theoretical worlds mentioned above.

Yet another commonly used argument is to favour a policy based on its success in another economy. For a long time, India followed economic doctrines which were promoted in the advanced economies of the West. Today, we see a similar trend where examples and case-studies from ‘other emerging economies’ are used to argue for a particular policy recommendation in India. But, India is structurally – socially, culturally, politically and economically different from these other economies. Hence, we again take a leap of faith. I end with such a claim which was made to argue that FDI is favourable: “in Indonesia 10 years after allowing 100 per cent FDI, 90 per cent of the retail sector is controlled by the small shopkeepers.”

Pierangelo Garegnani (1930 – 2011)

On October 14, 2011, heterodox economics (in particular, classical economics) lost one of its warriors. This post attempts to summarise some of his key contributions towards economic theory. First and foremost, he was an economic theorist par excellence. He contributed to the famous (now, almost forgotten) capital theory debates in 1960s along with Piero Sraffa and Joan Robinson on his side and Paul Samuelson and Robert Solow on the other. Alongside others, he pointed out logical flaws in the marginalist conception of capital and its devastating effects on equilibrium. Basically, marginalist theory of value and distribution (in modern parlance, microeconomic theory) was shown to be logically inconsistent. Today, these debates hardly ever appear in economics textbooks because marginalist or neoclassical economics invented inter-temporal equilibrium to take care of capital-theoretic issues. Moreover, history of economic thought has been sidelined – through famous graduate economic programs and by preaching that history of economic thought is of no use to a “practical” economist, both in academia and in business.

Garegnani made significant contributions to the revival of classical economics on the foundations laid down by Piero Sraffa. In particular, Garegnani, through various journal articles (in Italian and English) resurrected the works of old classical economists – mainly Smith, Ricardo and Marx. More than Sraffa, perhaps, it is Garegnani who has aided the revival and resurrection of classical economics. His command over the history of economic thought with a special focus on old classical economists and ‘old’ and ‘new’ neoclassical economists (Walras, Wicksell, Hicks, etc) is evident from his clear exposition of their analytical structure.

Like ‘old’ classical economists, Garegnani’s interest has been to explain growth dynamics of an economy. This, he believed and also demonstrated that it is possible by drawing insights from Keynes and working on a classical (Sraffian) foundation. In this regard, Garegnani and his friends-colleagues-students have been quite successful in their analysis of capacity utilization, supermultiplier, role of wages, profits being a monetary phenomenon and so on.

Given the massive contributions made by Garegnani, it has been an honour for me to have been introduced to his work during my Masters in Economics at University of Hyderabad. It is one of the few Universities, in India and possibly, in the world, which still teaches classical economics as a distinct approach to understanding contemporary economies. I hope that more Universities begin to recognise the benefits of a pluralist education and start teaching classical economics as a distinct subject.


Robert Vienneau  Susan Pashkoff  Francesco Saraceno  Tyler Cowen  David Ruccio  Matias Vernengo

Paul Samuelson: The Father of 'Modern Economics' Dies

All those who have studied economics for the past 50 years or so have heard about Samuelson – Foundations of Economic Analysis, Samuelson-Stopler theorem, Factor-price equalisation theorem, revealed preference theory, Bergson-Samuelson social welfare functions, non-substitution theorem, linear programming in economics, etc. The first one is his 1947 book which dominates economics teaching even today, directly or indirectly. Samuelson transformed economics into some sort of science (pseudo-science, as some call it)-social physics. [For more on this, go here]

Robert Lucas on Samuelson:

“Samuelson was the Julia Child of economics, somehow teaching you the basics and giving you the feeling of becoming an insider in a complex culture all at the same time. I loved the Foundations. Like so many others in my cohort, I internalized its view that if I couldn’t formulate a problem in economic theory mathematically, I didn’t know what I was doing. I came to the position that mathematical analysis is not one of many ways of doing economic theory: It is the only way. Economic theory is mathematical analysis. Everything else is just pictures and talk.” [Marginal Revolution and here]


In his Foundations, he is supposed to have popularised the views of Keynes. In fact, what he popularised is the neo-classical synthesis (IS-LM curves, which were created by Hicks). Hence, what we learn in most macroeconomics texts is not what Keynes said. Post-Keynesian economics is more closer to what Keynes said.

Despite his ‘ideas of good economics’, one needs to appreciate the works he carried out in different areas in economics – macroeconomics, public finance, international trade, consumer theory, capital theory and general equilibrium, etc.

In his initial editions of the Foundations, one could find a few pages devoted to the 1960 capital theory debates. However, with passage of time, the debate was relegated to footnotes. Now, in mainstream textbooks, capital theory is entirely omitted. In fact, Samuelson admitted the problems neoclassical microeconomics and general equilibrium run into because of their notion of capital. [More here]

I end with two questions.
Is mathematics the only way of studying economics and analysing economies? [We mostly use calculus and game theory. Should we employ other kinds of mathematics?]

How reliable are textbooks? It makes learning easy, but probably, a bit too easy.