A Dialogue:

Philosopher:  “A perfectly just society would look like X.”

Economist:  “That’s unrealistic. In real life, people would respond badly to the incentives produced in X.”

Philosopher:  “Sure, but in a perfectly just society, people would not act like that. They would be motivated by a sense of justice and do what is morally right.”

Economist:  “That’s unrealistic. In real life, people don’t have a perfect sense of justice. Their sense of justice is endogenous to the institutions they live under and the demands placed upon them.”

Philosopher:  “I didn’t say X was ‘realistic’ in that sense.”

Economist: “Then why are you talking about X?”

Philosopher: “Uh, because I want to know what a perfectly just society would be like.”

Economist: “Oh, yeah, you did say that. I guess my objections were completely irrelevant. Sorry.”

 

An Aphorism (based on G.A. Cohen): 

Tasty grapes aren’t made any less tasty by being out of reach.

 

A Thought Experiment:

(This comes from David Estlund, with some colorful additions from me.) Imagine we’re out looking for a picnic spot. Atop a hill in the distance we see a beautiful flower-covered spot. We realize that it’s the perfect spot. Any other place we could have a picnic would be inferior to the spot on the hill. Should we try to go to the hill? Unfortunately, there’s a deep spike-filled ravine between the hill and us, and before the ravine, there’s a river filled with crocodiles. So, because it would be so hard to get to the spot, we shouldn’t bother go. However, it’s still the case that the spot in the distance is better than the spot we’re in.

 

The Lesson

One task—though by no means the only task—for political philosophy is to identify principles of justice and to ask what regimes could, in principle, perfectly realize those principles. Let’s refer to this as the identificatory task.

When you ask what regimes could perfectly realize those principles, you should imagine that every moral agent in that society will do whatever justice requires of him or her. (Or, at least, that if they don't, they will be blameless for it.) After all, if people aren’t willing to do what justice requires, then the society isn’t fully just for that very reason. You aren’t doing the identificatory task anymore. You’ve changed the question. So, for instance, I might say that in a perfectly just society, no one would abuse power. That doesn’t make me stupid or naïve. I know in the real world real people abuse power, and often the more power you give a person, the more likely she is to abuse it. But if I want to know what a perfectly just society would look like, I need to imagine a society where people would not abuse power. If people in a society would abuse power, then that society is for that very reason less than perfectly just.

You might say, “I’m not interested in knowing what a perfectly just society would be like.” Okay. I am.

You might say, “But there are more interesting moral questions than the question of what a perfectly just society would look like.” I agree. That’s one reason why my published writing is rarely on the topic of what a perfectly just society would be like. A Brief History of Liberty is not 220 pages of Rawlsian ideal theory. It's an account of why in the real world protecting negative liberty promotes positive liberty and other values.

You might say, “If we want to know what institutions are overall the best in the real world, we have to take people as they are—warts and all.” Yep. But that’s a different task than the identificatory task.

Suppose some philosopher defends some principles of justice J. You then point out that real people are unlikely to be motivated by J. But, so what? The mere fact that people won’t abide by J doesn’t show us that there’s anything wrong with J. We need to know why people won’t comply with J. If the reason is the reason is that they are too selfish, maleficent, or corrupt, that’s a problem with them, not a problem with J. The fact that people aren’t willing to comply with J shows that J is defective only if people have morally appropriate reasons for non-compliance, such as that J violates their personal prerogative or treats them badly. But then that shows that J was an incorrect theory of justice to begin with.

I am wary of misusing ideal theory. Some philosophers make the mistake of thinking that just because we’ve identified the perfect picnic spot, we should therefore do everything in our power to get there. That’s not right—sometimes we need to admit that we can’t swim past the alligators or jump over the ravine, or that the cost of getting there isn’t worth the added value of the perfect spot. Some philosophers do try to instantiate institutions that would work in ideal circumstances but fail in our circumstances. 

However, I am also wary of the tendency I see among many classical liberals to disavow ideal theory and to disavow the identificatory task. By doing so, they cede the moral high ground to their critics. (Maybe they intend to.)

I’ll end with a plug for John Tomasi’s forthcoming book. One virtue of his work is that he stays at the level of ideal theory. He argues not merely that neoclassical liberal regime-types can perfectly realize liberal justice, but that Rawls’s favored regime-types (e.g., property-owning democracy and liberal socialism) cannot.