Is it true that "for the most part the Constitution is irrelevant to the current political design of the nation"?
Here Lexington (for Klarman) talks about the administrative machinery of the government, but he might as well be talking of political parties, or the press, or interest groups, or the ways that the each of the Constitutional branches performs legislative, executive, and judicial tasks. That's true. Add it all up and the actual functioning of the American political system isn't easily recognizable from a literal reading of the Constitution. And yet...the reason that things work the way they do, with dispersed and multiplied power, and separated institutions sharing powers, and all the rest of it, is in my view fundamentally tied to Constitutional design. For example, the fact that the American bureaucracy is more political (in the sense of partisan and electoral politics) than bureaucracies in other democracies is a direct consequence of the mixed masters the Constitution gave the "executive" branch. So while plenty of our current institutional arrangements evolved over time, I would strong argue that the core political theory embedded in the Constitution is quite relevant to how they evolved, and the institutional arrangements detailed in that rulebook are quite relevant today.