Austrian econ conundrum: If economic principles are a priori, still the question of which principle explains an observed phenomenon can only be settled by empirical work, right? But if so, doesn't the empirical justification always just affirm the consequent?
I.e. If a priori economic principle P is at work, then we should expect to see effect Q; in the real world, we see effect Q, therefore we infer that principle P is at work?
That's logically invalid.
But it gets worse, because Q isn't even a necessary (let alone sufficient) condition for P in the real world. No: P might really be at work, and yet some other principle, P', is also at work, and it cancels out the otherwise expected outcome Q. If we fail to find Q, P still could be at work, and praxeology thus has zero necessary connection to the phenomenal world.
So, what I am really questioning here is its ability to inform us about or explain the real world. So imagine that there is a housing shortage, not a thing that cannot happen, but one that actually is happening. How would we know what was causing it? That's where things get difficult here: not in how we rule out the impossible, but in how we account for the actual.