The Marginalization of Absolute and Relative Income Hypotheses of Consumption and the Role of Fiscal Policy

In Keynes’ consumption theory absolute income is the major determinant of consumption, and the marginal propensity to consume determines the magnitudes of fiscal multipliers. Keynes employed a largely psychological analysis of consumption, rejecting the model of utility maximizing consumer. J. Duesenberry extended and improved Keynes’ approach by also emphasizing the role of psychological and social factors on consumption decisions (the relative income hypothesis). Similar conclusions regarding the role of income on consumption, and therefore support for Keynesian policies, are reached by Duesenberry’s analysis. The life-cycle hypothesis by Modigliani and Brumberg (1954), and the permanent income hypothesis by Friedman (1957), emerged as the two main alternatives to Keynes’ and Duesenberry’s approaches. Modern orthodox consumption theories are extensions of these two theories in a rational expectations framework. By employing the concept of forward looking, optimizing agents, current or relative income plays a minimal role in the life-cycle and permanent income hypotheses, and an even lesser role in contemporary orthodox consumption theories. Consequently, fiscal policy has a negligible effect on output and employment. The paper argues that Keynes and Duesenberry’s approaches were marginalized not because of their empirical or theoretical shortcomings, but because of emphasizing the psychological and social influences on consumption patterns, and because of not employing the intertemporal utility maximizing framework. The clear implication of the discussion is that the marginalization of absolute and relative income hypotheses was due to the dominance of a specific methodological framework that did not favour such approaches.