National self-determination, the principle that US President Woodrow Wilson put on the international agenda in 1918, is generally defined as the right of a people to form its own state.
The independence referendums in Iraqi Kurdistan and Catalonia are the latest examples showing why that principle is so often difficult to apply.
With some 30 million Kurds divided among four states (Iraq, Turkey, Syria, Iran), nationalists argue that they deserve the world’s recognition.
In Spain, some 7.5…