Abstract

The thesis explores the question of how should a rational moral agent reason and make choices when he finds himself accepting inconsistent moral judgments. It is argued that it is both conceptually and psychologically justified to describe such an agent as suffering from uncertainty. Such uncertainty, however, is not uncertainty regarding the truth of some descriptive claim, but rather uncertainty regarding the truth of a normative claim. Specifically it is uncertainty regarding the truth of a moral judgement. In the literature this is sometimes called “moral uncertainty”. Two different lines of philosophical literatures that explore the idea of moral uncertainty are discussed. The first line – the one that originated from David Lewis‟ argument against the “Desire as Belief Thesis” – explores the mere possibility of moral uncertainty, while the second line explores the question how ought a rational moral agent choose in face of moral uncertainty. The discussion of these two lines of research leads to the conclusion that a consistent account of moral decision making under conditions of moral uncertainty that will be applicable to the kind of cases that the thesis explores, must make use of degrees of beliefs in comparative moral judgements and of them alone. Specifically, no references to degrees of moral value should be made. An attempt to present such an account in the framework of an extension of Leonard Savage‟s model for decision making is carried out. This attempt leads to a problematic result. Several implications of the result to ethic and meta-ethics are discussed as well as possible ways to avoid it. The conclusion is partly positive and partly negative: While a plausible account of moral decision making under conditions of moral uncertainty is presented, an account of moral reasoning that aims at finding a complete moral theory is shown to be a very difficult – if not impossible - aim to achieve.