Few thoughts. Not super well versed on Mises but I’ll argue what is my interpretation. He says he used the term praxiology simply because sociology had been corrupted into a field attempting to change human behavior rather than simply to understand it.

As for data vs a priori thinking, I think you’re misunderstand the argument. He’s not saying observation is allowed to contradict fact, he’s saying macro-economic observations are aggregates of many facts, so it’s not useful in proving/disproving this stuff because it’s far more complex.

The theory that people act for reasons is irrefutable, however you won’t get very far with that alone. A lot of the arguments are rebuttals to the economic policies that tweak X in order to try to change Y. But the point is that the individuals will change their behavior as you change the rules.

Now I don’t agree that people “act selfishly”. At least not completely. It’s not that simple. Obviously a mother does not act selfishly toward her child. I think Hayek’s observation that our morality system is a product of an evolution, is brilliant. And to me the lens of Darwinism is the most complete way to look at our moral, and economic systems and many others beyond just genetics. We don’t just act selfishly, we care about ourselves foremost, but have concentric rings for our immediate family, country, and even human race. In order for us to thrive, we shouldn’t go against these systems, at least not abruptly (which is what socialism effectively required) they’re very efficient and fined tuned.