In 1987, Ronald Reagan gave one of the pivotal speeches of his career. “There is one sign the Soviets can make that would be unmistakable, that would advance dramatically the cause of freedom and peace. General Secretary Gorbachev, if you seek peace, if you seek prosperity for the Soviet Union and Eastern Europe, if you seek liberalization, come here to this gate. Mr. Gorbachev, open this gate. Mr. Gorbachev, tear down this wall!” Three decades later, the world is still debating the building and tearing down of walls. We mostly hear about the one Donald Trump proposes on the US-Mexican border. But “America is not alone. Across Europe, the politicians with momentum are those who argue that the world is a nasty, threatening place, and that wise nations should build walls to keep it out.” The Economist on the new political divide. Farewell, left versus right. The contest that matters now is open against closed.