 Mary’s behaviour seems morally wrong. Utilitarians have a simple account of why Mary’s behaviour is wrong, as she brings about less human happiness than she could have done. Yet it seems that contractualism cannot capture this intuition. Consider a principle permitting Mary’s behaviour. If Mary’s behaviour is wrong, then this principle must be one that someone can reasonably reject. But who? Not the Winter Child—because he would otherwise never have existed at all. And not the Summer Child—because he doesn’t exist.