Chisholm prefers to formulate these claims about the fittingness of certain emotional reactions to certain objects by appeal to a fundamental concept in his ethics. This is the concept of requirement. Instead of saying that it is correct, or fitting, to have a certain emotional reaction to a certain object, we can say that contemplation of that object requires that emotional reaction. With these concepts at our disposal, Chisholm suggests, we can define all the central concepts of ethics ([B&amp;IV], 53).