Patriotism involves a love of home and a preparedness to defend it; nationalism, by contrast, is an ideology, which uses national symbols to conscript the people to war. When the Abbé Sieyès declared the aims of the French Revolution, it was in the language of nationalism: “The nation is prior to everything. It is the source of everything. Its will is always legal…. The manner in which a nation exercises its will does not matter; the point is that it does exercise it; any procedure is adequate, and its will is always the supreme law.” Those inflammatory words launched France on the path to the Reign of Terror, as the “enemies of the nation” were discovered hiding behind every chair.

But those who dismiss the national idea simply because people have threatened their neighbors in its name are victims of the very narrow-mindedness that they condemn. A small dose of evolutionary psychology would remind them that human communities are primed for warfare, and that when they fight, they fight as a group. Of course they don’t put it like that; the group appears in their exhortations as something transcendent and sublime—otherwise why should they fight for it? It goes by many names: the people, the king, the nation, God, even the Socialist International. But its meaning is always the same: “us” as opposed to “them.”

Divide a classroom of children into those wearing red pullovers and those wearing green and then make a few significant discriminations between them. You will soon have war between the reds and the greens. Within days, there will be heroes on each side and acts of stirring self-sacrifice, maybe in the long run a red anthem and a green. Red and Green will become symbols of the virtues and sacrifices of their followers, and—like national flags—they will acquire a spiritual quality, leading some to revere a cloth of red, others to burn that cloth in an act of ritual vengeance. That is not a reason for abolishing the color red or the color green.