Why Defense Is Hard to Sell One Person at a Time
Many goods can be withheld from someone who does not pay: a shop can refuse a sale, and a utility can disconnect a customer. National defense does not work that way. If a country deters an attack or protects its territory, the resulting security generally extends to people inside it, whether or not each person contributed directly.
Economists call this a public good: a benefit that is difficult to restrict to paying customers. Defense is not perfectly uniform—people and places may face different risks—but a government cannot readily shield only the taxpayers who funded a particular defense measure.
The Free-Rider Problem
That creates a free-rider problem. Each person may prefer that others bear the cost while they enjoy the protection. If everyone acted on that incentive, voluntary contributions could fall short of what it takes to provide defense, even though many people value it.
Governments generally address the problem by financing defense collectively, chiefly through taxes rather than a separate voluntary purchase by each resident. That shifts the question from “Will this person pay for protection?” to “How should the shared cost be raised and allocated?” The tradeoff is that collective funding can provide a service private sellers struggle to supply, but decisions about its scale and cost become matters of public policy.
