Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Linguistics and Philosophy, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 152-155).Some actions are identity affecting, they affect who will exist in the future. Explaining how identity affecting actions can be wrong has been thought to pose a problem, the Non-Identity Problem. The problem is that an identity affecting action could be wrong even though no one would be harmed if it were performed. If no one would be harmed, how can we explain why it is wrong? The Non-Identity Problem assumes that someone is harmed by an action only if someone would be worse-off if it were performed than they would be if it were not. I defend this assumption, ...