This is a continuation on Did Mises Contradict Himself?
A Popperian critique about praxeology is quite simple: it does not account for falsification, thus it cannot be considered scientific. That’s it. See, Popperians don’t even bother criticizing praxeology in itself, they don’t criticize whether or not there is such thing as purposeful action, whether people in the marketplace are always rational, or whether a purely logical approach was a good place to start with explaining economic theory. What they rather look at is the structure of praxeology and whether or not it took account for the falsification of that structure because they realize that there could never be a structure that is perfect, since humans are not perfect beings.
Now Mises had a similar view. He thought that economic theory could never be perfect because we have limits that prevent us from being perfect. An economic theory that would satisfy us today may be discarded in the future and replaced by a better theory. So in a sense, economics was an evolutionary science in which theories had to account for change since theory was never perfect.
Now we can see that they both accept the fact that economic theories have to account for change since it is impossible to have a perfect structure where theory could rest on. But Mises makes this obvious contradiction in saying that the structure of praxeology could not be falsified.
Now one can say that praxeology does account for falsification inside its framework, that is, one can find falsifications due to illogical implications in the deduction process, but that is not a satisfactory answer because the contradiction does not rest on whether a structure takes account for falsification inside its framework, rather it rests on whether the structure itself can be falsified because remember there could never be a perfect structure, that is, a structure cannot just claim it can never be falsified, because in doing so, you have to admit that your mind just created a perfect system, which is impossible.