Conquest and rebellion are two violent ways of gaining control of the state. On the face of it, they are different than the method of forming a state presented in chapter 18.
Hobbes argues that there really isn’t a significant difference between a state whose origin is violent, which he calls the commonwealth by acquisition, and one whose origin is peaceful, which he calls the commonwealth by institution.
Hobbes’s discussion of liberty marks an interesting reversal of course for him. As the handout documents, in his first political work he had agreed with Aristotle that the subjects of democracies enjoy significantly more liberty than those who live in other kinds of states.
That claim is withdrawn in chapter 21. In its place, we are reminded of all the lousy things that democracies do to their subjects. Remember that according to the theory of sovereignty we read in chapter 19, all states claim the same powers, regardless of whether they are democracies, oligarchies, or monarchies. I think what we’re seeing in chapter 21 is the application of that theory.
The right of self-defense is inalienable, meaning it can’t be given up. This has several important implications for Hobbes.
Finally, there is the loosely related claim that subjects are released from their obligations to a sovereign when the sovereign can no longer provide protection. That was terribly important for establishing a political settlement after Charles I was defeated in the English Civil War.
It doesn’t sound like much. But for some of his contemporaries all this was enough to brand Leviathan as a “rebel’s catechism.”** See Curley’s Introduction, p. xxxviii.