“Third parties are like bees,” the intellectual historian Richard Hofstadter wrote in 1955. “Once they have stung, they die.” It’s an aphorism that aptly describes the anti-slavery and anti-immigrant parties of the mid-nineteenth century, the Populists and Progressives who ushered out the Gilded Age, as well as more recent third-party standard bearers, from George Wallace to Ross Perot. All of these movements and figures influenced American politics dramatically, before fading away and leaving the basic two-party duopoly intact. Of late, though, our potential third parties have been skipping the stinging part and going straight to the dying. This was true of Unity ’08, the much-ballyhooed attempt by former Democratic and Republican politicos to put up an independent alternative to Barack Obama and John McCain. Despite enjoying a wave of free publicity and boasting Sam Waterston of “Law & Order” as their spokesman, the Unityers never even came close to conjuring up a plausible candidate or platform, and their movement fizzled out amid attempts to entice an unwilling Michael Bloomberg into the lists.