Praxeology is not reasoning completely isolated from all emirical facts

There is a common misconception among people that praxeology does not take into account any empirical content whatsoever. To the contrary, praxeology takes empirical facts as given and reasons from established empirical facts. All empirical economic facts are historical. Therefore these facts are established the same way historians would establish them.

Mises explains this in The Ultimate Foundation of Economic Science page 44-45:

“Into the chain of praxeological reasoning the praxeologist introduces certain assumptions concerning the conditions of the environment in which an action takes place. Then he tries to find out how these special conditions affect the result to which his reasoning must lead. The question whether or not the real conditions of the external world correspond to these assumptions is to be answered by experience. But if the answer is in the affirmative, all the conclusions drawn by logically correct praxeological reasoning strictly describe what is going on in reality.”

What people conflate is Mises’s assertion about the impossibility of empirically testing these conclusions established by praxelogical reasoning, like they would do in other sciences like physics. This doesn’t mean the person is infallible; their reasoning could be incorrect. However given the reasoning is correct, the conclusions must necessarily follow.