Douglas has argued that if values were accorded a ‘direct’ role during the ‘internal’ phases of science, this would amount to ‘wishful thinking’ in place of evidence. This paper draws on two claims that jointly threaten this position. First, building a cogent ethical case in favour of a claim about what ought to happen is not a simple matter of saying what one wishes were true; a good ethical case has a kind of discipline to it. Second, some theorists have argued that scientists do and should defend ‘mixed hypotheses’; that is, hypotheses that implicate both factual and evaluative content.