I like economists, and I like trying to talk philosophy with them, even though they often find it boring and irritating. And they don’t like Rawls, but they tend to only know parts of A Theory of Justice. You know what part I mean – the rational choice stuff that they think is too simple and all wrong (and, honestly, isn’t the best).
What I’d like to do today is outline, in a simplistic and outrageously rough way, the later Rawls for economists, the Rawls I like most. Here’s the basic idea. In TJ, Rawls argued that people should be able to endorse complying with just institutions as good for them. But he later said he assumed too much agreement on the good life: people’s utility functions were modeled too similarly. So in Political Liberalism, Rawls lets peoples’ utility functions vary a lot. Now, these aren’t just any utility functions; they include the satisfaction one gets from getting one’s way morally and politically. So the utility functions contain moral commitments. Economists don’t like that, but utility analysis is pretty devoid of psychological content in itself, so there’s no reason it can’t be applied in the way I suggest.
Rawls’s goal, then, is to show that his conception of justice is a Pareto improvement vis-a-vis other conceptions of justice, especially illiberal ones, at least for the utility functions of a limited class of persons who are reasonable. Economists, you can understand reasonable people as those who play assurance games when they could play prisoner’s dilemmas.
So an overlapping consensus is just a bargaining point between people with heterogeneous utility functions, but among people who play assurance games, so the bargain can seem reciprocal and not based on mere threat advantage.
In short, a public justification for a law obtains when the law is an improvement in utility for each reasonable utility function and worse for none. Public justification is a Pareto concept.
Public reasoning, on the other hand, is about signaling. See, we might not know if some law or policy is publicly justified, so we need a way to convey that to others. Rawls thought we could talk in terms of shared values, or give arguments derived from what we agree on, and that way we could convince each other a public justification obtains. When a public justification obtains, it becomes common knowledge through signaling, and a publicity condition is met. Then people can see a point in complying with the relevant legal requirements. It is better for them to comply, they know it is better for others to comply, and they know that they and others are prepared to cooperate so long as others do.
The result is a well-ordered society, one where a conception of justice is stable, based on the moral considerations that comprise each person’s utility function. Reasonable people are often defined as prepared to comply with the rules, which is why Political Liberalism can be seen as a kind of ideal theory, for better or worse.