Powell (The Moral Tradition of American Constitutionalism: A Theological Interpretation) argues that the American system is largely a product of Enlightenment liberalism, embodying many of the features of the ideal Enlightened polities constructed by Locke, Montesquieu and others. He recognizes the importance of civic republicanism, Protestantism, and other factors, but places his accent on the Enlightenment heritage, especially in the clear public/private distinction.
That Americans had their own version of Enlightenment, though, is evident in the Founder’s “unwillingness to trust the legislature’s exercise of reason” (62). Jefferson opposed Virginian’s plan to concentrate power in the legislature, arguing that “173 despots would surely be as oppressive as one.” He had no confidence in lawmakers: “as they would be the sole judges of the good or evil, it would be also a power to do whatever evil they please.”
Whatever happened to the power of reasoned deliberation to arrive at the truth? Jefferson sounds like nothing so much as a secular Calvinist preacher.