Self-Defense and Giving Rise to Cost: On Innocent Bystanders, Threats, Obstructors, and Obstacles, and the Permissibility to Harm Them

Philosophers have had trouble defending the common sense view that it is permissible to impose significant cost on an innocent person who is about to harm you to prevent the harm from occurring. In this paper, I argue that such harm can be justified if one pays attention to the moral significance of imposing a cost on others. The constraint against harming people who give rise to cost by their presence or movements is weaker than the constraint against harming bystanders. Moreover, I argue that people who give rise to cost have a duty to take on some of that cost to help protect the person under threat.