Republican Richard M. Nixon narrowly managed to win the 1968 presidential election by exploiting the issue of law and order amid a climate of fear and insecurity. Now Republican Donald J. Trump has declared that he is the candidate of law and order in 2016 and vowed to secure the borders, prevent terrorism, and end violence against the police.

Could Trump win the presidency on this platform? The latest polls indicate that he has a reasonable chance. But despite what some pundits have pronounced, a closer analysis of the historical analogy between 2016 and 1968 reveals significant differences and suggests that law and order may not give Trump the decisive edge it provided Nixon.

First and foremost, the nation seemed on the brink of chaos and collapse in 1968. Crime in the streets was rising and protests on campus were commonplace. The assassination of Dr. Martin Luther King, Jr. led to riots in more than one hundred cities, including Washington. The murder of presidential candidate Robert Kennedy and clashes at the Democratic Convention in Chicago eroded popular faith in peaceful change and the political process.

Society was also evolving. The sexual revolution and the drug culture were spreading. The women’s movement was growing. And the hippie phenomenon was emerging. For moral traditionalists, it was the perfect storm.

In that troubled climate, law and order was the perfect slogan for Nixon. Amorphous and abstract, it served as a Rorschach test for anxious voters, who could project onto it whatever fear was uppermost in their minds at the moment. For Trump the slogan could also serve as a vehicle for white voters with concerns about globalization or immigration. ...