Information Economics: Reasoning Under Asymmetry and Uncertainty¶
Classical economics assumed everyone knows everything - prices, quality, intentions. Reality is different. Buyers don't know product quality. Employers don't know worker effort. Insurers don't know who will file claims. This asymmetry isn't a footnote; it's the main story.
Information economics emerged from taking this seriously. The tools that resulted - adverse selection, moral hazard, signaling, screening - turn out to be reasoning primitives that apply far beyond markets. Anytime one party knows something another doesn't, these patterns emerge. Job interviews, romantic relationships, diplomatic negotiations, and medical diagnosis all involve the same structures.
The extraction principle: these tools work because they describe information geometries, not economic assumptions. Adverse selection occurs whenever private information exists before a transaction. Moral hazard occurs whenever actions are hidden. Signaling occurs whenever costly actions can reveal type. The patterns are general; economics merely formalized them.
What makes these tools powerful is that they're diagnostic. When you see a market unraveling, check for adverse selection. When you see behavior change after a contract, check for moral hazard. When you see costly, seemingly wasteful actions, check if they're signals. The tools tell you where to look.
Information Asymmetry¶
Reasoning Under Uncertainty¶
- Risk vs Uncertainty
- Option Value
- Expected Value vs Expected Utility
- Bayesian Updating
- Price as Information
- Winner's Curse
Quick Reference¶
Decision Type -> Tool¶
| You're asking... | Start with... |
|---|---|
| Why does this market fail? | Adverse Selection or Moral Hazard |
| What does this costly action reveal? | Signaling |
| How do I extract information? | Screening |
| Why isn't delegation working? | Principal-Agent |
| How should I design the rules? | Mechanism Design |
| Can I quantify this uncertainty? | Risk vs Uncertainty |
| What's flexibility worth? | Option Value |
| How do I value risky outcomes? | Expected Utility |
| How should I update beliefs? | Bayesian Updating |
| What does this price tell me? | Price as Information |
| Why do I keep overpaying? | Winner's Curse |
Reading Path¶
Foundations (start here):
- Akerlof, Spence, Stiglitz Nobel lectures (all accessible)
- Dixit and Nalebuff, "Thinking Strategically"
Going deeper:
- Milgrom and Roberts, "Economics, Organization and Management"
- Knight, "Risk, Uncertainty, and Profit"
Advanced:
- Roth, "Who Gets What and Why"
- Myerson's mechanism design papers
Usage Notes¶
These tools work best when information asymmetry is the central feature. Not every market problem is an information problem.
Domain of applicability: Strong where information is costly, private, or asymmetrically distributed. Weaker where information is cheap and public, or where non-informational factors dominate.
Limitations: Information economics can over-explain. Not every market failure is adverse selection. Not every insurance problem is moral hazard. These are hypotheses to test, not conclusions to assume.
Composition: Adverse selection and signaling/screening are solutions to each other - signaling resolves adverse selection. Moral hazard and mechanism design connect - design mechanisms to mitigate hidden action. Bayesian updating and screening combine - screens provide information that gets incorporated via updating.
Integration: Information tools complement core economics (they explain why simple market models fail) and behavioral economics (boundedly rational agents handle information differently than optimal Bayesians).