standard for correct thinking.) I’ve discussed Wittgenstein’s arguments in detail elsewhere and so will not go into them again here, except to note that one of the chief examples he uses to illustrate his argument is an economic example, whose point – though Wittgenstein does not word it this way – is to show that nothing counts as an economic transaction unless it follows the laws of economics.
Wittgenstein was interested in the economic example not for its own sake but simply as a useful analogy to the case of logic; but in showing the impossibility of contra-logical thought, Wittgenstein has incidentally shown the impossibility of contra-praxeological action as well, and so has disposed of the spectre of normative polylogism, thereby vindicating Mises’ claim that the human mind can neither conceive A to be non-A (logical deviance) nor prefer both A to B and B to A (praxeological deviance).
In showing that logic constrains not just what can be correctly thought but what can be thought at all, however, Wittgenstein extends the realm of logical necessity from the third realm to the inner realm, and thus blurs the boundary between those two realms. In this respect he might seem to be undoing what Frege had accomplished; still, what Wittgenstein is doing is Fregean in spirit – for Wittgenstein’s blurring seeks not to reduce the third realm to the inner realm, but on the contrary to exalt the inner realm by taking it up, at least in part, into the third realm, and so this blurring is still in its way an anti-psychologistic project. Stanley Cavell perhaps puts the point most illuminatingly, albeit somewhat paradoxically, when he writes:
We know of the efforts of such philosophers as Frege and Husserl to undo the “psychologizing” of logic (like Kant’s undoing Hume’s psychologizing of knowledge): now, the shortest way I might describe such a book as [Wittgenstein’s] Philosophical Investigations is to say that it attempts to undo the psychologizing of psychology, to show the necessity controlling our application of psychological and behavioural categories; even, one could say, show the necessities in human action and
R. T. Long – Wittgenstein, Praxeology, and Frege’s Three Realms – p. 12