Of Usurpation

Chapter 17 is brief because its argument follows directly from chapter 16. Conquest — the seizure of political authority by foreign force — creates no legitimate authority. Usurpation is the same thing domestically: the seizure of power to which one has no right within an existing political community. Locke defines it as the exercise of power which another has a right to. The usurper gets into the throne legitimately belonging to another; or the usurper exceeds the limits of the office they rightfully hold.

The key point is that the mode of acquiring power does not change what power is. Legitimate authority in a commonwealth is defined by the designation of who holds it — through inheritance, election, or whatever process the constitution prescribes — and by the limits within which it is to be exercised. A usurper, having acquired power by force or fraud rather than by legitimate process, has only the appearance of authority. The community owes no obedience to a usurper as such; it may obey in order to preserve the peace, but its obedience creates no right in the usurper and terminates the moment a legitimate claimant can restore the rightful order.

The distinction between usurpation and tyranny that Locke will draw in chapter 18 is important: usurpation involves the right sort of power exercised by the wrong person; tyranny involves any person exercising power beyond their right. Both are illegitimate, but for different reasons and with different implications. Locke's taxonomy of illegitimate authority — despotism, conquest, usurpation, tyranny — is designed to make clear that there is no path to legitimate political power other than the consent of the governed, properly understood.