Everybody's business is nobody's business.

When a task is declared to belong to everyone, no particular person may feel obliged to take charge. Shared responsibility can therefore result in the task being neglected or left unfinished.

The saying warns that collective concern needs clear ownership. Assigning a named person or defined group to act makes it less likely that each participant will assume somebody else will deal with the matter.

Use it when an unassigned duty, public concern, or group task is being overlooked because responsibility is too widely dispersed. It can support a call to designate who will act, rather than merely asking everyone to care.