It was gun violence that finally drove California to secede from the United States.

A series of mass shootings culminated in a savage attack on a Sacramento-area school that killed 35 kids and two cops. The shooters used rifles, pistols, and large-capacity magazines — weaponry that had been illegal in California until the U.S. Supreme Court threw out the state’s gun control laws. Californians raged that the conservative justices had effectively murdered their children.

That anger spiraled into a cold civil war, with California’s elected leaders openly defying federal officials and laws by outlawing most guns. An authoritarian Republican president retaliated with an economic blockade of the state. After right-wing militias invaded the state and massacred California Highway Patrol officers, the governor declared her intention to depart the Union, subject to the result of a referendum by voters.

This path to California nationhood is fiction, at least for now. But this account — invented by the writer David French in his 2020 book Divided We Fall: America’s Secession Threat and How to Restore Our Nation — might be the most realistic scenario for a Calexit that I’ve encountered.

The scenario packs a special power because French is a careful, rigorous thinker who desperately wants the United States to remain united. A lawyer, military veteran, and champion of socially conservative causes, he is also loyal to the American tradition of pluralism: he broke early and decisively from allies to oppose President Trump and harsh partisanship. His book is a fair-minded examination of how Americans, across not just the political spectrum but also the nation’s geography, have started to loathe those with whom they disagree.

French argues that this negative polarization is so extreme that the country may well split apart. To demonstrate how real the threat is, he offers two all-too-possible scenarios — a Texas departure rooted in abortion politics, and a guns-rights clash in California.

The Calexit scenario is based on Californians’ fears of minority, illegitimate rule because of problems with the Senate, Electoral College, and Supreme Court.

In French’s Calexit scenario, Republicans eliminate the Senate filibuster to give their president extraordinary powers to subdue California. The Supreme Court is stacked with conservatives because Republicans had blocked previous appointments by Democratic presidents. Californians see the president as illegitimate because he lost the popular vote in an election marked by voter suppression.

When California’s governor declares her independence referendum, she asks the president to respect the results of the vote. The Republican commander-in-chief, recognizing that California’s departure will ensure a conservative-dominated America, seeks to encourage Californians to leave the Union. He pursues a conservative that is anathema to California, and indicates that if Californians vote to remain in the Union, the state will be put under military rule.

So, Californians vote overwhelmingly to leave the Union. Soon Oregon and Washington join them.

French thinks Americans can prevent such a split of their country by embracing tolerance and pluralism. He defends “the rights of communities and associations to govern themselves according to their values and their beliefs — as long as they don’t violate the fundamental rights of their dissenting members.”

Despite his conservative views, he argues, in service of national unity, for letting progressives in states like California go their own way.

If Americans don’t rediscover pluralism, the results will be bad not just for the country, but for the world, French argues. With the U.S. distracted by its own breakup, French suggests, China could seize Taiwan, Russia could reclaim Eastern Europe, and other secessionists conflicts could escalate.

That’s a sobering analysis. But by this Californian’s lights, the final results of French’s Calexit scenario don’t sound so bad. New England creates its own democratic nation. Millions of Americans relocate to places better aligned with their politics. And Californians seem happier.

Joe Mathews writes the Connecting California column for Zócalo Public Square.