A hypothetical condition without government, used in social-contract theory as a baseline against which to judge political authority.
In more detail
For Hobbes, a condition without a coercive power would make basic security impossible. Locke held that the state of nature is governed by natural law but lacks a common judge with authority, and that it is preferable to subjection to arbitrary absolute power. Whether it is a historical claim or a thought experiment is disputed; most modern readers treat it as the latter.