An error in Frank Knight’s philosophy of science caused an error in his science, and thus he was unable to see the evolutionary potential of Ludwig von Mises’s economic science. In doing so, Knight unwittingly promoted a view of economic science that undermines the scientific import of his own book Risk, Uncertainty, and Profit and the philosophical wisdom of Mises’s Freedom and Reform. Untangling this Knightian knot will be part of our rational reconstruction of the possible future scientific and practical path cleared for us by Mises’s Human Action.