The result, Piketty argues, is a political system that pits two top-down coalitions against each other:

In the 1950s-60s, the vote for left-wing (socialist) parties in France and the Democratic Party in the US used to be associated with lower education & lower income voters. It (the left) has gradually become associated since 1970s-80s with higher education voters, giving rise to a multiple-elite party system: high-education elites vote for the left, while high-income/high-wealth elites for the right, i.e., intellectual elite (Brahmin left) vs business elite (merchant right).

Changes in the structure of the electorate emerged in force during a period of unprecedented upheaval in the 1960s, when a combination of liberation movements — committed to civil rights, women’s rights, sexual freedom, the student left, decolonization and opposition to the Vietnam War — swept across Europe and the United States.

In this country, Democratic reforms adopted after the 1968 convention — an event marked by police violence against antiwar demonstrators — produced a radical shift in power within the Democratic Party.

Before reform, Byron Shafer, a political scientist at the University of Wisconsin, writes in “Quiet Revolution: The Struggle for the Democratic Party and the Shaping of Post-Reform Politics,”

there was an American party system in which one party, the Republicans, was primarily responsive to white collar constituencies, and in which the other, the Democrats, was primarily responsive to blue collar constituencies.

After reform, Shafer contends,

there were two parties each responsive to quite different white collar constituencies, while the old blue collar majority within the Democratic Party was forced to try to squeeze back into the party once identified predominately with its needs.

Shafer’s white collar constituency is, in fact, what Piketty describes as “a higher education” or “intellectual” elite — his “Brahmin left.”

In support of Piketty’s argument: In 1996, according to exit polls, the majority of voters who cast ballots for Bill Clinton were what demographers call non-college. That year, his voters were split 59 percent non-college to 41 percent college graduates. Twenty years later, the majority of voters for Hillary Clinton were college graduates, at 54.3 percent, compared with 45.7 percent non-college.

Exit polls show substantially larger numbers of college-educated voters than the surveys conducted by American National Election Studies. But the ANES data also shows a sharp increase in the percentage of voters with college and advanced degrees supporting Democratic presidential candidates. In 1952 and 1956, for example, the Democratic nominee, Adlai Stevenson, got 29 and 31 percent of the college-educated vote. In 2012, the most recent year for which ANES data is available, 53 percent of those with at least a college degree voted for Barack Obama.