In the physical world, Isaac Newton postulated, every action produces an equal and opposite reaction. In the world of politics and society, the same is true — except the reaction is sometimes more than equal. Barack Obama’s presidency proved it, and Donald Trump’s offers new confirmation.

History doesn’t move in a straight line. When the first African-American was elected president, it suggested that racism was on the wane and bigots were an endangered species. “His talent was to project an idealized vision of a post-racial America,” Hoover Institution senior fellow Shelby Steele wrote immediately afterward. “Obama’s special charisma — since his famous 2004 convention speech — always came much more from the racial idealism he embodied than from his political ideas.”

But the hope of a harmonious reconciliation was premature. Obama stirred latent and not-so-latent racial fears and resentments among many whites, who found him threatening no matter how hard he tried to transcend the color line. Among blacks, it roused expectations of rapid progress that didn’t come, and a series of police shootings of black men reinforced a sense of estrangement from those in power.

One of the whites embittered by Obama was Trump, who began to build a following by feeding suspicions that Obama is a Muslim who was born abroad. But at that point, the New York tycoon was merely a symptom of white dismay. By last fall, a majority of whites and a plurality of blacks said that race relations had gotten worse, not better, under Obama.

They got a thunderous vindication from the election of Trump, who lost to Hillary Clinton among blacks, Hispanics and Asian-Americans but carried the vote of the nation’s predominant race. Six months into his presidency, Atlantic writer Ta-Nehisi Coates notes, Trump’s approval rating was “underwater with every single demographic group. Every demographic group, that is, except one: people who identified as white.”

Race is not the only important key to feelings about Trump. His primitive attitude toward females worked to his advantage among some voters against Clinton. But it also helped to mobilize huge post-inauguration demonstrations on behalf of women’s rights — including half a million protesters in the nation’s capital.

Clinton’s shortcomings as a candidate blunted the historic appeal of her candidacy. But Trump’s appeal wore off faster among females.

Trump has been an unintended boon to the cause of sexual equality. Just as Obama stimulated anxiety among many whites, Trump has provoked disgust among many women. One reason is the indelible stain of his infamous “Access Hollywood” tape, in which he said: “I’m automatically attracted to beautiful — I just start kissing them. It’s like a magnet. Just kiss. I don’t even wait. And when you’re a star, they let you do it. You can do anything.”

In past campaigns, a revelation of that kind would have been fatal — particularly because a parade of women came forward to accuse Trump of doing exactly what he admitted. This was just one of many established limits that Trump punctured on his unlikely journey to the White House.

But the new reality was not stable. Trump’s ability to get away with vile behavior provoked some women to expose men who had victimized them.

The president gloated when such critics as movie mogul Harvey Weinstein and Sen. Al Franken, D-Minn., were brought down by charges against them. But every time a prominent man is toppled by revelations that he abused women, it reminds everyone that Trump did the same and got away with it. Now, he finds his past behavior under new scrutiny, under new standards.

Trump has helped to create a new environment that is increasingly hospitable to his enemies.

    

Steve Chapman blogs at http://www.chicagotrib une.com/news/opinion/chapman. Follow him on Twitter @SteveChapman13 or at https://www.facebook.com/stevec hapman13. To find out more about Steve Chapman and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.