In economics, “having rational expectations” means that individuals and businesses use all available information, including their past experiences and knowledge of how the economy works, to make informed and unbiased predictions about the future.
It doesn’t mean they’re always right, but it does mean their mistakes are random and not systematic.
The theory contrasts with the idea of adaptive expectations, where people only base their predictions on past trends.
Key Principles of Rational Expectations
The theory is built on the following core ideas:
- Rationality: Economic agents are assumed to be rational and will act in their own self-interest to maximize their utility or profit.
- Use of Information: Individuals use all available and relevant information to form their expectations. This includes public information, their personal experiences, and an understanding of government policies.
- No Systematic Errors: Errors in expectations are random and not predictable. For example, people won’t consistently overestimate or underestimate inflation. If a systematic error exists, rational individuals would learn from it and adjust their expectations to correct it.
Rational Expectations vs. Adaptive Expectations
Rational expectations emerged as a critique of adaptive expectations. Here’s a quick comparison:
- Adaptive Expectations: This backward-looking model assumes people base their expectations solely on past events. For instance, if inflation was 3% last year, people would expect it to be 3% this year. The problem is that this model creates predictable errors. If inflation is accelerating, people will consistently underestimate it.
- Rational Expectations: This forward-looking model assumes people are smarter than that. They won’t just look at last year’s inflation. They’ll also consider things like the central bank’s announced policies, changes in fiscal policy, and other relevant economic news to form their expectations. This makes their errors unpredictable, as the only errors are due to unforeseen events or “shocks” to the system.
How It Influences Economic Policy?
The theory of rational expectations has significant implications, especially for government economic objectives and policies. The Lucas critique, a major contribution to this theory, argued that traditional economic models failed because they didn’t account for how people’s expectations would change in response to a new policy.
For example, a government might try to stimulate the economy by increasing the money supply to lower unemployment. Under adaptive expectations, this might work temporarily. However, with rational expectations, people would anticipate the policy’s inflationary effects, immediately demand higher wages, and push prices up, nullifying the policy’s intended effect on employment.
This suggests that only unexpected policies can have real, short-term impacts on the economy.