The science or general theory of (conscious or purposeful) human action.
Ludwig von Mises defines action as "the manifestation of a man's will." Accordingly, he considers the use of the adjectives "conscious or purposeful" to be redundant. Praxeology is a manifestation of the human mind and deals with the actions open to men for the attainment of their chosen ends. Praxeology starts from the a priori category of action and then develops the full implications of such action. Praxeology aims at knowledge valid for all instances in which the conditions exactly correspond to those implied in its assumptions and inferences. Its statements and propositions are not derived from experience, but are antecedent to any comprehension of historical facts.
Praxeology, more than just being a fancy term, plays an important role in the study of economics and free markets because the preference of individuals becomes more evident by how people act rather than what they say. This idea underscores the importance of allowing individuals to operate independently and voluntarily and free markets.
I plan to expand on the idea of praxeology as I develop this website in the future.