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Today I want you to divide yourselves into separate groups, and I am going to divide you by the color of your eyes. Who has blue eyes? Sit over here. Who has brown eyes? Sit over there. Who has green eyes? You sit here.

Now suppose I told you that from this moment on, you must not like anyone who isn’t in your group. If you have brown eyes, you aren’t supposed to like anyone with blue eyes. If you have green eyes, you must hate everyone with brown eyes, and so on. They are different from you. They’re bad. You can’t trust them, and they are not as nice as you.

Does that make any sense to you? Should we like some people because their eyes are the same color as ours, and not like other people because their eyes are a different color?

You probably know that even children have …