The fact is that there are a number of other systems of thought that are (allegedly) derived by deduction from universally true axioms. How do we choose between such systems? For example, Marxists like M. Hollis and E. J. Nell have propounded a system using deduction from (allegedly) universally true axioms in their book Rational Economic Man (1975). Their system is the antithesis of Mises’ Austrian economics, but supposedly arrives at laws which are universally true. In other words, when competing praxeological systems are encountered, what method is available to the Austrian praxeologist to choose between them?
Because this is a philosophical question, I asked my colleague David Gordon who supplied the following answer:
Thanks for this excellent question. If true premises led to contradictory conclusions, we would really be in trouble! Fortunately, your student has I think read Hollis and Nell wrongly. They do indeed defend economic laws as necessary truths,and Hans Hoppe has cited them in support of his own views on methodology. They don’t claim that their analysis of capitalism is based on deductions from self-evident axioms, though. Rather, they incorporate empirical claims about capitalism into their work.