Two Fundamental Objections to Marginalist Economics

In the past, several posts on this blog have raised dissatisfactions and have expressed discontent with the prevalent orthodoxy in economics – neoclassical economics (more accurately, marginalist economics). This post is similar in intent as the previous posts, but it chooses to focus on, what I deem to be, the two most theoretically and empirically inadequate tenets of marginalist economics: (1) the marginal productivity theory of (income) distribution and (2) the supply-side growth theory.

Equilibrium prices and quantities of commodities and factors of production (such as labour and ‘capital’) are determined simultaneously in marginalist economics. Distribution is endogenously determined according to the relative scarcity of factors, i.e., based on the demand and supply of factors. Under conditions of perfect competition, in equilibrium, the wage rate equals the marginal product of labour and the profit rate equals the marginal product of ‘capital’. That is, there is no surplus in the marginalist theory of value and distribution. The origin of the marginal principle is to be found in Ricardo’s discussion of intensive rents. This principle has been illegitimately extended to labour and to ‘capital’. In marginalist production theory, labour is freely substitutable with ‘capital’. The famous Cobb-Douglas production function is based on the substitutability of the two factors of production. The use of the aggregate production function has been shown to be logically unsound (due to problems of not just measurement but also aggregation of ‘capital’) and therefore its applicability in empirical analysis is severely undermined. But, this logical critique, famously known as the Cambridge Capital Controversies, remains ignored.

Underlying the supply-side theory of growth is the marginal productivity theory of distribution. Relative scarcities of the factors induce changes in their prices such that the demand for factors equals their supply. This implies that, in equilibrium, all factors are employed. The real wages are assumed to be sufficiently sensitive to disequilibrium in the labour market such that they adjust in order to render the labour demand equal to its supply. And, the aggregate production function states that a growth in the factors will lead to a growth in output. In other words, if the labour and ‘capital’ endowments are increased, there will be higher growth. Aggregate demand adapts to aggregate supply and the possibility of an aggregate demand deficiency is ruled out. Slight modifications have been made to this theory in order to explain the presence of unemployment. These modifications take the form of rigidities of the real wage, which cause labour unemployment. In marginalist theory, one of the explanations for the presence of unemployment is labour market rigidities. If these rigidities are absent, labour will tend to be fully employed. Such theories have come under severe criticism and rightly so.

To conclude, marginalist economics is unsatisfactory on logical grounds. Moreover, it does not perceive the possibility of an aggregate demand deficiency. Lastly, unemployment is seen to be a consequence of imperfections or rigidities and not as permanent feature of competitive economies.

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