The purpose of this paper is to clarify the role of value uncertainty and value instability in decision-making that concerns morally controversial issues. Value uncertainty and value instability are distinguished from moral uncertainty, and several types of value uncertainty and value instability are defined and discussed. The relations between value uncertainty and value instability are explored, and value uncertainty is illustrated with examples drawn from the social sciences, medicine and everyday life. Several types of factor producing value uncertainty and/or value (...) instability are then identified. They are grouped into three categories and discussed under the headings ‘value framing’, ‘ambivalence’ and ‘lack of self-knowledge’. The paper then discusses the role of value uncertainty in decision-making. The concluding remarks summarize what has been achieved and what remains to be done in this area. (shrink)