Johannes von Kries’s Principien: A Brief Guide for the Perplexed

This paper has the aim of making Johannes von Kries’s masterpiece, Die Principien der Wahrscheinlichkeitsrechnung of 1886, a little more accessible to the modern reader in three modest ways: first, it discusses the historical background to the book (in particular, what Keynes later termed the “principle of indifference”); next, it summarizes the basic elements of von Kries’s approach (in particular, his “Principle of the Spielraum”); and finally, it examines the so-called “principle of cogent reason” with which von Kries’s name is often identified in the English literature.