Menger's Proto-Misesian Methodology
I was reading Jeffrey Herbener's incredibly educational introduction to The Meaning of Ludwig von Mises (which he also edited), and came across a quote he cites from Carl Menger's Investigations into the Method of the Social Sciences that makes abundantly clear how close Menger and Mises were to each other on method, contrary to the claims of Max Keiser and John Aziz.
"Among economists the opinion often prevails that the empirical laws, 'because they are based on experience,' offer better guarantees of truth than those results of exact research which are obtained, as is assumed, only deductively from a priori axioms ...
Testing the exact theory of economy by the full empirical method is simply a methodological absurdity, a failure to recognize the bases and presuppositions of exact research. At the same time it is a failure to recognize the particular aims which the exact sciences serve. To want to test the pure theory of economy by experience in its full reality is a process analogous to that of the mathematician who wants to correct the principles of geometry by measuring real objects. . . .
An empirical law lacks the guarantee of absolute validity a priori, i.e., simply according to its methodological presuppositions ...
To want to transfer [the empirical method] to the results of exact research is, however, an absurdity, a failure to recognize the important difference between exact and realistic research. To combat this is the chief task of the preceding investigations."
Also see David Gordon on this topic.