What Gives Locke's Social Contract Its Air of Unreality, of Toothlessness, Is That It Is a Reversion to the Old Thomist Idea of Revocability without the Retention of Armed Force in Civil Society

Here lies the crux of the difference between the old Thomist and the new Hobbesian contract; the first deals with a society that has kept its arms, the second with one that has 'chosen' to disarm itself. In the first, resistance to the prince who transgresses natural law takes the form of resort to force or the threat of it. In the second, resistance is unnecessary, but would be impossible if it were necessary. In Rousseau's intellectually weaker, in some ways decadent, quasi-Hegelian version of the irrevocable social contract, resistance to the general will would be tantamount to resisting one's own will, properly understood (the condition of proper understanding being the tautological one that one's own will conforms to the general will). What gives Locke's social contract its air of unreality, of toothlessness, and of placebo, is that it is a reversion to the old Thomist idea of revocability without the retention of armed force in civil society which would make performance by the contracting parties mutually contingent, and resistance to unlawful government meaningful.

--Anthony de Jasay, Social Contract, Free Ride: A Study of the Public Goods Problem (Oxford: Clarendon Press, 1989), 72-73.