Bucking Montesquieu and most other theorists of republicanism, Madison argued that the American system required a large rather than a small territory to operate effectively: “Extend the sphere, and you take in a greater variety of parties and interests; you make it less probable that a majority of the whole will have a common motive to invade the rights of other citizens; or if such a common motive exists, it will be more difficult to feel it . . . to act in unison with each other.”

A year before he articulated his “Doctrine,” Monroe offered a similar perspective in an address to Congress, though with a different rationale: “The greater the expansion, within practical limits, and it is not easy to say what are no so, the greater the advantage which the States individually will derive from it . . . . It must be obvious to all, that the further the expansion is carried, provided it be not beyond the just limit, the greater will be the freedom of action to both Governments, and the more perfect their security; and, in all other respects, the better the effect will be on the whole American people.”