THE white working-class men who are planning to vote for Donald J. Trump this November have been called many things: xenophobic, racist, misogynist, dangerously naïve. But even if those descriptions are true, it doesn’t mean these men were fated to be Trump supporters. Recent research in social science and history suggests that they might have been out front in the fight against Mr. Trump — if only the American labor movement weren’t a shell of its former self.

When we think about unions, what typically come to mind are interest groups concerned with wages, benefits and working conditions. Scholars, however, have shown what everyone in politics knows instinctively: Unions are also political organizations that, under the right circumstances, can powerfully channel the working-class vote.

A classic study on this subject was done by the sociologist Seymour Martin Lipset. In a 1959 paper, he demonstrated that while the working class in most countries favors economic liberalism, it also displays an authoritarian streak. Using evidence from surveys, Mr. Lipset found blue-collar workers to be less committed to democratic norms like tolerance for political opponents, preference for rational argumentation over charismatic appeals and support for the rights of ethnic and racial minorities.

These tendencies, he claimed, were a function of lower levels of education and the isolation of many workers (for example, coal miners) from people who were different from them. Authoritarian attitudes also owed something to the work itself. Controversially, he suggested that manual work was at odds with the abstract thinking required to appreciate complex, pluralistic solutions to political problems.