This is so good I'll have to just quote him at length. The motivation is Paul Ryan and Glenn Beck repeating the standard line on the progressive movement that you hear from pretty much everyone right of center (conservative, libertarian, populist, you name it) these days.
"This progressives-as-un-American-transformers narrative is almost
completely nonsense. The original progressives were almost entirely
concerned with rehabilitating the American Founders’ ideals in a new
political and economic era. For example, Woodrow Wilson revered
Alexander Hamilton for his “deep and passionate love of liberty, and
that steadfast purpose in the maintenance of it.” He argued that no one
but Hamilton “could have done the great work of organization by which he
established the national credit, and with the national credit the
national government itself.” Wilson is hardly alone. Progressive
intellectual John Dewey recognized and celebrated the permanently Jeffersonian core of the American political tradition. For Jefferson, Dewey wrote, “it was the ends of democracy, the rights of man—not of men in the plural—which are unchangeable.”
Dewey’s progressivism consisted in the next sentence: “It was not
the forms and mechanisms through which inherent moral claims are
realized that are to persist without change.” And that, by the way, is
the small kernel of truth at the core of Ryan’s and Will’s attacks on
progressivism old and new. Most progressives believed in the profound
importance of the Founding’s ideals, but they realized that some of the Constitution’s rules were being used to perjure those very ideals. The ends
of democracy are the key. Always have been. The specific means—can we
elect our senators? Can presidents run for office interminably?—are
considerably less important. Of course, that’s what most Americans (especially women and non-white citizens) believe, if you ask them about the details.
(Dewey and Wilson are hardly the only examples of early progressives
who loved the American tradition. Other than Charles Beard and a few
other minor figures, almost everyone was on board with the line of
argument that I’ve just sketched. Even Herbert Croly, in a strange way.)
Conservatives (then and now) will have none of this. They see
progressivism as an attempt to transform and abandon the Founding’s
principles (or a project aimed at “detaching people from the
Constitution,” etc). For these folks, real Americans
venerate the original Constitution in every aspect. They believe that
America means limited government along precisely the original lines.
Just don’t ask them anything about women’s suffrage or the direct
election of senators or the “Three-Fifths Clause,” etc (usually)."