A Vote to Leave campaigner holds a placard on May 25 in Bolton, England. (Christopher Furlong/Getty Images)
Opinion writer

The age of autarky is again upon us.

Britain, in two weeks, will vote on whether to leave the European Union, that great postwar project to promote both peace and prosperity.

No matter that economists have almost uniformly warned that a possible “Brexit” would devastate the British economy, with an estimated cost of approximately $6,000 per British household. Disregard news that markets are already freaking out about the consequences for the pound and the overall financial sector; that high-skilled talent has become skittish about moving to the British isles, whose relationship to the E.U. in a post-Brexit world is as yet unknown; and that foreign clients have begun suspending or delaying contracts with British companies.

Who cares that these small islands, so dependent on the continent for both what they consume and where they send their exports, are putting so much economic activity at risk?

Many Brits want to withdraw, to show they’re separate and politically self-determined and not really into all this expensive pan-ethnic, pan-European unity rubbish. So withdraw they might. Recent polls show the “leave” and “stay” contingents about evenly split.

As Britain's main opposition leader, Jeremy Corbyn, jumps into the Brexit debate, opinion polls hint at an evenly divided electorate. (Reuters)

Financially self-defeating as it may seem, the British are hardly alone in their flirtation with economic, political and cultural separatism.

Other E.U. exit portmanteaus — Grexit, Itexit, Spexit — speckle the headlines. Within Spain, Catalonians have once again been agitating for independence. Secessionists in the Flanders region of Belgium have reawakened. Even within Britain itself, Scotland not so long ago held a referendum to disunite from the United Kingdom.

Farther east, Russia has engaged in its own jingoistic displays of economic separatism, bulldozing tons of foreign foods and shutting off access to additional imports. (This has of course contributed to the great cheese surplus in the United States.)

Likewise China, once seen as moving toward greater economic and cultural openness, has lately taken a more nationalist, xenophobic and protectionist approach. This spring the government even launched a propaganda campaign warning citizens not to get too cozy with handsome foreigners.

And of course here at home in the United States, all three of our remaining major-party presidential candidates — Donald Trump, Bernie Sanders and Hillary Clinton — have embraced anti-trade talk.

Of the three, Trump has offered the most isolationist, nationalistic vision, themed “America First.” To Trump, trade and diplomacy are never Pareto-improving — that is, making everyone better off without making anyone worse off — but always zero-sum. He not only laughs off the dire consequences of a trade war, he also actively stokes xenophobia at home and advocates large-scale disengagement from our allies abroad.

In a way, these international developments — or at least their near-simultaneity — are a bit surprising.

We live in an age of unprecedented globalization. First mass media and then social media exposed us to the ideas, products and languages of our most far-flung counterparts around the world. Advances in finance, technology and logistics have facilitated more trade, and trade in a richer variety of goods and services, than at any time in human history.

And yet — either despite these advances in globalization or perhaps because of them — countries, regions and peoples worldwide are suddenly, synchronously retreating from one another and turning inward. Around the world, citizens are ignoring the improvements in living standards that have resulted from centuries of exchanges of ideas, products and customs, and are instead clamoring for more seclusion.

For the first time in history, no island is truly an island. Yet increasingly, countries and peoples hope to moat themselves off from the economic, political and cultural influences of others. We are more interconnected with others than ever before, and our response is to try to disconnect.

We’ve seen similar embraces of economic and intellectual autarky in the past. They’ve generally ended badly.

North Korea (not coincidentally, a Trump endorser) for decades has practiced “Juche,” typically translated as “self-reliance.” In practice it means sealing oneself off from the rest of the world economically and culturally, and it has led to starvation and poverty.

Earlier precedents for deliberate pursuit of autarky include Burma under its military junta, as well as a host of mid-20th-century dictatorial leaders (Spain under Franco, Italy under Mussolini, Germany under Hitler, China and its Cultural Revolution under Mao).

The United States too, briefly, instituted a deliberate policy of isolationism and complete trade embargoes, in the early 19th century under President Thomas Jefferson. It ravaged coastal shipping areas and was quickly reversed.

Each time, autarky has been presented as an antidote for some combination of economic malaise and ethnic unrest. Each time, countries have conflated isolationism with independence, and splintering with self-determination.

Economic “self-sufficiency” is just so easy to buy in to — until you realize how much it costs.