Algebraic methods of integrating evidence have been suggested independently by writers on legal thought and writers on cognitive theory. These methods provide an interesting area for developing mutual interaction between legal thought and cognitive theory. The case of restitution provides a useful example for the study of algebraic schemes. A simple equation suggested by both legal thought and everyday morality is that the deserved punishment should equal the sum of the guilt (culpa) and the damage caused minus the restitution (recompense) paid. An experimental analysis to test this additive and subtractive formula used a scenario involving two stamp collectors, one of whom ruined some stamps belonging to the other. They were told to imagine that they were the victim and to say how much the offender should be punished. The three levels of guilt described accidental, careless, and intentional acts. The two levels of damage stated that 2 or 10 stamps were ruined. The three levels of restitution stated that none, half, or all of the stamps were replaced by the offender. The study participants were psychology students at the University of California at San Diego. Results showed that the guilt and damage integration was additive, but the other relations were not. Restitution had a paradoxically large effect. Discussion of implications, figure, and 28 references.