How can we justify the superior rewards of that scarcity which is not due to unusual costs of any sort, but merely to restricted opportunity? So far as society is concerned, the answer is simple: the practice pays. As to the possessors of the rarer kinds of ability, they are in about the same ethical position as those persons whose superior productivity is derived entirely from superior native endowment. In both cases the unusual rewards are due to factors outside the control of the recipients; to advantages which they themselves have not brought into existence. In the former case the decisive factor and advantage is opportunity; in the latter it is a gift of the Creator. Now we have seen that this sort of productivity cannot be proved to be immoral as a canon of distribution; consequently the same statement will hold good of this sort of scarcity. _The Canon of Human Welfare_ We say "human" welfare rather than "social" welfare, in order to make clear the fact that this canon considers the well being of men not only as a social group, but also as individuals. It includes and summarises all that is ethically and socially feasible in the five canons already reviewed. It takes account of equality, inasmuch as it regards all men as persons, as subjects of rights; and of needs, inasmuch as it awards to all the necessary participants in the industrial system at least that amount of remuneration which will meet the elementary demands of decent living and self development. It is governed by efforts and sacrifices, at least in so far as they are reflected in productivity and scarcity; and by productivity and scarcity to whatever extent is necessary in order to produce the maximum net results. It would give to every producer sufficient remuneration to evoke his greatest net contribution to the productive process. Greatest "net" contribution; for a man's _absolute_ maximum product may not always be worth the required price. For example: a man who for a salary of 2500 dollars turns out a product valued at 3000 dollars, should not be given 3000 dollars in order to induce him to bring forth a product worth 3300 dollars. In this case a salary of 2500 dollars evokes the maximum net product, and represents the reward which would be assigned by the canon of human welfare. Once the vital needs of the individual have been safeguarded, the supreme guide of the canon of human welfare is the principle of maximum net results, or the greatest product at the lowest cost.