Sociology Plus
Consumption Function Definition
The consumption function describes the relationship between an individual’s expenditure on consumption and their level of income. It posits that, all else being equal, consumption tends to increase in proportion to income, although this relationship is not necessarily instantaneous. For this correlation to hold, several external conditions must be met, including price stability, the rate at which durable goods are replaced, the availability of credit, and the general level of inflation, all of which influence decisions regarding when and how much to consume. Furthermore, the proportion of income allocated to saving also increases as income rises, reflecting that poorer populations have fewer resources available for saving or investment.
Macroeconomic Origins
This concept was central to the macro-economic theories developed by J. M. Keynes, who focused on the interplay between expenditure on consumption and saving (and subsequent capital investment) within fluctuations of capitalist economic growth.
Theoretical Modifications
Subsequent economic thought has modified the original Keynesian account through alternative hypotheses concerning how income affects spending:
- Permanent Income Hypothesis: This view suggests that the relationship between consumption and income is more accurately measured against permanent, long-run levels of income rather than fluctuating year-to-year variations. This hypothesis is associated with Milton Friedman.
- Life-Cycle Hypothesis: This alternative maintains that an individual’s age influences their spending patterns; specifically, younger and older consumers tend to allocate a larger share of their income to consumption while saving less, compared to those in middle age.
Sociological Relevance
While these accounts are crucial for estimating aggregate expenditure levels and the savings ratio—indicators important for national macro-level economic management—they possess limited relevance when attempting to understand the deeper social and cultural dimensions that shape individual consumption behaviour.