A Call for a Possible World Argument in Ethics

Ethical theories must be able to deal with not only actual situations, but also counterfactual situations. By applying a possible world argument (PWA) in which we consider a theory's applicability over the space of possible worlds, we see more clearly whether the theory is world-sensitive or not (flexible or nonflexible). In this essay I will argue for the importance of PWA and show, through a case study, how different theories react to PWA. The conclusion will be open-ended: We need to have a clearer picture of moral psychology before we can settle for either a flexible or nonflexible theory in accordance with which we should live.