This article takes issue with the widespread assumption that students' socioscientific decisions ought to be evidence based. On the basis of a careful conceptual analysis, it is argued that it is misleading to think in terms of evidence in socioscientific decision making because such decision making is a process of deliberation in which persons distribute relative weights to multifarious and incommensurate factors--a process, that is, in which scientific evidence has no privileged role. Accordingly, science educators ought to focus on the quality with which students discuss the relative weights of different considerations about a socioscientific issue.