Condign merit supposes an equality between service and return; it is measured by commutative justice, and thus gives a real claim to a reward in the name of Christ.
Congruous merit, owing to its inadequacy and the lack of intrinsic proportion between the service and the recompense, claims a reward only on the ground of equity.
This early-scholastic distinction and terminology, which is already recognized in concept and substance by the Fathers of the Church in their controversies with the Pelagians and Semipelagians, was again emphasized by Johann Eck, the adversary of Martin Luther.
), there are also other meritorious works which at most are entitled to reward or honour for reasons of equity or mere distributive justice, as in the case of gratuities and military decorations.
From an ethical point of view the difference practically amounts to this that, if the reward due to condign merit be withheld, there is a violation of right and justice and the consequent obligation in conscience to make restitution, while, in the case of congruous merit, to withhold the reward involves no violation of right and no obligation to restore, it being merely an offence against what is fitting or a matter of personal discrimination.