Nation states cause some of our biggest problems, from civil war to climate inaction. Science suggests there are better ways to run a planet.

By Debora MacKenzie

Try, for a moment, to envisage a world without countries. Imagine a map not divided into neat, coloured patches, each with clear borders, governments, laws. Try to describe anything our society does – trade, travel, science, sport, maintaining peace and security – without mentioning countries. Try to describe yourself: you have a right to at least one nationality, and the right to change it, but not the right to have none.

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