The recent independence referendums in Iraqi Kurdistan and Catalonia, and the predictable heavy-handed responses from the central governments in Baghdad and Madrid, have raised many questions — a catechism without answers — on the meaning of nationhood in the 21st century. What is a nation? What is a nation-state? Is it the same as a country? Are a people, or a tribe, the same thing as a nation? In a globalized economy what does national sovereignty really mean? My guess is most Americans don’t think of these questions. They live in “One Nation Indivisible,” even if their country doesn’t feel that way these days. But “what is a nation?” is a question that has been asked with urgency in many parts of the world in the almost three decades since the end of the Cold War. Fifteen new/old nations emerged out of the Soviet Union alone. Its European satellites also redefined themselves. Within five years of the fall of the Berlin Wall, East Germany agreed to be effectively purchased by the West Germans. Czechoslovakia became two nations, created out of negotiation. Yugoslavia eventually became seven countries brought forth upon this earth in bloodshed. Not all groups have succeeded in the push for a nation-state of their own. The Kurds, despite appalling repression, have never stopped trying to create a nation of their own. To understand this urge to redraw the map you need to look at modern imperial history. Kurdistan and Yugoslavia’s borders were fixed when the defeated Ottoman and Austro-Hungarian empires were carved up at the end of World War I. These boundary lines had very little to do with national aspirations and everything to do with the convenience of the victorious empires, Britain and France. The borders were maintained by the imperial powers that supplanted the British and French after World War II, the United States and the Soviet Union. The challenge to the existing idea of nationhood began with the end of Communism. It expanded when Western nations began to fissure following the financial crash of 2008. Brexit came out of an internal argument Britons have been having since the crash about what their nation is and should be. The crash increased support for the Scottish Nationalist Party, which won a majority in the Scottish Parliament in 2011. In 2014, Scottish voters were asked in a referendum, “Should Scotland be an independent country, yes or no?” The no’s had it. But that wasn’t the end of the story because English nationalism had been aroused. In 2016, David Cameron, the British prime minister, having won the Scottish referendum, decided to try his luck again by offering a vote on Britain’s continued membership in the European Union: “Should the United Kingdom remain a member of the European Union or leave the European Union?” The argument against continued membership in the union was made in terms of national sovereignty. It was not a new argument. When the European Union began its slow march toward a federal future in the late 1980s, Britain balked at joining the process. In Margaret Thatcher’s view, joining a federal Europe meant the end of Britain’s national independence. Britain, because of its size and importance within the European Union, was able to opt out of the foundational arrangements of this federal Europe: the Schengen Agreement, which allows free movement of people over national borders, as well as the single currency, the euro. Fear about sovereignty did to normally pragmatic English minds what fear does to most minds: It made them irrational. During the Scottish referendum the European Union made it clear to Scots that if they voted for independence they would not be fast-tracked into the union and could not use the euro as its currency. No greater endorsement of British sovereignty could have been imagined. Didn’t matter. When the votes were counted, 53 percent of English voters opted to leave while 62 percent of Scots voted to remain. Two very distinct expressions of national will, but only one is being acted on. How much did Catalonia’s decision to hold an independence referendum vote owe to the Scottish vote? Did Carles Puigdemont, leader of the Catalan Parliament, make a mistake in assuming that the precedent of peaceful voting in Britain on Scottish independence meant Catalans could have their vote in a similarly respectful atmosphere? Didn’t he know that a European Union pledge to respect the sovereignty of its existing members would not intervene when the Spanish government sent in the Guardia Civil to stop it? The Catalan crisis leads to a final question about nationhood: Can Western Europe’s nations hope to preserve their wealth and high living standards in a globalized economy without pooling their nationhood into something greater? The beginning of an answer to this contemporary question comes from the past. Around 500 years ago, at another time of political and economic flux, a Polish nobleman, whose name is lost to history, was asked about his national identity. He responded, “I am of the Polish nation, of the Lithuanian citizenship, of the Ruthenian people, and of Jewish origin.” The answer anticipates the view of Albert Rivera, who leads an anti-independence center-right party in Catalonia: “Catalonia is my homeland, Spain is my country and Europe is our future.” Can Europe become a nation? That’s one of the biggest questions of the 21st century.