Abstract
The principle of exchange seems to be limited in its application, and it cannot serve as a link between utilitarianism and the idea of a market for interpersonal relations. Our preferences concern the inner states of other people as well as their overt behavior. The neglect of this aspect of our preferences is a result of the coupling of utilitarianism with behaviorism. The problem is thus behaviorism, not consequentialism.
It might be argued that commensurability is wrong because it sanctions impure practices - aside from any principle of exchange. In reply, it may be argued that the principle of purity is an intuitive one, which must be justified at a higher level. At the intuitive level, the purity principle competes with the view that practices are in some cases too pure already, and that blind purity cannot be maintained without educational deception.
The apparent difficulty of making tradeoffs among different kinds of consequences is a problem in practice, not a problem in principle. The difficulty may indeed justify certain prescriptive rules, but a blanket prohibition against impure practices would seem to require considerable defense.