What is the Object of the Constitutional Oath?

How and why are public officials today obliged to follow the Constitution? Article VI gives us a crystal-clear answer: They are bound "by oath or affirmation, to support this Constitution." But what is "this Constitution"? American constitutional culture today describes its Constitution in ways that presuppose that the Article VI oath binds officeholders to an external, objective, common object: the same commitment for all oath-takers today, and the same commitment today as in the past. Justices on the Supreme Court took their constitutional oaths at different times, spread out over 31 years from 1991 to 2022, but they claim to fulfill those nine oaths by speaking collectively of "the Constitution." Americans regularly describe their Constitution as the oldest, still-operational, written national Constitution in the world. These sorts of contingent practices could, of course, change. But until they do, we should understand oath-takers to be swearing to obey the same entity which has been operative since the eighteenth century. If we have a living Constitution today, it must have been living from the very start. Change in constitutional requirements may be justified only if rooted in the rules for constitutional change operative at the Founding. [ABSTRACT FROM AUTHOR]