Philosophy and Public Affairs, vol. 1, no. 1 (Spring 1972), pp. 229-243 [revised edition]
"It might be thought that this argument has an absurd consequence. Since the situation appears to be that very few people are likely to give substantial amounts, it follows that I and everyone else in similar circumstances ought to give as much as possible, that is, at least up to the point at which by giving more one would begin to cause serious suffering for oneself and one's dependents - perhaps even beyond this point to the point of marginal utility, at which by giving more one would cause oneself and one's dependents as much suffering as one would prevent in Bengal. If everyone does this, however, there will be more than can be used for the benefit of the refugees, and some of the sacrifice will have been unnecessary. Thus, if everyone does what he ought to do, the result will not be as good as it would be if everyone did a little less than he ought to do, or if only some do all that they ought to do."