Hobbes's central insight about ethics was that it should not be understood to require that we make ourselves a prey for others. It is this insight that both varieties of contractarianism [Hobbesian and Kantian] respect. Consider a relationship between two human beings that exists for reasons of either love or duty; let us also suppose that it is a relationship that can be instrumentally valuable to both parties. In order for that relationship to receive our full moral endorsement, we must (...) ask whether either party uses the duty or the love connecting them in a way that affects the other party's ability to realize the instrumental value from that relationship. To be sure, good marriages and good friendships ought not to be centrally concerned with the question of justice, but they must also be, at the very least, relationships in which love or duty are not manipulated by either party in order to use the other party to her detriment. (shrink)