Chris Bray, 39, is a Ph.D. candidate in history at UCLA and a former infantryman in the U.S. Army. In "When Washington Pleads Weakness" (page 18) Bray describes how private military forces have served as a kind of governmental id since the birth of the United States, operating outside the law but often on behalf of state interests. "For the first 100 years of the history of this country we had private armies attacking the neighbors," he says. "People are fascinated by this idea of a balanced and free republic that never entirely existed."

"The Framers never expected the president to be the living embodiment of our national hopes and dreams, the guy or gal who makes the world safe for democracy and cheers you up when you're blue," says Gene Healy, a senior editor at the libertarian Cato Institute. On page 20, reason excerpts his new book The Cult of the Presidency: America's Dangerous Devotion to Presidential Power (Cato). Healy, 37, says he initially set out to write "yet another Bush's-imperial-presidency book" but soon became fascinated by the longer history of the presidency. "Strange and wonderful as it is to contemplate during an election year," says Healy, the Founders thought "the president was mostly supposed to keep his mouth shut."

The San Francisco–based journalist Wagner James Au, 40, is the author of the new book The Making of Second Life: Notes from the New World (HarperCollins). In "Virtually Free" (page 62), he describes the rise and fall of free minds and free markets in the online world of Second Life, which he sees as a place where the science fiction visions of novelists like Neal Stephenson collide with the work of Robert Nozick, John Rawls, and other political philosophers interested in the idea of social contracts. Au's alter ego in Second Life is Hamlet Au, "a guy who looks like me but wears a white suit in tribute to Tom Wolfe." He blogs at New World Notes (