I posted the other day about John Rawls’s surprisingly illiberal closed society assumption. Other than the assumption’s general distastefulness, it also seems to cause some weird tension with other parts of Rawls’s justice as fairness. The reason that Rawls has the zero mobility assumption in the first place, I think, is so that participants in the original position thought experiment really do formulate a just society that they would be willing to accept no matter where in that society they ended up. This project would be undermined somewhat if it was possible to just go somewhere else if the society turned out to not be acceptable to a particular individual.
Rawls’s famous difference principle states that social and economic equalities are only justifiable to the extent that they benefit the least well off. When formulating his principles of justice, Rawls allows for the possibility that tax rates that are too high could push productive members of society out of the work force. One specific way that inequality can benefit the least well off is by encouraging the rich to do economically productive things that positively affect all members of society. Reducing inequality could hurt poor people if it causes a society’s elites to withdraw from the workforce.
But why is Rawls so careful to include the possibility of economic exit in his theory of justice, but just assume away political exit? Forced labor is unacceptably coercive, but forced membership is not? The distinction between the two seems somewhat arbitrary.