Where does moral hazard collide?

The change in behaviour that follows once a loss is insured: the insured take on more risk, or exert less care to prevent a loss, because they no longer bear its full cost. Arrow's 1963 Uncertainty and the Welfare Economics of Medical Care brought the idea into economics, noting that insurance against a cost weakens the incentive to avoid that cost. Pauly's 1968 comment sharpened it, showing that the care a person forgoes, or the extra services they use, is a rational response to a lower price at the point of use rather than any lapse of morals. This is the origin of the term and the referent the rest of the map is measured against. The behaviour is what matters here: a real, observable shift in what people do once the cost is shared.[1][2]

Unit

An insured party's care or risk-taking, once covered

Recovery means

Not applicable

Measured by

Compared as claims, care, or risk-taking with and without coverage

Moral hazard as hidden action inside a formal principal-agent model: an agent takes an action the principal cannot observe, so the contract must tie pay to whatever outcomes or signals are visible. Holmstrom's 1979 Moral Hazard and Observability proved the informativeness principle, that any signal carrying information about the agent's effort belongs in the optimal contract, however noisy it is. The problem is now a matter of designing incentives under unobservable effort, and it is solved as an optimisation rather than described as a behaviour. This framing, recognised in the 2016 Nobel award, is where the meaning drifts furthest from its insurance origin. What began as a person taking less care becomes an agent whose action is a hidden variable to be inferred from signals.[3]

Unit

A principal's contract with an agent whose effort is unseen

Recovery means

Not applicable

Measured by

Modelled as an optimal incentive contract written on observable signals of effort

Moral hazard in banking: a bank, or its depositors and creditors, take on more risk because a public backstop absorbs the downside. Deposit insurance, a lender of last resort, or an expectation of rescue for a bank too large to fail all shift part of the loss from the risk-taker to the guarantor, which weakens the incentive to be cautious. Kareken and Wallace's 1978 Deposit Insurance and Bank Regulation showed that flat-rate deposit insurance, priced without regard to a bank's portfolio, lets a bank raise its risk at the guarantor's expense, so insurance without matching regulation invites the very behaviour it was meant to cushion. The mechanism is the insurance meaning applied to a firm rather than a person, with the state as insurer. It carries the same core idea, that shielding someone from a cost changes what they do.[4]

Unit

A bank's risk-taking under deposit insurance or bailout expectations

Recovery means

Not applicable

Measured by

Studied as risk-taking that rises with the coverage of a public guarantee

Moral hazard in health insurance: the extra medical care an insured patient uses because coverage lowers the price they pay at the point of use. In the standard account this extra use is a welfare loss, care that is worth less to the patient than it costs to provide. Nyman's 1999 The economics of moral hazard revisited challenged that reading, arguing that much of the extra care is bought with an income transfer from the healthy to the sick that insurance is meant to provide, so a large share of it is a welfare gain rather than a loss. This is the same observable behaviour as the insurance origin, more care once the price falls, read through a different welfare lens. The field shows that even where the meaning is stable, what it implies for policy is contested.[5]

Unit

An insured patient's use of care at a reduced out-of-pocket price

Recovery means

Not applicable

Measured by

Estimated as the extra care used when coverage lowers the price at the point of use