> There's a difference economically, because the derivative of marginal utility with respect to income is (generally) negative. In other words, utility is conca

> There's a difference economically, because the derivative of marginal utility with respect to income is (generally) negative. In other words, utility is concave with respect to the origin[0]. Sure.. many economic models make this simplifying assumption. But each man defines his own utility functions, by their very nature.