The old subjectivism limits the freedom of the economist to use his own value judgments. Mises discovered the new subjectivism by trying to understand the method of the old subjectivists. A deeper examination shows that, by rejecting the classical notion of natural law, they were studying a class of phenomena that was fundamentally different from that of the natural sciences. We can call this class distinctly human action . We use this term to distinguish this class from other characteristics of human beings and non-humans.
Human beings share many characteristics with other objects.
They occupy space and their movements can be observed and measured. They also share characteristics with other animals. They have sensations, instincts, the want for food and comforts, and imprinted behavior, some of which is suitable for helping to satisfying wants. Distinctly human action refers to precisely those characteristics that human beings do not have in common with other physical objects and animals. But the fundamental class of phenomena that they had in mind was action.