This article is an attempt to defend Scanlon's contractualism against the so-called aggregation problems. Scanlon's contractualism attempts to make sense of right and wrong in terms of principles which no one could reasonably reject. These principles are a function of what kind personal objections persons can make to alternative sets of moral principles. Because of this, it has been argued that contractualism is unable to account for how groups of different sizes are to be treated. In this article, I argue (...) that contactualism, even if with its focus on personal burdens, can come to plausible conclusions in the group cases. (shrink)