There is a problem in the way the study of American political development (APD) is currently bifurcated between the 'cultural' approach and the 'institutional' approach. The cultural approach tries to explain change in terms of historical forces such as race, economics, liberalism, the founding, and so on. The institutional approach, on the other hand, tries to explain change logically, in terms of the history of the operational procedures of institutions such as political parties. The trouble is that these two approaches cannot integrate each other's findings, and they maintain -- internally -- differing and opposing schools of thought about what exactly drives the evolution of America's politics. My way of making sense out of this chaos is very straightforward: I argue that at the root of all of America's political development is a radical philosophical movement called the Enlightenment. In chapters one and two I show how there are four specific types of early Enlightenment thinking at work in America's founding. I argue that these 'types' are exemplified by the ideas of Francis Bacon, Charles Montesquieu, Thomas Hobbes, and Jean-Jacque Rousseau. I go on to show how three of America's founding thinkers adapted these streams of thought and ended up forming the core principles of America's political culture. I demonstrate that these philosophers were Thomas Jefferson, Alexander Hamilton, and James Madison. I show how this theory addresses some of the basic problems within the cultural APD literature. These problems include the way in which cultural scholars think that American politics is most essentially about the conflict between egalitarian and libertarian values. What I do is give a richer and more accurate picture of the deep complexity of American liberalism: I demonstrate how America's three most influential philosophers intermingled four very different visions of liberalism, thereby setting America on a multifaceted, tortured, and convoluted developmental path. In chapters three and four I show how such philosophic differences and tensions play themselves out institutionally. I argue that the evolution of America's presidential regimes is formed and guided by these tensions. In particular I show how institutional change is generated not merely by the conflict that is set in place when new systemic paradigms try to overcome old ones, as is commonly believed, but also that -- first and foremost -- these conflicts are the result of the melding of the incongruous elements of Jefferson's, Hamilton's, and Madison's very different versions of liberalism.