First of all, principles should be general. That is, it must be possible to formulate them without use of what would be intuitively recognized as proper names, or rigged definite descriptions.

Peace surely is a good reason, yes. But there are other reasons too.

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

You hear that liberalism lacks an idea of the common good, but I think that's a mistake.

There are various ways you might define the common good, but that would be one way you could do it.

We may suppose that everyone has in himself the whole form of a moral conception.

Thus I assume that to each according to his threat advantage is not a conception of justice.