 It might seem as though the idea of incommensurable alternatives does not really make sense. For if the value of an alternative (to a particular agent) is neither higher nor lower than the value of another alternative, then the values of the two alternatives must, it seems, be equal. But this assumes that there is a common measure that one can use to express and rank the value of every alternative; and, if there are incommensurable alternatives, then this assumption is mistaken.