The doctrine that there is a definite, unchanging sum of economic values, therefore, cannot, in my judgment, be maintained. And yet, it must be conceded, there is a substantial element of truth in Professor Seligman's contention. At a given time, or through a considerable period, assuming social conditions to change slowly, there are fairly definite amounts of social energy, both of production and of control over production (value-giving energy). The surface fact here is that men have definite incomes. If this energy is disposed of in one way, it cannot be disposed of in another. If men elect to have one good, they must dispense with something else. And in using their control over social forces to increase the value of one good, they must refrain from using it to increase the value of another. In the long run, these quantities are subject to change. At a given moment, a sudden disturbance may radically change them. But, as a statement of tendency, Professor Seligman's doctrine must be admitted. Professor Seligman's view differs from that of Professor Clark simply in that it adds an element. On its logical side, it conceives value in the same way. Value is a quality, with degrees, i.e., a quantity. This quantity in a particular good is an absolute fraction of an absolute quantity. It is not changed merely in consequence of being compared with some other good--it remains the same, regardless of what price-ratio it is put into. On its formal and logical side, therefore, Professor Seligman's concept is to be classed with that of Professor Clark--with which, as indicated in chapter II, I am in hearty accord, in so far as the issues raised in that chapter are concerned. FOOTNOTES: [183] _Principles_, 1905, p. 174. [184] _Economic Interpretation of History_, _passim_. [185] _Principles_, p. 175. [186] _Ibid._, pp. 147-48. [187] It might be possible to put the argument into terms which would give an analogical meaning to "social utility" and "social cost." The diagram representing the intersection of the demand curve and the supply curve, fixing price, may be taken equally well to represent the balance of social forces which lies back of the market phenomena in the case of a given commodity. The demand curve might then be called a "social utility" curve, and the supply curve a "social cost" curve, if only it be remembered that cost and utility here have only a vague, analogical meaning, and cover up a host of factors which, while they fall conveniently into two opposing groups, like the individual's "cost" and "utility," are yet much more than the latter. But they are really so very much more than the latter, that it seems to me misleading to continue the use of the terms, utility and cost, when the associations of these terms in economic theory are remembered. The tendency would be to make the student feel that value depends on two abstract phases of social-mental life, instead of being an outcome of the organic whole. [188] Pp. 342-43.