During the introduction, Mises makes a note that the first use of the term Praxeology occurred first in a work by Alfred Espinas, who had been a positivist before becoming a realist.
So, I translated the part being referred to: Alfred Espinas. Les Origines de la Technologie. // Revue Philosophique de la France et de l'Étranger. T. 30 (Julliet à December 1890). p. 114-116; I think I'll translate the whole article later, it is rather interesting from what I've skimmed through.Dive into the definition