We began with three propositions: that people have a right not to be treated as mere means to the ends of others, that a woman who voluntarily becomes pregnant nevertheless has the right to an abortion, and that a woman who voluntarily gives birth does not have a right to abandon her child until she finds a substitute caretaker. These propositions initially seemed inconsistent, for the prohibition on treating others as mere means appeared to rule out the possibility of positive rights, thus making it impossible to countenance the right to abort or the right not to be abandoned (both of which, it was argued, are positive in form).
But we have seen that the prohibition on treating people as mere means to the ends of others is best understood as ruling out basic positive rights while permitting derivative ones. Since a willing mother is responsible for bringing her child into the world in the first place, she cannot abandon it without violating its negative right not to be killed, and so such a child has a derivative positive right not to be abandoned. A pregnant woman, on the other hand, has a negative right not to have her body invaded, and from this negative right derives a positive right to abort her fetus, so long as doing so is not disproportionate to the seriousness of the threat (as it is not in the case of involuntary pregnancy, or of pregnancy which has become involuntary). Therefore, far from being in conflict, propositions (1), (2), and (3) have been shown to be in harmony with one another, the latter two being plausibly grounded in the first. Insofar as we have reason to accept (1), then, we have reason to accept (2) and (3). Moreover, we have seen that a proper understanding of (1) allows us to embed (2) and (3) in a larger moral perspective in which the limits of compulsory altruism are firmly drawn: enforceable rights to the use or assistance of others may be allowed into the moral domain only if they are “sponsored” by some negative right. Every putative positive right must find such a sponsor, or perish.