Another, related problem for which Frege’s distinctions might seem to offer no help concerns the epistemic status of thymology, the “knowledge of human valuations and volitions.” Thymological insight is crucial in order to be able to apply praxeology to actual cases; for purposes of understanding the economic activity of a given society, it is useless to know the laws of, e.g., monetary theory if one cannot determine whether the society has money or, if it does, which items serve as money; but an item’s status as money depends on the beliefs and desires of that society’s inhabitants (their willingness to accept it as a medium of exchange, for example). As F. A. Hayek notes:
That the objects of economic activity cannot be defined in objective terms but only with reference to a human purpose goes without saying. Neither a “commodity” or an “economic good,” nor “food” or “money,” can be defined in physical terms. ... Economic theory has nothing to say about the little round disks of metal as which an objective or materialist view might try to define money. ... Nor could we distinguish in physical terms whether two men barter or exchange or whether they are playing some game or performing some ritual. Unless we can understand what the acting people mean by their actions any attempt to explain them, that is, to subsume them under rules ... is bound to fail.17
But that means that while the laws of praxeology belong to the third realm rather than to the inner realm, we cannot apply those laws without knowledge of the inner realm, and in particular of the inner realms of other people. Yet if Frege is right, those inner realms are inaccessibly private; as we’ve seen, Frege holds that “no-one has someone else’s presentation but only his own,” and therefore “no-one knows how far his presentation – e.g. that of red – agrees with that of someone else.”18 Mises of course holds that we know other people’s beliefs and desires via the verstehen method of Dilthey and Collingwood – entering imaginatively into others’ behaviour so as to understand it from the inside; but
17 Friedrich A. Hayek, The Counter-Revolution of Science: Studies on the Abuse of Reason (Liberty Fund, 1979), pp. 52-53.
18 Frege, Review of Husserl, op. cit., p. 325.
R. T. Long – Wittgenstein, Praxeology, and Frege’s Three Realms – p. 10