Game Theory · GT-25
Once you're insured against a risk, your own behavior toward that risk quietly changes — and the insurer bears the cost of that change.
A change in behavior that occurs after a contract is signed, when one party is insulated from the consequences of their own actions and the other party can't fully observe or verify that behavior. Unlike adverse selection (hidden information before the contract), moral hazard concerns hidden actions taken after the contract begins.
The term originated in 17th-century insurance industry usage, but its formal economic analysis dates to Kenneth Arrow's foundational 1963 paper on the economics of medical care and uncertainty.
The Mechanism
Risk-taking behavior shifts once the downside is covered
The behavior shift happens after the contract, not before — this is the defining feature that separates moral hazard from adverse selection. The insurer can't fully observe the change, which is exactly why it's a genuine economic problem rather than a simple pricing question.
01 · THE TIMING DISTINCTION FROM ADVERSE SELECTION IS THE WHOLE POINT
Hidden action, not hidden information
Moral hazard is specifically about behavior that changes as a result of reduced accountability after risk has been transferred — a driver with comprehensive insurance might drive marginally less cautiously, not because they lied about anything upfront, but because the incentive structure itself shifted once they were covered.
02 · IT APPLIES FAR BEYOND INSURANCE
Any principal-agent relationship with imperfect monitoring
Moral hazard shows up anywhere one party's effort or care can't be perfectly monitored by the party bearing the consequences — employees whose compensation isn't tied to outcomes, executives managing shareholder capital, government bailout recipients who take on excessive risk knowing a rescue is likely (a dynamic widely discussed after the 2008 financial crisis) — the mechanism is identical across all these settings.
03 · THE STANDARD FIXES ARE DEDUCTIBLES, CO-PAYS, AND MONITORING
Skin in the game restores the incentive
Real institutions address moral hazard by ensuring the insulated party still bears some meaningful cost of bad outcomes — deductibles, co-insurance, performance-based pay, and monitoring/auditing all work by partially restoring the link between the covered party's own choices and their own consequences.
Where It Fails / Inversion
Where it fails / inversion
Over-correcting for moral hazard by imposing excessive deductibles, co-pays, or monitoring can undermine the entire point of the original insurance or delegation arrangement — a health insurance plan with deductibles so high that people avoid necessary preventive care, or a manager so tightly monitored that all initiative is stifled, trades one inefficiency (moral hazard) for another (under-utilization or demotivation) that can be just as costly.
How To Use It
Worked example · deposit insurance and bank risk-taking
Federal deposit insurance protects depositors, but it can also create moral hazard for banks — knowing depositors are protected regardless, a bank's management may be tempted toward riskier lending than they would pursue if depositors' direct scrutiny (and potential withdrawal) still disciplined their choices. This is precisely why deposit insurance is paired with capital requirements and regulatory examination — mechanisms designed specifically to substitute for the market discipline that insurance itself removed.
How to use it
Whenever you're designing an arrangement that insulates someone from the downside of their own decisions — an insurance policy, an incentive plan, a delegated authority — explicitly ask what behavior change that insulation will predictably cause, and build in a partial cost-sharing or monitoring mechanism before the behavior shift becomes expensive, rather than reacting to it after the fact.
See Also