The project addresses a discrepancy between two popular, yet seemingly incompatible views concerning the way we argue about values. On the one hand, in everyday conversations it is sometimes claimed that you cannot argue about personal preferences, a view reflected by proverbial slogans like “Every man to his taste”, “Tastes differ” or “One man’s meat is another man’s poison”. In the philosophical literature it has even been claimed that when two persons disagree about matters of taste they may both be right – each of them in his own way, on the basis of possibly different criteria. This position has been called ‘semantic relativism’ to set it apart from more obvious and less controversial positions about the context sensitivity of value predicates. On the other hand, hardly anybody would deny that you can and sometimes have to argue about values that go above and beyond personal taste. Value-laden questions like “How much welfare should the state provide?” or “How safe must this nuclear power plant be?” need to be discussed rationally, some moral philosophers would claim that they have objective answers, and they can in any case hardly just be a matter of personal taste. But how can we argue about such matters in a rational way, by providing reasons and well-formed justifications rather than merely trying to persuade others, if the basis of our assessments is values that one person may endorse and others reject? And how can the individual standpoints of participants in such a discourse be characterized insofar as values are concerned? Values seem to play a crucial role both in the assessment of how ‘good’ an argument is as well as in some types of arguments themselves.