01/11/2011 08:48 pm ET | Updated May 25, 2011

Who's Illegitimate? The Presidents. Who Says?

If mental disturbance is, as it seems (and as I discussed in my last post), at the root of the shootings in Tucson, that leaves another question: what's at the root of all the rancor about political rancor?

Sure, some of it is outrage that outrage on the other side may have a political motive. But, let's be grownups: what do politicians, and their acolytes, ever say on any subject that doesn't have some political motive? There is something deeper going on now, some undercurrent that's more turbulent than the normal jungle-ball ethos of American politics. It's been with us now for almost two decades, and there's no sign that it's going away.

When Bill Clinton was elected in 1992, he won a large electoral vote victory but just a popular vote plurality thanks, in large part, to a third candidate in the race, Ross Perot. And thus began an attack on Clinton's presidency, ranging from murder rumors to impeachment, that was based on this fact: his opponents could never quite allow themselves to believe he was legitimately elected.

Anybody who lived through the Nixon or Reagan years, or the Carter years, for that matter, had seen furious opposition, founded in many cases in deep loathing of the occupant of the White House. But it never occurred to those opponents to suggest that Nixon, Reagan or Carter were anything but the legitimately elected president of the United States.

Flash forward to the 2000 election. Florida. Bush v. Gore. A conviction by Democrats that George W. Bush was not really, legitimately the elected president. He'd lost the popular vote. The Florida recount had been lawyered up and judged over. The war was bad, the post-9/11 behavior was often atrocious, but before any of that had occurred, a lot of Bush's opponents were convinced in their bones that he was illegitimate. That, as much as the Democrats' favored accusation -- our opponent is dumb (hello, "chimpy") -- flavored the anti-Bush world view for eight years.

And now, President Obama. Clearly elected, clearly legitimate, except for -- well, it started with birtherism, the insistence that he wasn't really born here. Other observers have linked that persistent charge to fear of The Other (first black president, after all). But there have followed all sorts of Manchurian-candidate fantasies, all based on the notion that we, the people didn't put this man in office. Illegitimacy -- not in the "bastard" sense, but in the sense that an electorate normally, however grudgingly, grants legitimacy to the product of the system -- has become the new currency of presidential opposition.

Its popularity, as a review of this little history will suggest, is not in its effectiveness: both Clinton and Bush won second terms. But it is a psychological Rubicon. Once it's crossed, an entirely different landscape of vituperation makes itself known. That's where we live now. A call for civility in a world where each party now feels the deep wound of having had its successful candidates delegitimized is likely to be as successful as ordering a Manischewitz spritzer in a Beirut bar.