If you've ever wondered what goes on inside the mind of a Rush Limbaugh fan, let us introduce you to Jim Derych. For more than a decade, Derych was a loyal, self-assured Limbaugh follower—a so-called dittohead—who uncritically accepted the ideas Rush advocated on his syndicated national radio program. But by the time George W. Bush took office in 2001, Derych found himself questioning the wisdom of Rush's ideology, ultimately concluding that Limbaugh's social, economic and political principles sounded better in theory than they worked in practice. In 2004, Derych deserted Limbaugh and the Republicans and switched his allegiance to the...