If you bake a cupcake, the world has one more cupcake. If you become a circus clown, the world has one more squirt of seltzer down someone's pants. But if you win an Olympic gold medal, the world will not have one more Olympic gold medalist. It will just have you instead of someone else.

If it's okay to enrich ourselves by denying foreigners the right to earn a living, why shouldn't we enrich ourselves by invading peaceful countries and seizing their assets? Most of us don't think that's a good idea, and not just because it might backfire. We don't think it's a good idea because we believe human beings have human rights, whatever their colour and wherever they live. Stealing assets is wrong, and so is stealing the right to earn a living, no matter where the victim was born.

But when something is easy to imagine, it’s often because you’ve failed to imagine it in sufficient detail.

If you support protectionism because you think it’s good for you, you’ve probably just got your economics wrong. But if you support protectionism because you think it’s good for your fellow Americans, at the expense of foreigners, then it seems to me you’ve got your morals wrong too.

[Economics] is all about observing the world with genuine curiosity and admitting that it is full of mysteries