More precisely: the world is full of puzzles that we do not understand. Austrians think those analytical propositions are necessary (though not sufficient) for good explanations of those puzzles. What sorts of arguments and evidence are needed to offer persuasive accounts of those puzzles in ways that render them no longer puzzling? Different puzzles will require different propositions, which will require different methods and empirical evidence to render them intelligible.
One way to put this argument is that what makes a piece of economics “Austrian” is not so much the particular method that is employed, or even the philosophy of science that guides the investigation (as if every economist has thought about this), rather it is the substantive propositions about the economy that are being deployed and/or argued for in that piece of work.
UPDATE: the third piece is now up.