The hazards of the generalized prisoner's dilemma are removed by the match between the right and the good.

Ideally a just constitution would be a just procedure arranged to insure a just outcome.

There are infinitely many variations of the initial situation and therefore no doubt indefinitely many theorems of moral geometry.

A society regulated by a public sense of justice is inherently stable.

When the basic structure of society is publicly known to satisfy its principles for an extended period of time, those subject to these arrangements tend to develop a desire to act in accordance with these principles and to do their part in institutions which exemplify them

You might say that, if citizens are acting for the right reasons in a constitutional regime, then regardless of their comprehensive doctrines they want every other citizen to have justice. So you might say they're all working together to do one thing, namely to make sure every citizen has justice. Now that's not the only interest they all have, but it's the single thing they're all trying to do. In my language, they've striving toward one single end, the end of justice for all citizens.

What's important is that people give the kinds of reasons that can be understood and appraised apart from their particular comprehensive doctrines: for example, that they argue against physician-assisted suicide not just by speculating about God's wrath or the afterlife, but by talking about what they see as assisted suicide's potential injustices.