Epistemological duality

In this way, von Mises and Hoppe have not only repaired the rationalist paradigm but also created a grand system that presents a comprehensive axiomatic-deductive system of science. Hoppe calls the supporters of this system radical Austrians in contradistinction to those Austrians who do not want to accept the twin axioms of action and argumentation.

The Radical Austrian grand system starts from praxeological epistemology and first proceeds to logic. Since knowledge is a category of action it becomes clear that the laws of logic are practical affairs that are presupposed in both action and argumentation axiom. The laws of logic fits into human reality not by coincidence but because thought and action develop together anchored in physical reality.

When one understands that knowledge as displayed in argumentation is a peculiar category of action, the validity of the perennial rationalist claim that the laws of logic—beginning here with the most fundamental ones of propositional logic and of Junctors (“and,” “or,” “if-then,” “not”) and Quantors (“there is,” “all,” “some”)—are a priori true propositions about reality and not mere verbal stipulations regarding the transformation rules of arbitrarily chosen signs, as empiricist-formalists would have it, becomes clear. They are as much laws of thinking as of reality because they are laws that have their ultimate foundation in action and can not be undone by any actor. …

In each and every action, an actor identifies some specific situation and categorizes it one way rather than another in order to be able to make a choice. It is this which ultimately explains the structure of even the most elementary propositions (like “Socrates is a man”) as consisting of a proper name or some identifying expression for the naming or identifying of something and a predicate to assert or deny some specific property of the named or identified object. It is this which explains the cornerstones of logic: the laws of identity and contradiction. And it is this universal feature of action and choosing which also explains our understanding of the categories “there is,” “all,” “some,” “and,” “or,” “if-then,” and “not.”.⁶

Hoppe continues his deduction also into arithmetic and geometry. In short, action axiom is the foundation of all logical reasoning. After all, thinking is action too. Thus, praxeology is the foundation of logic and therefore through protophysics also the foundation of natural science.

Furthermore, action axiom is also connected to truth through the argumentation axiom. Argumentation is action too. It is a peculiar sort of action that raises the idea of truth. Action and argumentation create a sort of interconnected praxeological-epistemological duality that creates the foundation not only of epistemology but of all sciences.

This duality conforms well to practical common sense. After all, an acting individual is always faced with the problem of evaluating his own situation. He needs knowledge. Therefore he distinguishes himself from the situational surroundings. This already presupposes the law of identity and contradiction, i.e. the difference between the subject and object. Then he makes a plan how to improve some aspects of his situation. All this already presupposes that he is using logic and making propositions, i.e. sort of arguing with himself over his own situation by asking relevant questions about his situation and answering accordingly. This raises the idea of truth that is manifested in the practical validity and application of knowledge in successful plans for action.

Knowledge is thus not a pure mental speculation and dreaming but a mental ingredient of all action, i.e. a category of action. This is why a priori knowledge embodied in argumentation is ultimately based on action and constrained by the framework of action categories. Argumentation is the other side of the action coin and the axioms of action and argumentation are interwoven strands of a priori knowledge.⁷