Moral Dilemmas and the Contrary-to-Duty Scenarios in Dynamic Logic of Acts of Commanding - The Significance of Moral Considerations Behind Moral Judgments -

摘要

In the literature on deontic logic, there have been many proposals to weaken or abandon some of the principles of standard deontic logic so that moral dilemmas can be accommodated without triggering deontic explosion. Since the so-called principle (D) precludes the possibility of moral dilemmas in standard deontic logic, such proposals usually include the rejection of (D). If we abandon (D), however, it is possible to avoid deontic explosion in most real cases without abandoning or weakening any other principles of standard deontic logic. What is important to note here is the fact that the moral consideration that leads to a moral dilemma can be divided into two or more moral sub-considerations in such a way that each of them leads to one of the conflicting moral judgments that jointly constitute the very dilemma in question. Then by personifying the sub-considerations as different command giving authorities, we can represent such a moral dilemma as an example of a deontic dilemma generated by conflicting commands given to one and the same agent by different authorities without triggering deontic explosion in a dynamic logic of acts of commanding that extends multi-agent variant of standard deontic logic without (D). The basic idea is to relativize deontic operators to commandees and commanders. This enables us to "minimize" the possibility of deontic explosion, so to speak. Deontic explosion occurs only when a set of conflicting commands are given to one and the same commandee by one and the same commander or a self-contradictory command is given. But then, in the case of acts of commanding, a rational commander has every reason to avoid such a situation, and in the case of moral dilemmas, we show that it is always possible to divide the moral consideration that leads to a dilemma into two or more moral sub-considerations. We then show how contrary-to-duty scenarios can be formalized in the same dynamic logic. We apply the same personification of moral sub-consider