This paper argues that non-identity actions are wrong because they _cause_ harm to people. While non-identity actions also typically benefit people, failure to act would similarly benefit someone, so considerations of benefit are ineligible to justify the harm. However, in some non-identity cases, failure to act would not benefit anyone: cases where one is choosing whether to procreate at all. These are the _hard_ non-identity cases. Not all "different-number" cases are hard. In some cases, we don't know whether acting would (...) result in more or fewer people; this paper argues that this _epistemic_ factor makes acting in these cases wrong. (shrink)