Necessity, moral liability, and defensive harm

A person who is liable to defensive harm has forfeited his rights against the imposition of the harm, and so is not wronged if that harm is imposed. A number of philosophers, most notably Jeff McMahan, argue for an instrumental account of liability, whereby a person is liable to defensive harm when he is either morally or culpably responsible for an unjust threat of harm to others, and when the imposition of defensive harm is necessary to avert the threatened unjust harm. Others may favour a purely noninstrumental account of liability: one that looks only to the past behaviour of the potentially liable person. We argue that both views are vulnerable to serious objections. Instead we develop and defend a new view of liability to defensive harm: the pluralist account. The pluralist account states that liability to defensive harm has at least two bases. First, if an attacker is morally or culpably responsible for an unjust attack then he has forfeited what we call his agency right, and in doing so he has made himself partially liable to defensive harm. Whether the attacker is fully liable to defensive harm depends, however, on whether the imposition of defensive harm would infringe a different right held by the attacker: his humanitarian right. Humanitarian rights are rights to be provided with urgently needed resources or to be protected from serious harms when others can do so at reasonably low cost. We argue the pluralist account avoids the objections to which the instrumental and noninstrumental views are vulnerable, coheres with our intuitive reactions in a wide range of cases, and sheds new light on the way different rights combine to determine a person's liability to suffer harm. © Springer 2012.