orthodox theory of irrevocable social contract than for those who see the attractions of opting out. Locke, for example, maintains that individuals are not obliged to depart from the state of nature and enter a civil order, but that once one has brought his person and property into political society, he may never then withdraw them. Why not? I cannot see that Locke provides any substantive argument for that conclusion. It is question-begging to maintain that the contractors have undertaken a perpetual obligation. Perpetuity is a very long time, and risk-averse persons will be loath to tie themselves down to that extent, especially if they enjoy some prescience concerning the inefficiencies and moral obtuseness that states regularly display. They might very well instead build into the original compact a requirement of periodic reaffirmation. But who knows? 
That is to return to the previous section's examination of the uncertainty of the social contract's terms. It also leads into the next section's examination of consent and future generations. 
D. Transgenerational consent Contract would have value as a descriptive theory if there were reasons to believe that states come into the world on the back of consent. Alas, such reasons are scant. Contract has value as a prescriptive theory of political obligation if those who have consented (or are deemed to have consented) are held to account as a result of their free assent. That, though, is not the normative significance attributed to contract by the canonical liberal theorists. Rather, primordial assent is invoked to justify ascription of duties to citizens here and now. It is unclear how this is supposed to work. A fixed point of our moral conceptions is that people can bind themselves via their own free acts, but cannot so bind unrelated others.9 Allegiances sworn long ago or far away do not travel well. 
Locke is acutely aware of this problem and turns to a consent that is ongoing and tacit to ground political duties. An extensive literature, much of it highly critical, addresses this aspect of the Lockean theory. Tacit consent as it presents itself in the Second Treatise bears an uncomfortably close resemblance to Hobbes's coerced consent. If the only alternative to obedience one has is to flee the sovereign's domain, thereby forfeiting property and valued personal associations, the alleged voluntariness of acquiescence is dubious. There may be ample reasons to comply with governors' commands, but these will be reasons of self-interest under duress.10 Sometimes, though, one might be able to avoid the reach of the rulers. To get away with evading onerous demands is not the same as faithlessness to a freely assumed loyalty. So-called tacit consent should be understood as the midwife of tacit resistance, not of political duty. A plausible alternative is that there exists a general moral duty to obey lawful political authorities, but that would render contract theory redundant. 
Autonomy is the privilege of every generation. "The earth belongs in usufruct to the living," Thomas Jefferson famously wrote to James Madison in a letter dated September 6, 1789, going on to declare, "Every constitution, then, and every law, naturally expires at the end of nineteen years. If it be enforced longer, it is an act of force and not of right." Practicality was not Jefferson's greatest strength, and as a piece of constructive political engineering, the nineteen-year sunset provision can seem bizarre. (Madison seems to have so regarded it.) No less bizarre, however, is an assumption that ancestral acts of agreement are transmitted through the national DNA to generation after generation of citizens. If consent is even in the ballpark as an answer to the question of how political obligation is incurred, then it must be one's own consent that does the work. Jefferson is simply working out the implications of that moral datum for the new American experiment. Now that th