The authors did not foresee how older white voters would swing over to the Republican side and the way many assimilated Hispanics would vote like non-Hispanic whites. The failure of that book’s predictions has scared people off from making demographic forecasts.

But it’s hard to look at the generational data and not see long-term disaster for Republicans. Some people think generations get more conservative as they age, but that is not borne out by the evidence. Moreover, today’s generation gap is not based just on temporary intellectual postures. It is based on concrete, lived experience that is never going to go away.

Unlike the Silent Generation and the boomers, millennials and Gen Z voters live with difference every single day. Only 16 percent of the Silent Generation is minority, but 44 percent of the millennial generation is. If you are a millennial in California, Texas, Florida, Arizona or New Jersey, ethnic minorities make up more than half of your age cohort. In just over two decades, America will be a majority-minority country.

Young voters approve of these trends. Seventy-nine percent of millennials think immigration is good for America. Sixty-one percent think racial diversity is good for America.

They have constructed an ethos that is mostly about dealing with difference. They are much more sympathetic to those who identify as transgender. They are much more likely than other groups to say that racial discrimination is the main barrier to black progress. They are much less likely to say the U.S. is the best country in the world.

These days the Republican Party looks like a direct reaction against this ethos — against immigration, against diversity, against pluralism. Moreover, conservative thought seems to be getting less relevant to the America that is coming into being.

Matthew Continetti recently identified the key blocs on the new right in an essay in The Washington Free Beacon. These included the Jacksonians (pugilistic populists), the Paleos (Tucker Carlson-style economic nationalists), the Post-Liberals (people who oppose pluralism and seek a return to pre-Enlightenment orthodoxy). To most young adults, these tendencies will look like cloud cuckooland.