Originalism as contract theory
Agoraphilia suggests viewing the Constitution as a contract.
There's much to that, altho Randy Barnett has pointed out it's not quite contractual. It binds me, even tho in 1789 my mother's ancestors were in Italy and Austria, and for all I know my father's ancestors objected to it (and in either event, I wasn't alive yet). Barnett finds the basis for originalism in a variant of the view. What, he asks, makes a law morally binding? (As opposed to practically binding -- the consideration that those in power will punish you for not heeding it). His answer is that the law was made pursuant to a system created by our ancestors, and the implied agreement is that if those temporarily in power heed the Constitution, we will heed the laws made pursuant to it. If they could say the Constitution has evolved to let them do what they please, then we could say that, morally, there is no duty to obey the laws they create.