In this chapter, we are going to show how the study of two psychopathological disorders, obsessive-compulsive disorder and major depression disorder, allows differentiating two feelings of guilt: deontological and altruistic. Deontological guilt arises from the transgression of internalized moral norms. Altruistic guilt is experienced when individuals believe that they have acted incongruously with others’ altruistic reasons. Our proposal is in line with other earlier psychological approaches to guilt, which consider two elements necessary to experience guilt: harm to a victim and the transgression of an internalized moral norm. It differs from previous approaches because it argues the possibility of experiencing guilt even if only one of these two components is present; indeed, the two types of guilt are independent of each other. Our approach allows us to demonstrate that the basis of any internalized moral norm is not an altruistic goal and that the basis of every altruistic behaviour is not the goal of respecting a moral norm.