Insurance requires the recognition that individually unpredictable events are collectively predictable, and the institutions to act on that took centuries to develop.
The early forms
Maritime arrangements spreading the loss of a ship among merchants existed in ancient trade.
Which were contractual arrangements rather than an industry, and they addressed a specific and obvious risk.
Bottomry loans, repayable only if the voyage succeeded, functioned as insurance embedded in finance.
The mathematical foundation
Probability theory developed in the seventeenth century, initially in response to questions about games of chance.
Which provided the tools to price risk rather than guess at it.
Mortality tables, compiled from parish records, allowed life expectancy to be estimated statistically for the first time.
That combination made life insurance possible on a sound basis rather than as a wager.
The coffee house
Marine insurance in London was arranged in a specific coffee house where shipping information was available.
Which developed into a market where individuals accepted portions of risks, writing their names under the terms.
The term underwriter derives from that practice.
Fire
Large urban fires prompted fire insurance, with insurers maintaining their own fire brigades.
Which produced the arrangement where brigades attended only buildings displaying their company's mark.
Municipal fire services subsequently replaced this, which is a clear case of a service moving from private to public provision for obvious reasons.
Mutual and proprietary forms
Mutuals owned by policyholders, and companies owned by shareholders.
Which have different incentives — a mutual returns surplus to members, a company to shareholders.
Many mutuals converted to company form in the late twentieth century, distributing accumulated reserves to members.
Regulation
Solvency requirements ensuring insurers can meet claims.
Which followed failures leaving policyholders without cover, and it requires capital held against liabilities calculated actuarially.
Compensation schemes covering policyholders if an insurer fails exist in many jurisdictions.
Social insurance
State schemes covering unemployment, sickness, injury and old age developed from the late nineteenth century.
Which applied the same pooling principle compulsorily and universally.
The distinction between contributory and tax-funded provision, and what follows from it, remains a live political question.
What insurance cannot cover
Risks that are certain, that are not independent between policyholders, or that the insured controls.
Which is why correlated risks like flooding in a defined area are difficult to insure commercially.
State backstops for such risks exist in several countries as a result.
Actuarial science
The discipline of calculating risk and reserving for future liabilities.
Which developed alongside life insurance and became a regulated profession with qualification requirements.
Actuarial judgement determines reserves, pricing and solvency assessment, which makes it central to whether insurers can pay.
Reinsurance
Insurance for insurers, spreading concentrated risk further.
Which allows insurers to write policies larger than they could bear alone and to cover catastrophe exposure.
Reinsurance markets cycle — capacity contracts after major losses and pricing hardens, then capital returns.
Moral hazard and adverse selection
Insurance changes behaviour, and those most likely to claim are most likely to buy.
Which are the two structural problems every insurance arrangement addresses.
Excesses, exclusions, underwriting and compulsory participation are the mechanisms used against them.
Climate and insurability
Rising losses from extreme weather have made some risks difficult to insure commercially.
Which has produced withdrawal from certain markets and rising premiums in exposed areas.
State-backed schemes for uninsurable risks exist in several countries and are under pressure.
Underinsurance
Where sums insured are below actual value, average clauses reduce claim payments proportionally.
Which means a partial loss on an underinsured property is settled partially.
Reviewing sums insured periodically is the practical response and is rarely done.
Claims and disputes
Refusals cluster around non-disclosure, exclusions, conditions and definitions.
Which are all visible in the policy before anything happens.
Ombudsman schemes provide free dispute resolution in many jurisdictions and overturn a meaningful proportion of decisions.
Data and pricing
Telematics, connected devices and broader data sources allow pricing on observed rather than assumed risk.
Which improves accuracy and raises questions about privacy and about which characteristics may lawfully be used.
Restrictions on using certain characteristics exist in several jurisdictions and constrain the data that can be applied.
Compulsory insurance
Motor insurance, employer liability and professional indemnity are compulsory in many jurisdictions.
Which exists because the harm falls on third parties who would otherwise be uncompensated.
It also creates a market where insurers can price risk and thereby create incentives for safety.
Life insurance and mortality
Pricing depends on mortality assumptions, and improving longevity has meant historical assumptions proved conservative for life insurance and costly for annuities.
Which is why the same demographic change helps one product and harms the other.
Discrimination and pricing
Restrictions on using certain characteristics in pricing exist in several jurisdictions.
Which improves fairness on the restricted characteristic and reduces pricing accuracy, and proxy variables remain a documented concern.