The above formula will apply, with the appropriate changes of emphasis, to buyers and sellers in an organized market, as well as to the parties to a simple transaction of barter. Two main empirical characteristics of the economic situation are suggested in putting the statement in just these terms. In the first place, the primary problem in such a situation is that of "exchange valuation," the fixation of a "subjective" (or better, a "personal") price ratio between what the agent wishes to acquire and whatever it is that he offers in exchange. The agent thus is engaged in determining what shall be the relative importance for himself of _two_ commodities or exchangeable goods. And in the second place these goods get their values determined together and in relation to each other, never singly and with a view to _subsequent_ comparison. These values when they have been determined will be measured in terms of marginal utility in accordance with familiar principles, but the marginal utilities that are to express the attained and accepted ratio at which exchange eventually takes place are not known quantities at all in the inception of the process of comparison. If these dogmatic statements seem to issue in hopeless paradox or worse, then let us not fear to face the paradox and fix its lines with all possible distinctness. Can a man decide to offer so much of one commodity for so much of another unless he _first_ has settled what each is worth to him in some intelligible terms or other? And is not this latter in point of fact the real decision--at all events clearly more than half the battle? Does not the exchange ratio to which one can agree "leap to the eyes," in fact, as soon as the absolute values in the case have been once isolated and given numerical expression?
In a single word we here join issue. For the comparison in such a case is _constructive comparison_, not a mechanical measuring of fixed magnitudes, as the above objection tacitly assumes. And constructive comparison is essentially a transitive or inductive operation whereby the agent moves from one level to another, altering his standard of living in some more or less important way, embarking upon a new interest, entering upon the formation of a new habit or upon a new accession of power or effectiveness--making or seeking to make, in short, some transformation in his environment and in himself that shall give his life as an entire system a changed tenor and perspective. The term "constructive comparison" is thus intended, among other things, to suggest that the process is in the nature of adventure, not calculation, and, on the other hand, that though adventurous it is not sheer hazard uncontrolled. And the motive dominant throughout the process--the economic motive in its constructive phase--is neither more nor less than a supposition, on the agent's part, that there may be forthcoming for him in the given case in hand just such an "epigenetic" development of new significance and value as we have found actual history to disclose as a normal result of economic innovation. It is the gist of hedonism, in economic theory as in its other expressions, that inevitably the agent's interests and motives are restricted in every case to the precise range and scope of his existing tendencies and desires; he can be provoked to act only by the hope of just those particular future pleasures or means of pleasure which the present constitution of his nature enables him to enjoy. Idealism assumes that the emergent new interest of the present was wrapped up or "implied," in some sense, in the interests of the remote and immediate past--interests of which the agent at the time could of course be but "imperfectly" aware. Such differences as one can discern between the two interpretations seem small indeed--like many others to which idealism has been wont to point in disparagement of the hedonistic world view. For in both philosophies the agent is without initiative and effect; he is in principle but the convergence of impersonal motive powers which it is, in the one view, absurdly futile, in the other misguidedly presumptuous, to try to alter or control.