Background
The Permanent Income Hypothesis (PIH) is a key theory in the field of consumption economics. Formulated by renowned economist Milton Friedman, the hypothesis provides an insightful understanding of consumer behavior and spending patterns over time. It fundamentally alters how we perceive the link between income and consumption, thereby shaping many economic policies and models.
Historical Context
Milton Friedman introduced the Permanent Income Hypothesis in the mid-1950s as part of his critique of earlier Keynesian consumption theories. While Keynes suggested that current income primarily drives consumption, Friedman proposed a more dynamic model where individuals base their consumption on an assessment of their permanent income, which is a smoothed version of their actual or current income.
Since its introduction, the PIH has significantly influenced economic theories and practices, and it has parallels with other advanced consumption theories, such as Modigliani’s Life-Cycle Hypothesis.
Definitions and Concepts
The Permanent Income Hypothesis posits that:
- Permanent Income: The longest-term average income that individuals expect to earn over time.
- Transitory Income: Short-term fluctuations in income that are unexpected and not considered reflective of an individual’s longer-term earning potential or trends.
- According to PIH, consumption mainly responds to changes in permanent income rather than these short-term changes in transitory income.
Key Concept: The theory implies that consumption patterns will exhibit a more consistent trajectory even when income shows variability in the short-term.
Major Analytical Frameworks
Classical Economics
The PIH departs from Classical Economics, which often presumed that current income is the main determinant of spending.
Neoclassical Economics
The neoclassical school has integrated the Permanent Income Hypothesis into broader models of rational expectations and efficient markets, emphasizing the role of intertemporal decisions and lifetime utility maximization.
Keynesian Economics
Unlike Keynesian economics, which highlights the importance of current income levels in driving consumption, the PIH suggests that individuals smooth consumption based on their expectations of long-term income.
Marxian Economics
Marxian economics, with its focus on production and class struggle, does not directly integrate PIH but might juxtapose it with analyses of income inequality and consumption.
Institutional Economics
Institutionalists might critique the PIH for not fully accounting for historical and societal influences on income and consumption behavior.
Behavioral Economics
Behavioral economists scrutinize PIH by examining how real-world deviations in human behavior, irrational expectations, and psychological factors influence consumption choices.
Post-Keynesian Economics
Post-Keynesians argue that the PIH, while insightful, may oversimplify complex socio-economic dynamics, particularly how income distribution affects consumption.
Austrian Economics
Austrian economists focus on individual choices and could integrate PIH within broader themes of human action and temporal considerations in economic decision-making.
Development Economics
In the context of developing economies, PIH could guide policies aimed at long-term income stability to foster sustainable consumption patterns.
Monetarism
Monetarists, in alignment with Friedman, support PIH as it complements their focus on long-run forecasts and stable consumption trends.
Comparative Analysis
PIH contrasts with models premised on liquidity constraints and precautionary savings or those emphasizing the impact of psychological factors on consumption.
Case Studies
Empirical validations and criticisms can be derived from studying inconsistencies, such as:
- Aggregate Consumption Data: At times, macroeconomic data do not perfectly align with PIH predictions.
- Microeconomic Evidence: Household surveys often reveal consumption behavior patterns reflecting both permanent and transitory income influences.
Suggested Books for Further Studies
- A Theory of the Consumption Function by Milton Friedman
- Rational Expectations and Inflation by Thomas Sargent
- Handbook of Macroeconomics by John B. Taylor and Michael Woodford
Related Terms with Definitions
- Life-Cycle Hypothesis: A theory which suggests individual consumption is structured over their lifetime in response to predictable life stages and income changes.
- Rational Expectations: The notion that individuals make decisions based upon their rational outlook and predictions about the future.
- Permanent Income: Long-term average income expected by an individual, based on accumulated human capital and other persistent factors.
