The system of constitutional government, especially as seen at its best among a people of democratic traditions and habits of mind, is a system of subjection to the will of the social organism, as expressed in an impersonal law. The difference between the system of status and the “constitutional system” [is that] subjection is not to the person of the public functionary, but to the powers vested in him. This has, of course, something of the ring of latter- day popular rhetoric, but it is after all felt to be true, not only speculatively, but in some measure also in practice.

It is a truism of American political science that presidential power is curbed power, power circumscribed by law. The Constitution's blend of rival institutions was meant to impede ambition on all sides. The point was to cripple absolutist temptations. In effect, the American framers assumed barbaric motivations and tried to insure their restraint. The resulting political system exemplifies, at least formally, a design for legislative dominance mitigated by executive discretion. Foreign and national security domains are not excepted; the president's hand may be stronger in foreign affairs, but it is limited there too. Institutional constraints arise not only from Congress's control of budgets and the Senate's role in treaty making and appointments but also from the many competitive agencies of the national security state, including intense jealousies among the military services, not to mention impediments imposed by the ever- changing dynamic of international relations. As Richard Neustadt's famous formulation had it, presidential power is the power to persuade, not command. Recent scholarship suggests that perhaps Neustadt overstated the case. George Edwards argues that even the most effective presidential persuader cannot easily reshape boundaries of the politically possible, or produce desired change when the political system resists it. The most capable presidents, he observes, “are leaders who depend on their environments for providing opportunities that they can exploit to accomplish their objectives.” Donald Trump's political environment offered unusually rich opportunities, but it has crashed against his boldest ambitions. By the same token, especially in many of his foreign policy moves—abandoning the Iran nuclear bargain and Paris climate accords, pressing tariffs on old friends and radically shifting gears on North Korea—Trump has shattered and reformed political relationships, broken constraints and perhaps created new ones. The relation between barbarism and democracy can be testy and impetuous.