 Until recently, problems of risk have not been treated systematically in moral philosophy. A possible defence of this limitation is that moral philosophy can leave it to decision theory to analyse the complexities that indeterminism and lack of knowledge give rise to in real life. According to the conventional division of labour between the two disciplines, moral philosophy provides assessments of human behaviour in well-determined situations. Decision theory takes assessments of these cases for given, adds the available probabilistic information, and derives assessments for rational behaviour in an uncertain and indeterministic world. On this view, no additional input of moral values is needed to deal with indeterminism or lack of knowledge, since decision theory operates exclusively with criteria of rationality. 