In the last chapter, I explained basic features of tort liability in terms of the idea of reciprocity. In this one, I explicate the conception of responsibility implicit in that idea. Any account of responsibility limits its purview to the sorts of beings who can be responsible, who have such capacities as are required to moderate their activities. An account of why certain changes in holdings must be undone can only apply to agents who are capable of moderating their activities in light of the interests of others. The capacities that are relevant to tort liability are thus themselves identified in terms of reciprocity and fair terms of interaction. As I suggested in discussing Vaughan v. Menlove, those who are free to exercise their liberty must take responsibility for the costs they impose on others, even if on particular occasions they are unable to live up to the standard of care.

Perhaps the most important of the capacities that is requisite to tort liability is the capacity for foresight. As a result, it is the central focus of my discussion. Negligence liability is ordinarily limited to those consequences of wrongdoing that are foreseeable. If an injury is not foreseeable, it is not compensable. The requirement that injuries be foreseeable may look like a competing principle, in tension with the risk rule and the idea of reasonableness, because foresight appears to be an epistemic feature, definable apart from any question of fair terms of interaction.