The nature and purpose of the think tank is questioned in this week's headlines—but what is the origin of this strange beast?

Writing in National Affairs, Tevi Troy provides a potted but thorough history of the think tank. First seen early in the twentieth century, the institutions believed in the power of the technocratic model, and were "propelled by the metaphor of social afflictions as maladies and public-policy experts as the physicians who could heal the patient"—Brookings is the prime example here. But when it came to the afflictions of the market, Brookings' propensity toward economic intervention was later challenged by the American Enterprise Institute, which put down roots in Washington at the close of World War II.

Despite varying ideological leanings, Troy contends that until the 1980s, both left- and right-of-center think tanks retained the character of "universities without students," dedicated to cool analysis rather than heated partisan activism. But during the Reagan administration, with the rise of the Heritage Foundation, what Troy calls the "advocacy think tank" or "do tank" again pioneered a new model.

In the 1990s, centrist Democrats copied the Heritage model with the Progressive Policy Institute, which became home to a Clinton shadow cabinet in waiting. By 2001, even left-of-center wonks found that retreating to the ivory tower was no longer an option: "Academia was no longer a comfortable place for policy-minded individuals."

The third generation of think tanks nearly scrapped the wonks altogether, spending nearly as much on media outreach as policy scholars. The Center for American Progress (CAP) is the archetype of this new superactivist tank. And if Troy were updating his article today, he might want to note the February launch of the Washington Free Beacon, a right-wing clone of CAP's ThinkProgress newsroom.

There is little mention of the few think tanks not easily placed on the partisan spectrum—and none of the libertarian Cato Institute, an omission Troy no doubt regrets given the recent public spat over its future governance. Troy's effort is nonetheless notable for its thorough but accessible analysis of the DC institutions most committed to serious thought—but too often unreflective about themselves.