Comparing the relative lack of condemnation for communist mass murderers (representing "the left" in this debate) as compared to Nazi mass murderers (representing "the right") , Glenn Reynolds says:

Indeed. Communism’s mass murders have gotten less condemnation precisely because academic Marxists and sympathetic journalists continue to cover for them.

The US and nearly all of Europe fought a long and horrible war against the Nazis. Tens of millions died. Dozens of countries were involved. And the good guys won! Even now, reminders of WWII are everywhere in the country - statues in parks, "war memorial" arenas, etc.. The conflict was the defining event of an entire generation, and many today refer to people from that era as The Greatest Generation. It was kindof a big deal for the US, and definitely a big deal for our European allies. And, likewise, the Nazis remain the greatest enemy we've ever gone to war with, both in terms of military power and the pure evil they brought to the world. They remain in our national consciousness as the horrible black evil that the Greatest Generation faced and defeated. Indeed the greatness of the Nazi's evil is a big part of what makes the generation that defeated them so great - defeating such an enemy requires greatness. Great and Good Us vs Evil and Horrible Them. And We Won! Right? The stories are still part of us. Likewise, "Nazi" remains a powerful insult because everybody understands exactly what they did.

On the other hand, we didn't go to war with Stalin or Mao - Stalin was our ally in WWII, after he'd already killed millions of people. When they killed their millions of victims, the news of their atrocities wasn't tied up with stories of our soldiers and allies bravely trying to defeat them. We simply weren't invested in the situations in the way we were invested in WWII. They killed their millions and we went about our business the same way we are going about our business while Darfur is being slaughtered. They are stories about other people, about things that happened to people in other countries. They weren't stories about the US. So a lot of people just don't know what happened in Russia in the 1930s or China in the 1960s (or in the Sudan, right now). We can all learn the facts about what happened, but Stalin's and Mao's slaughters will always remain things that happened to other people. And things that happen to other people just don't have the resonance of things that happen to us. In other words, we don't use Stalin and Mao as examples of mankind's evil the way we still use Hitler because Stalin and Mao aren't part of our cultural heritage the way Hitler is.

IMO.