There are many different types of liberal, though -- most conservatives in the United States are in fact liberals in the classic sense of that term. What distinguishes conservatism -- particularly in its Burkean form -- from modern liberalism and libertarianism is that conservatism has preserved the idea of ordered liberty, an idea that was central to classical liberalism as it existed in the 18th and 19th centuries. Both modern liberalism/progressivism and libertarianism reject the idea of ordered liberty, preferring ideology to custom and license to the notion of freedom under law. Thus, the authority of the State to legislate in the areas of morality is denied by both modern liberalism and libertarianism.
Where the two ideologies part company, however, regards economic liberty. As Powell points out,
Early liberals were generally enthusiastic supporters of markets and private property. (Adam Smith, for example.) But today most philosophical liberals—i.e., the people who apply the term to themselves as it’s understood within political philosophy—take a rather dim view of capitalism the related, robust right to private property. While they remain respectful of markets as an unmatched means for wealth creation, they believe those markets should be heavily regulated and their participants heavily taxed in order to minimize income disparities in the name of egalitarianism and social justice.Modern liberals embrace the power of the State over the economy while denying the power of the State over moral behavior. Libertarians deny the power of the State over both. But at their core, as Powell demonstrates in his essay, both liberalism and libertarianism share the same fundamental aversion to the idea of traditional order. Both are essentially two expressions of the same basic movement away from ordered liberty and towards and ideological embrace of a revolt against the power of the State.
Powell's analysis is interesting and insightful for the most part, but one point where Powell is wrong, involves his claim that libertarianism is itself a form of classical liberalism. While on a superficial level it may so appear, upon deeper inspection the differences between libertarianism and classical liberalism are apparent -- and it becomes plain that conservatism, oddly enough, ends up being far truer to the original vision of liberalism that motivated the American Founders and such conservative statesmen as Edmund Burke. Both classical liberalism and conservatism understand the need for ordered liberty, for a regime of virtue and responsibility undergirded by the rule of law and the enforcement of social norms that make limited government and individual rights possible to begin with. Ironically enough, while modern liberalism and libertarianism both claim the mantle of classical liberalism, it is the conservative tradition -- the tradition of Burke and Kirk and Weaver and Nisbet -- in which classical liberalism's fundamental insight remains alive. While libertarians and modern liberals are two sides of the same ideological coin in rejecting customary order, the classical liberal tradition of ordered liberty remains alive and well -- within conservatism.
As Russell Kirk once observed about Edmund Burke, "he was a conservative because he was a liberal."