The Common Sense Case for Liberty

by Bryan Caplan

Let me begin with a disclaimer: Despite his moral views, Robin is an incredibly nice, decent person. He wouldn’t hurt a fly. To know Robin is to love him. Robin Hanson, you complete me!

Nevertheless, Robin endorses an endless list of bizarre moral claims. For example, he recently told me that “the main problem” with the Holocaust was that there weren’t enough Nazis! After all, if there had been six trillion Nazis willing to pay $1 each to make the Holocaust happen, and a mere six million Jews willing to pay $100,000 each to prevent it, the Holocaust would have generated $5.4 trillion worth of consumers surplus.

Let’s consider another example. Suppose the only people in the world are Hannibal the millionaire, a slave trader, and 10,000 penniless orphan slaves. The slave trader has no direct use for his slaves, but likes money; Hannibal, on the other hand, is a ravenous cannibal. According to Robin, the “optimal outcome” is for Hannibal to get all 10,000 orphans and eat them.

If you’ve ever taken a class in moral philosophy, you’ve probably heard weird examples like these before. Normally, these examples lead people to back away from their pet moral theories. Robin’s devotion to efficiency is so strong, however, that he will bite any bullet you present. The most he’ll say in his own defense is that he is “Merely serving as an advisor to help people get what they want,” but the fact remains that faced with the preceding examples, he’d advise genocide and cannibalism.

Frankly, I think my grostesque examples reveal a fatal flaw not just in Robin’s efficiency standard, but in all one-sentence moral theories. It is absurd to latch on to an abstract grand moral theory, and then defend it against every counter-example.

Here’s my alternative: Sensible moral reasoning begins with concrete, specific cases. For example: It would be wrong for me to walk over to Robin right now and punch him. From there, we can start to generalize. It would probably be wrong for me to walk over and punch any of the people in this room. At the same time, we can note exceptions. If Robin had consented to box me, then punching him would be OK. In fact, it would probably be wrong not to try to punch him, because I’d be cheating you, the audience.

How far can you get with my approach? Very far. One straightforward moral generalization is that it is normally wrong to start using or threatening physical violence against others. Another is that it is normally wrong to take people’s property without their consent. Even children understand these norms: “Use your words,” and “That doesn’t belong to you.” On reflection, though, these norms are equivalent to the libertarian principles of respecting the life and property of others.

But isn’t libertarianism just another “abstract grand moral theory” subject to all kinds of devastating counter-examples? If you take libertarian principles as absolute, then the answer is Yes. As I speak, everyone in this room is shooting carbon dioxide molecules at other people without their consent.

Note, however, that I was careful to say that it is “normally” wrong to violate the liberty of others. If you’ve got a good reason to violate liberty, I’m open to it. “We’ll all die if we stop breathing” is a pretty good reason. In contrast, “Most of us want to rob them,” is an embarrassingly bad reason.

If this is really my view, why bother to study economics? My answer: When someone says there is a “good reason” for a regulation or a tax, we can use economics see whether the story holds water. If someone says that we need to restrict the liberty of American consumers to buy Japanese goods in order to prevent the destruction of the U.S. economy, we can see if the textbook chapter on international trade agrees. The same applies if someone says it would be more efficient to raise taxes and spend the revenue on education. Maybe the economics will check out, and we’ll have to think about whether we have a good enough reason to violate liberty. More often, though, the economics doesn’t check out – and we avoid violating the liberty of another human being for less than no reason at all.

If you ask me, “Can you prove that your moral view is correct?,” I could answer your question with another question: “Can Robin prove that his moral view is correct?” But I don’t want to dodge this challenge. The strength of my position is precisely that I’m not offering you a phony seventeen-step “proof that murder is normally wrong.” Instead, I begin with concrete, specific cases where morality is obvious, and reason from there. I don’t have a mathematical formula like “Maximize the sum of willingness to pay.” That’s OK. Unlike Robin, I’d rather be vaguely right than precisely wrong.