On this page recently, Alyssa Rosenberg warned us that genuinely reducing the "yawning" racial and sex divides between Americans will be "staggeringly difficult" ("America can't go forward until we escape our past," Dec. 26).

I concur that the most significant developments of 2017 were the banishing of Confederate monuments all over the country and the simultaneous banishing of so many powerful sex abusers. We were cleaning house. But Rosenberg's pessimism ignores how much we have to celebrate.

To begin with, we should acknowledge the brave, nearly unprecedented mission we are on to create a truly multicultural and gender-neutral society. As we strive to root out racial and sexual oppression, let's give ourselves credit for the willingness to dig into some of the most deeply entrenched human instincts.

All of our capacities for cooperation, respect and mutual regard were evolved in the small kinship bands our ancestors lived in for hundreds of thousands of years. Expanding those attitudes across racial differences is an ambitious leap.

And almost 150 years ago, Charles Darwin pointed out that the difference in body size between male and female mammals — sexual dimorphism — is correlated with polygyny. When males fight over access to females, the larger individuals tend to prevail, gaining access to more females and reproducing more prolifically. Thus, the male gender gets bigger.

While we are not gorillas, with males twice the size of females, the substantial size difference between men and women suggests a long genetic history of powerful men controlling access to multiple women. Of the hundreds of societies studied by anthropologists, 85 percent have permitted polygyny. Testing of the diversity in DNA is now confirming that for millennia, some men had many descendants and others had none.

Rosenberg's second omission is to ignore just how far, despite these entrenched obstacles, we have come in a short time. Virginia law actually outlawed interracial marriage until 1967.

Confederate statues convey unspoken messages of racial intimidation through the figures of dead military commanders. But just remember how recently we heard spoken messages of intimidation from living commanders. Theodore Roosevelt said that nine times out of 10 the only good Indians are the dead Indians. Woodrow Wilson praised the Ku Klux Klan. Franklin Roosevelt approved the imprisonment of 100,000 Japanese-Americans. Winston Churchill favored using poison gas on "uncivilized" tribesmen.

Our standards for acceptable sexual behavior are now changing dramatically, too. Certainly the way the legal system has treated rape has changed markedly. Until the late 1970s, a rape victim's sexual history was generally admissible evidence, and marital rape was not even a crime in every state until 1993.

My biggest concern about the way last year's wave of banishments of sexual abusers proceeded is their speed — which seemed to be coming at the expense of proportionality and due process. A crude joke or grope in public is not the same thing as a rape behind closed doors.

But I have come to terms with my qualms. Some entrenched behavior can be swept aside only by a pent-up tide of moral outrage. And such a flood cannot always part for the proprieties of proportionality and due process. After the hundreds of years of oppression suffered by African-Americans and women, the moral tide is a sweeping one indeed.

Rights are always violated in revolutions. We accept restrictions such as curfews and martial law during natural disasters and civil unrest. Abraham Lincoln suspended habeas corpus — due process for prisoners — because of the exigencies of the Civil War.

To be clear, though, in any society committed to the rule of law, a suspension of rights must be not only adequately justified, it must also be temporary.

So let us celebrate 2017. Government administrations come and go; morality is more enduring. In other times, we have seen entrenched behavior successfully transformed by moral values. Throughout our history, things such as violence to settle feuds, exterminating indigenous people, overworking or beating children, keeping slaves, lynchings and bullying of children were widely accepted. Now they occur rarely and are condemned universally.

It has been deeply moving to watch racial and sexual oppression follow those practices down the same path toward oblivion.

Bruce Peterson is a Hennepin County district judge. He teaches a course on lawyers as peacemakers at the University of Minnesota Law School.