Key Arguments

• Rawls introduces "one further assumption to guarantee strict compliance": "The parties are presumed to be capable of a sense of justice and this fact is public knowledge among them. This condition is to insure the integrity of the agreement made in the original position."
• He clarifies that this does not mean they already apply a particular conception of justice in deliberation; rather, "it means that the parties can rely on each other to understand and to act in accordance with whatever principles are finally agreed to."
• Once principles are chosen, "the parties can depend on one another to conform to them" and "they know that their undertaking is not in vain: their capacity for a sense of justice insures that the principles chosen will be respected."
• At the same time, this assumption "still permits the consideration of men’s capacity to act on the various conceptions of justice": if a conception "is unlikely to generate its own support, or lacks stability, this fact must not be overlooked. For then a different conception of justice might be preferred."
• He emphasizes that the capacity assumed is purely formal and that the parties are rational in not entering agreements they cannot keep: "taking everything relevant into account, including the general facts of moral psychology, the parties will adhere to the principles eventually chosen. They are rational in that they will not enter into agreements they know they cannot keep, or can do so only with great difficulty. Along with other considerations, they count the strains of commitment (§29)."
• Thus "the persons in the original position are to assume that the one [conception of justice] they adopt will be strictly complied with. The consequences of their agreement are to be worked out on this basis."

Source Quotes

The idea of a game does not really apply, since the parties are not concerned to win but to get as many points as possible judged by their own system of ends. There is one further assumption to guarantee strict compliance. The parties are presumed to be capable of a sense of justice and this fact is public knowledge among them. This condition is to insure the integrity of the agreement made in the original position.

It does not mean that in their deliberations the parties apply some particular conception of justice, for this would defeat the point of the motivation assumption. Rather, it means that the parties can rely on each other to understand and to act in accordance with whatever principles are finally agreed to. Once principles are acknowledged the parties can depend on one another to conform to them.

Once principles are acknowledged the parties can depend on one another to conform to them. In reaching an agreement, then, they know that their undertaking is not in vain: their capacity for a sense of justice insures that the principles chosen will be respected. It is essential to observe, however, that this assumption still permits the consideration of men’s capacity to act on the various conceptions of justice.

The general facts of human psychology and the principles of moral learning are relevant matters for the parties to examine. If a conception of justice is unlikely to generate its own support, or lacks stability, this fact must not be overlooked. For then a different conception of justice might be preferred. The assumption only says that the parties have a capacity for justice in a purely formal sense: taking everything relevant into account, including the general facts of moral psychology, the parties will adhere to the principles eventually chosen.

The assumption only says that the parties have a capacity for justice in a purely formal sense: taking everything relevant into account, including the general facts of moral psychology, the parties will adhere to the principles eventually chosen. They are rational in that they will not enter into agreements they know they cannot keep, or can do so only with great difficulty. Along with other considerations, they count the strains of commitment (§29). Thus in assessing conceptions of justice the persons in the original position are to assume that the one they adopt will be strictly complied with.

Key Concepts

• There is one further assumption to guarantee strict compliance. The parties are presumed to be capable of a sense of justice and this fact is public knowledge among them.
• Rather, it means that the parties can rely on each other to understand and to act in accordance with whatever principles are finally agreed to.
• In reaching an agreement, then, they know that their undertaking is not in vain: their capacity for a sense of justice insures that the principles chosen will be respected.
• If a conception of justice is unlikely to generate its own support, or lacks stability, this fact must not be overlooked. For then a different conception of justice might be preferred.
• They are rational in that they will not enter into agreements they know they cannot keep, or can do so only with great difficulty. Along with other considerations, they count the strains of commitment (§29).

Context

Late §25, where Rawls supplements the motivational assumptions with a compliance condition and ties the choice of principles to considerations of psychological stability and strains of commitment.