  Kidneys may then be importantly different from (say) blood. For if there is no substantial system of free donation in place, then free donation cannot be undermined by permitting sale. But if an almost adequate system of free donation does exist (as, in many countries, it does with blood) then there is a serious possibility of its being undermined. Thus, the argument which says that what is wrong with sale is that free donation would be undermined might well work for blood, even if it does not for kidneys. The same might be true of the arguments in favour of an altruistic blood system proposed by Titmuss and others. Perhaps the voluntary blood donation system (and indeed a voluntary posthumous organ donation system) can be used as a method of encouraging a valuable culture of altruism, but this is much less likely to work in the case of living organ donation (Archard 2002; Campbell 2009; Titmuss 1997).