In praxeology, methodological dualism is an epistemological position which states that it is necessary ─ based on our current state of knowledge and understanding ─ to use a different method in analysing the actions of human beings than the methods of the natural sciences (such as physics, chemistry, physiology, etc.).
[1] This position is based on the presupposition that humans differ radically from other objects in the external world.
[3] Ludwig von Mises' insistence on methodological dualism was a reaction against “the ‘methodological monism’ preached by behaviorists and positivists who [saw] no basic reason to approach human behavior and social phenomena differently from the way natural scientists approach molecular behavior and physical phenomena.”[4] Mises states that the sciences of human action deal with ends and means, with volition, with meaning and understanding, with “thoughts, ideas, and judgments of value”.
[5] Thus, these mental phenomena occupy a central position in the sciences of human action for, as Mises argues, “acts of choosing are determined by thoughts and ideas.”[6] In arguing for methodological dualism, Mises states because the natural sciences have not yet determined “how definite external events […] produce within the human mind definite ideas, value judgments, and volitions”,[7] this ignorance splits our knowledge into two distinct fields, the “realm of external events” on the one hand, and the “realm of human thought and action” on the other.
Thus Mises’ conception of the sciences of human action ─ i.e. praxeology and thymology ─ is based on this methodological dualism.