A good explanation of the Clinton-Trump clash we are living through, and of Trump’s having taken the Republican Party by storm, is in Eric Posner and Adrian Vermeule’s 2010 brief for executive supremacy as the way we do constitutionalism. The Posner-Vermeule thesis in The Executive Unbound is that the Madisonian philosophy of separation of powers as a constraint on the presidency no longer exists, and good riddance. The more authoritative check on executive power, they say, is majority opinion and the fact that the President must face the voters every four years. This, and not Greg Weiner’s paean to Jemmy Madison, is the only source we have now for safe, effective, and informally limited government. Those wanting Madison on demand, Posner and Vermeule inform us, are whistling past the graveyard of a constitutionalism that no longer fits this American nation.