>To see an even strong example of this behavior, consider some action that is even more offensive to the common sensibilities that killing someone, such as certain forms of child abuse. Now imagine a situation where by doing that to one child, you can stop it being done to N others. (Worry not about the details of how such a situations could occur, I'm sure some creative individual could find a back story.)

Use this thing: http://www.scp-wiki.net/scp-231