Nonidentity Problem

The nonidentity problem arises when an action affects which person exists rather than merely changing an existing person’s welfare. Someone with a life worth living might not have existed under the alternative decision. That makes a familiar comparative account of harm difficult to apply.

The problem depends on a specific counterfactual: the affected individual would not have existed if the alternative action had been chosen. Ordinary examples of worsening an existing person’s prospects do not have that structure. Keeping identity fixed makes comparative harm straightforward; changing identity complicates it. Yet a choice can still leave people below a defensible standard. The philosophical pressure is to explain that judgment without assuming a better version of the same individual existed in the alternative.

Imagine choosing a long-term development policy that changes where people live and whom they meet. Decades later, a different policy would have produced different children. An affected person cannot simply compare their life with their own better life under that alternative.

The problem challenges the claim that every wrong must make a particular person worse off. Possible responses appeal to rights, noncomparative harms, duties to provide decent conditions, or the value of outcomes. Each response needs care: explaining a wrong should not imply that the people who now exist lack value or should regret existing.

An invented planning decision changes migration patterns and eventually which children are born. The resulting children inherit poor public infrastructure, although their lives are worth living. Instead of asking only whether they are worse off than they otherwise would have been, ask whether the planners fulfilled a duty to provide decent conditions. That proposal may explain the wrong, but it needs a defended standard and an account of how demanding the duty is for present people.