If there is any “ambiguity” about Stalin’s moral record, it may be because communism strikes a chord with some of our nobler impulses, seeking equality for all and an end to poverty. No such universal aspiration can be found in Nazism, which, even on its face, was not concerned about what was good for all, but about what was good for one supposed racial group, and which was clearly motivated by hatred and contempt for other ethnic groups.
But communism under Stalin was the opposite of egalitarian, for it gave absolute power to a few, and denied all rights to the many. Those who defend Stalin’s reputation credit him with lifting millions out of poverty; but millions could have been lifted out of poverty without murdering and incarcerating millions more.
Making conversation during a road trip recently, my dad asked me why Hitler was seen as more of a symbol of absolute evil than comparable people like Stalin. It's a pop-culture thought experiment, of course, not a serious historical question up for objective analysis. You either share the vague impression behind the premise or you don't. As for me, I do — I think there's clearly still a large remnant of revolutionary chic among the young and stupid (to say nothing of the cynical and stupid in academia), and I'm certain that a mainstream webzine for progressive airheads like Salon would never run a gushing interview with a celebrity charlatan-intellectual who even hinted at an affinity for Nazi leaders, let alone boasted of one. Anyway, anecdotal observations aside, my answer was that, one, Hitler lost, and it's true what they say about the authors of history books. Had he won and presided over a relatively stable German empire across Eurasia, maybe we'd have a more nuanced view of him. After all, in the early part of the 20th century, race-based pseudoscience and Social Darwinism were hardly the exclusive property of the political right; many prominent progressives were also supporters of eugenics. And Hitler was famously inspired by the eugenics movement in the U.S. (as well as the thoroughness with which it wiped out its indigenous population). If you want to be slightly cynical about it, you could say that condemning Nazism as irredeemably, indisputably rotten from the start due to its racial obsession is probably a way of coping with our own cultural guilt via projection.
Secondly, I said, riffing off of Isaiah Berlin, ever since the Enlightenment, there's been a strong belief among progressive intellectuals that human society can be comprehended and controlled by means of the same sort of scientific rationality that made such stunning advances in taming the natural world. Surely there must be a Newton of social science who can formulate the simple, clear laws by which we can reorder society and put an end to injustice and unfairness! As you can easily enough find, a significant number of people still go through incredible contortions to make Marx fit the bill, but aside from those true believers, everyone else is still waiting in vain for such a savior. There seems to be a stubborn reluctance to accept that a theory that looks so good on paper could keep going wrong when implemented in reality. Many intellectuals still harbor a No True Scotsman-like belief that maybe just maybe if we gave it one more try, we could somehow fix the bug — not a feature, damn it! — the bug that, from the Jacobins to the DPRK, keeps producing similar results.
The comments to the article are pretty much as expected; one eyebrow-raising bit is Singer replying to a comment wondering why he didn't include Mao in this comparison by saying that most of Mao's victims were killed by his "egotistical and economic lunacy" rather than a deliberate campaign of annihilation. I have to admit that's a fine distinction I wouldn't have made myself; perhaps Mao is simply history's worst manslaughterer, then? At any rate, there's also the usual counter-charges that colonialism and capitalism are just as bloody-handed and therefore unfit to judge. Possibly so, but again, the Enlightenment-derived ideologies were supposed to be the moral, humane improvement upon the status quo, so forgive me for not being impressed by a measly tu quoque defense. I can resignedly accept the reasoning that liberal democracies, whatever their histories, are the best we can do in an imperfect world; I'm much more disturbed by the lingering faith in radical ideology, the willingness of so many to be impressed by empty rhetoric, to believe that this time, utopia is surely just up ahead, right around the next mountain of corpses.
Of course, this is all just a parlor game. Powerful people are all dangerous, rotten bastards, regardless of the motivations and rationalizations. I think we can agree on that much.