This paper considers the question whether plaintiffs, whose claims pose an important common issue, and are thought to be unlikely to prevail on this issue, should be permitted to maintain a class action in which this issue will be resolved or be required to litigate their claims in individual suits. The paper takes as its point of departure an opinion of Judge Richard Posner offering a novel and complex theoretical justification for requiring plaintiffs to proceed individually. This justification rests on ideas with respect to how claims thought to be unlikely to prevail should be viewed, how the risks created by legal uncertainty should be distributed and how decisionmaking should be structured to take account of the different verdicts various juries might render with respect to identical cases. These ideas have very general and important implications. The paper concludes that Judge Posner's opinion suppresses important issues implicated by his analysis and that consideration of these issues leads to a view much more inclined to permit the class action to go forward than the one advanced by Judge Posner.