Some Democratic Party groups are renouncing their once-egalitarian idols, the renaissance genius Thomas Jefferson and the populist Andrew Jackson. Both presidents, some two centuries ago, owned slaves. Consequently, the two men have been suddenly deemed unworthy of further liberal reverence.

In Connecticut, for instance, the state Democratic Party has removed the two presidents’ names from an annual fundraiser previously known as the Jefferson-Jackson-Bailey Dinner.

There are lots of strange paradoxes in the current frenzied liberal dissection of past sins.

One, a historic figure must be near perfect in all dimensions of his or her complex life to now pass progressive muster. That Jefferson is responsible for helping to establish many of the cherished human rights now enshrined in American life apparently cannot offset the transgression of having owned slaves.

Two, today’s moral standards are always considered superior to those of the past. Ethical sense supposedly always improves with time.

However, would American society of 1915 have allowed a federally supported agency such as Planned Parenthood to cut apart aborted fetuses to sell infant body parts?

Ivy League enrollment figures suggest that some of these universities have capped the number of Asian students. Is this really much different than the effort to curtail Jewish enrollment at Ivy League schools in the 1920s?

Three, the sins of the past were hardly all committed by racist, sexist, conservative white men.

Under the new morality, should we not also condemn the Aztec king Montezuma as a Hitler-like war criminal? No society prior to the Nazi Third Reich had so carefully organized and institutionalized the machinery of mass death that each year executed tens of thousands of sacrificial human captives from conquered neighboring tribes. Perhaps San Diego State University should stop using the nickname “Aztecs” for its sports teams, given the fact that the Aztecs practiced slave-owning, human sacrifice and ritual cannibalism.

The Zulus are often portrayed as saintly indigenous people, brutally colonized by rapacious British imperialists. That’s not quite the whole story. Earlier in their pre-British history, the Zulus’ King Shaka adopted the sort of military imperialism and internal police state that would have made Josef Stalin proud. By the time of his death in 1828, Shaka’s army had killed more than 1 million Africans through systematic imperial conquest and mass executions.

Applying the morality of the present in crude political fashion to ferret out the supposed race, class and gender immorality of the past is a tricky thing. Picking saints and sinners can boomerang in unexpected ways.

Will Democrats now also damn America’s most openly racist president since the pre-Civil War era — the liberal saint Woodrow Wilson?

Wilson successfully led the U.S. in World War I, tried to organize a global League of Nations — and was an unapologetic Southern racist in word and deed. It was Wilson who fought the integration of the U.S. military and did his best as president of Princeton University to deny talented African-Americans admission.

Should Princeton focus only on that disreputable aspect of his legacy and thus change the name of its vaunted Woodrow Wilson School of Public and International Affairs?

Supreme Court Justice Earl Warren is worshipped as a progressive icon who through his work on the Supreme Court helped enshrine a liberal agenda. But no American was more responsible for incarcerating Japanese-Americans in internment camps. As California’s attorney general, Warren, in conjunction with liberal President Franklin Roosevelt, fanned racist paranoia and stripped constitutional rights from tens of thousands of U.S. citizens.

Should we therefore wipe away any mention of “The Warren Court” or Roosevelt’s New Deal? Or do history’s liberal sinners alone win special exemption from today’s liberal witch hunters?

Should we regard civil rights advocate Malcolm X as unworthy of attention, or instead as a complex historical persona?

By present ethical standards, was Malcolm more than just a convicted thief and avowed Communist who dismissed Martin Luther King Jr. as “chump,” declared that he was “glad” when John F. Kennedy was assassinated, and talked of black superiority as he condemned whites as “devils.”

The architect of Planned Parenthood was the feminist family planner Margaret Sanger. Shouldn’t Planned Parenthood denounce Sanger’s legacy, given her eugenics agenda that deliberately sought to focus abortions on minority communities?

The past is not simplistic “gotcha” melodrama in which we convict figures of history by tabulating their sins on today’s moral scorecards.

Instead, history is tragedy. It is complex. Moral assessments are dicey. With some humility, we must balance past and current ethical standards, as well as the elements of the good and the bad present in every life.

And we must avoid cheap, politicized moralizing that often tells us more about the ethics and ignorance of today’s grand inquisitors than the targets of their inquisitions.

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