In 1949, the first year of Harry S. Truman's only elective presidential term, three things happened that were of huge importance ... at least to me. Ludwig von Mises (1881-1973) published Human Action. Gilbert Ryle (1900-1976) published The Concept of Mind. And, oh yeah, I was born. The connection here is that Mises's and Ryle's books are two of the most influential things I have ever read. What's also interesting is what else the books have in common. Human Action sets out the logical structure of all purposeful action as well as its socioeconomic implications. Mises called the study of...