The difference between these two kinds of liberalism — constitutionalism grounded in humility about human nature and progressivism grounded in utopian expectations — is a crucial fault line of our politics, and has divided the friends of liberty since at least the French Revolution. It speaks to two kinds of views about just what liberal politics is.I don't think he has quite cracked the code on conservative liberalism in the progressive era. I do not think Theodore Roosevelt was utopian--he was trying to find better forms. It just so happened that the forms for restraining the excesses of an imperfect humanity matched, for a short while, the designs of utopians like Woodrow Wilson who sought the perfect system.
One view, which has always been the less common one, holds that liberal institutions were the product of countless generations of political and cultural evolution in the West, which by the time of the Enlightenment, and especially in Britain, had begun to arrive at political forms that pointed toward some timeless principles in which our common life must be grounded, that accounted for the complexities of society, and that allowed for a workable balance between freedom and effective government given the constraints of human nature. Liberalism, in this view, involves the preservation and gradual improvement of those forms because they allow us both to grasp the proper principles of politics and to govern ourselves well.
The other, and more common, view argues that liberal institutions were the result of a discovery of new political principles in the Enlightenment — principles that pointed toward new ideals and institutions, and toward an ideal society. Liberalism, in this view, is the pursuit of that ideal society. Thus one view understands liberalism as an accomplishment to be preserved and enhanced, while another sees it as a discovery that points beyond the existing arrangements of society. One holds that the prudent forms of liberal institutions are what matter most, while the other holds that the utopian goals of liberal politics are paramount. One is conservative while the other is progressive.
In any event, read the whole thing.