The Laws of Belief—Ranking Theory and its Philosophical Applications
Frank Zenker · The Philosophical Quarterly · 2014
Reaching print at a time when the Laplacian conception of probability is so popular that talk of ‘degrees of belief’ appears almost completely normal, Wolfgang Spohn's masterwork might raise eyebrows by devoting 600 closely printed pages to ranking theory. Yet the book is one of great gravity in more than the literal sense. As part of the surge in research on formal models for rational belief revision that began in the 1980s, Spohn developed a broadly Baconian approach to probability under the term ‘ordinal selection function’. Now more commonly called a ‘ranking function’, this remains a key representational device for constructing an idealized normative account of why doxastic states change. Ranking functions represent both a doxastic system's prior state and the posterior state that arises in response to sensory or other relatively firm evidence. At any rate, such states are said to be adequately characterized by this formal device. Ranking theory thus provides a general description for prior–posterior transitions among consistent and deductively closed sets of belief, while leaving the initial state largely unconstrained.