Mill does not pretend that this person actually exists; but that the tendency of things is as though he did exist; and that it is most easy to assume his existence, and after that recognize the qualifications which other parts of human nature require us to put in, just as in mechanics we calculate what would happen if surfaces were smooth, and then allow for friction afterwards.
Ruskin’s criticisms are not always fair. He writes:
“Political Economy, being a science of wealth, must be a science respecting human capacities and dispositions. But moral considerations have nothing to do with political economy (says Mill). Therefore, moral considerations have nothing to do with human capacities and dispositions.”[61]
Perhaps the logical fallacy is not very obvious, but it is there. Human capacities and dispositions touch moral considerations on one side, and they touch political economy on the other. But these two need not therefore be connected. Because a man has two relations, as a citizen and as a father, and because the state does not bring up his children, and the two relations are separate, we must not argue that the man has nothing to do with his family, because the state, with which he is also connected, has nothing to do with it. All this wrong criticism was produced by the obvious remark of Mill, that the ethical character of a taste for diamonds is not the economist’s affair.
It is only as a first approximation, then, that economics postulates the monster known as the economic man; cold, calculating, well informed, shrewd, selfish with the unthinking uniformity of a machine. It is perhaps clearer to say that it can take account only of such motives as are sufficiently regular and predictable to be worth so much in money. Some unselfish actions are of that kind, such as a man’s service to his children, or if he be a Highlander to his third cousin; and we can predict certain of his regular subscriptions. The Law of Supply and Demand applies to ministers and missionaries and hospital nurses, though their payment is all from charitable gifts. To some extent the Charity Fund is a steady sum in any nation. It could be predicted that when the national War Fund was absorbing large sums, other charities, particularly London charities, would suffer; and such has been the case. The same phenomenon occurred to a less degree when General Booth was raising his Darkest England Fund. Here is a charitable motive steady enough to be measurable.