At this point in the conversation, we're usually treated to a chorus of, "Hey, liberals say crazy things too!" And the answer to that is
The difference is that these left-wing lunatics do not have anywhere near the power or prominence of their right-wing counterparts. They're not hosting nationally syndicated talk shows. They're not parlaying famous last names into political careers. And they are sure as hell not running the Democratic Party, as the right-wing lunatics are clearly running the GOP.
Here's the thing, conservatives. We marginalize and trivialize our extremists. Maybe we shouldn't do that; sometimes the extremists have legitimate grievances. But it's better than what you do with yours. You celebrate and lionize them. It's not just Reagan; it's Limbaugh and Coulter and Savage and Hannity -- and yes, Boehner and Cantor and McConnell, and the current version of Romney (which may of course change next week, or an hour from now, but for now
So here's my challenge. If you are tired of liberals making hay of every crazy thing some conservative pundit or politician says, do something about it. Point and laugh at your own side's lunatics, as we do. Make us believe that common ground is possible, that you have the same ends for the country that we do even if we disagree about the means. Put your racists and fascists in the same room where we keep our communists and anarchists, and keep them decently out of public view.
Or if you're not willing to do this, understand that we have no choice but to consider you just as bad as the worst of your number, and act accordingly.