The contemporary Tea Party Movement, like its revolutionary ancestor, looks to principles for guidance. Yet an old but active fault line runs just beneath the surface of the movement that has the potential to cause a fatal rupture. Tea Partiers simultaneously promote both a conservatism based upon the principles of the American founding and a libertarianism based on individualism, but the two are ultimately incompatible.

Libertarians are good at explaining why the market works and why government fails, and they have made important policy initiatives in areas such as school choice. On the other hand, they actively oppose laws prohibiting obscenity, protecting unborn children, promoting marriage, limiting immigration, and securing American citizens against terrorists. These positions flow from core principles that have more in common with modern liberalism than with the American founding, and which threaten to erode our constitutional order even further.

The attraction of libertarianism is also its main defect: it offers neat solutions to complex problems. Unfortunately, reality is far more complex than libertarians acknowledge. Only conservatism offers principles adequate to that reality. Consider ten claims libertarians often make:

1. “The Founders of the American political order were libertarian.” Although the American Founders believed in limited government, they were not libertarian. The Constitution was designed for a federal system of government, specifying and limiting national powers and leaving to the states the exercise of their customary powers to protect the health, safety, morals, and welfare of their citizens. None of the American founders challenged these customary state powers, nor did they attempt to repeal them. Even on its own terms, the Constitution provides for powers that many libertarians would object to, such as establishing post offices, granting patents, regulating commerce among the states, and suspending the writ of habeas corpus.

2. “Conservatism fears new ideas because it has no distinctive principles of its own to oppose them.” This claim, made by F.A. Hayek, is simply false as applied to American conservatism (as Hayek himself knew). American conservatism seeks to conserve the principles of justice that lie at the root of the American political order, what might be called Natural Law Liberalism. These principles, enunciated in the Declaration of Independence, are rooted in nature, which fixes the boundaries to all authority. They include “the Laws of Nature and Nature’s God”; “self-evident” truths such as “all men are Created equal” and “are endowed by their Creator with certain unalienable Rights”; and a clear statement of the end of government, to “secure” rights and to “effect [the] Safety and Happiness” of the governed.

3. “Only individuals exist, therefore there is no such thing as a ‘common good.’” The statement reflects the corrosive nominalism that Richard Weaver decried inIdeas Have Consequences, and which fatally undercuts the principled limits to coercive authority identified above. Every human association, whether a marriage, business partnership, or sports team, has a common good, or why would it exist?

Common goods are not substantial entities standing over and against individual persons; they are the good of individual persons. But this does not mean common goods are always divisible into individual shares, like a cake. An orchestra, a marriage, an army cannot be divided without being destroyed. Within such associations individual persons exist as bandmates, spouses, and soldiers.

The common good of the political association consists in the ensemble of conditions in which persons and associations can more easily flourish. These are nicely summarized in the Preamble to the Constitution of the United States: “to . . . establish justice, insure domestic tranquility, provide for the common defense, promote the general welfare, and secure the blessings of liberty to ourselves and our posterity.”

4. “The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others.” The “harm principle,” first formulated by J.S. Mill, is a moral claim. It cannot be derived from moral skepticism without committing a self-referential fallacy: The argument, “We don’t know what is right or wrong, therefore it is wrong to do x,” is obviously invalid.