  This may be one area then where the differences between different possible organ sale systems are relevant. For it is not wildly implausible to posit the existence of a duty to donate one's organs for posthumous transplantation. Indeed, this view is not confined to utilitarian bioethicists, with even the Church of England stating in 2007 that (posthumous) organ donation is a Christian duty (BBC News Online 2007). Thus there may well be a valid altruism argument against a system in which people sell rights to their body after death: the argument being that they should donate them anyway without expecting payment. This style of argument looks less promising, though, when looking at non-directed living kidney donation (to strangers). Here, I suspect most of us want to say that becoming such a donor is heroic and supererogatory, not a moral obligation, and so the altruism argument does not engage. Another interesting example is blood (from living donors). In many countries, there is a widespread view that people ought to do this freely and (if this view is correct) this could underpin an altruism argument against paying for blood: the claim being that people ought not to be paid for that which they have an obligation freely to give.