Everyone in a shared garden can enjoy the vegetables, but only a few people regularly water and weed. The contributors may begin to wonder why they should continue carrying the work if the benefits are available regardless.

That is the free-rider problem: some shared benefits are difficult to restrict to contributors. If enough people withhold effort, the resource or activity can deteriorate even when everyone would prefer it to continue.

An absence does not explain itself

Someone may be taking advantage, but they may also lack time, have a disability, or contribute in ways that others do not see. A group needs to understand the pattern before treating every unequal contribution as misconduct.

Sanctions change the incentives as well as the relationship between participants. In public-goods experiments, some people paid to sanction low contributors, and the availability of punishment changed cooperation. In a community, applying such a response also requires deciding which contributions are possible and which absences have been misunderstood.

Groups can make responsibilities visible through a responsibility matrix, offer different ways to contribute, and decide which benefits should remain available regardless of contribution. These choices involve values as well as incentives. A mutual-aid group may deliberately support people who currently cannot reciprocate; that is part of its purpose, not automatically a failure of cooperation.

Real cases