Joseph Stiglitz: When Information Is Imperfect

How Joseph Stiglitz showed that imperfect information makes markets fail in many ways, and why he became a prominent critic of the IMF and globalisation policies.

Joseph Stiglitz shared the 2001 Nobel prize with George Akerlof and Michael Spence for their work on markets with asymmetric information, where one side knows more than the other.

Imperfect information everywhere

Stiglitz showed that information problems are not rare exceptions but are everywhere, and they can make markets work very differently from textbook models.

Screening

In insurance, companies don’t know who is high-risk. Stiglitz and Michael Rothschild showed in 1976 how insurers design different contracts, such as policies with different deductibles, to make customers reveal their risk type. This is called screening.

Credit rationing

In 1981, Stiglitz and Andrew Weiss explained why banks may refuse to lend to some borrowers even if they’re willing to pay higher interest rates. Higher rates can attract riskier borrowers and encourage riskier projects, so banks limit lending instead of raising rates. This helps explain why small businesses and poor people struggle to get credit.

Efficiency wages

With Carl Shapiro, Stiglitz showed in 1984 that firms may pay above-market wages to discourage shirking, helping explain unemployment.

Public roles

He chaired the US Council of Economic Advisers under President Clinton.
He was chief economist of the World Bank from 1997 to 2000.

Critic of globalisation policies

In Globalization and Its Discontents (2002), Stiglitz criticised the IMF’s handling of the Asian financial crisis and transition in Russia. He argued that rapid capital market liberalisation and austerity harmed developing countries. His critique was controversial, but it influenced debates on capital controls and development policy.

Inequality

Later, Stiglitz wrote extensively on inequality, arguing that high inequality harms growth and democracy.

The small business loan

A small shop owner offers to pay a high interest rate for a loan. The bank refuses, worried that anyone willing to pay so much may be taking big risks. Stiglitz's theory explains why credit can be scarce even for willing borrowers.

Thinking markets always clear when prices adjust

Imperfect information can lead to rationing and unemployment even when prices can move.

Key takeaways

Stiglitz shared the 2001 Nobel for work on asymmetric information.
He explained screening in insurance and credit rationing by banks.
He co-developed the efficiency wage theory of unemployment.
He became a leading critic of IMF policies and inequality.