Epistemology Probabilized

  • Richard Jeffrey
Part of the Studies in Fuzziness and Soft Computing book series (STUDFUZZ, volume 90)


Here is a framework for judgment in terms of a continuum of “subjective” probabilities, a framework in which probabilistic judgments need not stand on a foundation of certainties. In place of propositional data bases, this radical probabilism (“probabilities all the way down to the roots”) envisages full or partial probability assignments to probability spaces, together with protocols for revising those assignments and their interconnections in the light of fresh empirical or logico-mathematical input. This input need not be of the limiting 0-or-1 sort. Updating by ordinary conditioning is generalized (sec. 2.2) to probability kinematics, where an observation on a random variable X need not single out one value, but may prompt a new probability distribution Q over all values of X.

The effect of an observation itself, apart from the influence of prior probabilities (sec. 3), is given by the (“Bayes”) factors \(\frac{{new\;odds}}{{old\;odds}}\) by which the observer’s odds between hypotheses are updated. We are not generally interested in adopting an observer’s new odds as our own, for those are influenced by the observer’s old odds, not ours. It is rather the observer’s Bayes’s factors that we need in order to use that observation in our own judgments. An account of collaborative updating is presented in these terms.

Jon Dorling’s bayesian solution of the Duhem-Quine “holism” problem is sketched in sec. 4.

We finish with a brief look at the historical setting of radical probabilism (sec. 5), and an indication of how “real” probabilities can be accomodated in subjectivistic terms (sec. 6).


Subjective Probability Radical Probabilism Probabilistic Judgment Green Ball Auxiliary Hypothesis 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Arnauld, Antoine ( 1662, 1964) Logic, or, the Art of Thinking (“The Port-Royal Logic”) tr. J. Dickoff and P. James, Bobbs-Merril, Indianapolis.Google Scholar
  2. Bayes, Thomas (1763) An essay towards solving a problem in the doctrine of chances, Philosophical Transactions of the Royal Society 53, 370–418.CrossRefGoogle Scholar
  3. Carnap, R. (1950), Logical Foundations of Probability, Chicago: University of Chicago Press. (2nd ed., 1962 )Google Scholar
  4. de Finetti, Bruno (1937, 1980 ) La prévision, ses lois logiques, ses sources subjectives, Annales de l’institut Henri Poincaré 7, 1–68. Translation (“Foresight… ”) in Studies in Subjective Probability, Henry Kyburg, Jr. and Howard Smokier (eds.), Krieger, New York, 53–118.Google Scholar
  5. Diaconis, Persi and Sandy Zabell (1989) Updating Subjective Probability, Journal of the American Statistical Society 77, 822–30.MathSciNetGoogle Scholar
  6. Dorling, Jon (1979) Bayesian personalism, the methodology of research programmes, and Duhem’s problem, Studies in History and Philosophy of Science 10, 177–87.MathSciNetMATHCrossRefGoogle Scholar
  7. Dorling, Jon (1982) Further illustrations of the Bayesian solution of Duhem’s problem (29 pp., photocopied); see http:\\www.princeton.edu\ -,bayesway Google Scholar
  8. Duhem, Pierre (1906, 1914. 1954) La Théorie Physique: Son Object, Sa Structure,Paris. Translation, The Aim and Structure of Physical Theory. Princeton University Press.Google Scholar
  9. Field, Hartry (1978) A Note on Jeffrey Conditionalization, Philosophy of Science 45, 361–7.MathSciNetCrossRefGoogle Scholar
  10. Howson, Colin and Peter Urbach (1993) Scientific Reasoning: the Bayesian approach, Open Court, La Salle, Illinois, 2nd ed.Google Scholar
  11. Jeffrey, Richard (1970) [untitled review of Miller (1966) and other papers] Journal of Symbolic Logic 35, 124–127.Google Scholar
  12. Jeffrey, Richard (1992) Probability and the Art of Judgment, Cambridge U. P.CrossRefGoogle Scholar
  13. Lewis, C. I. (1946) An Analysis of Knowledge and Valuation,Open Court.Google Scholar
  14. Miller, David (1966) A Paradox of Information, British Journal for the Philosophy of Science 17, 59–61.CrossRefGoogle Scholar
  15. Neurath, Otto (1932), Protokollstze, Erkenntnis 3, 204–214. Translated in his Philosophical Papers 1913–1946,Dordrecht: Reidel.Google Scholar
  16. Quine, Willard van Orman (1951. 1953 ) Two Dogmas of Empiricism, Philosophical Review 60, 20–43. Reprinted in From a Logical Point of View, Harvard University Press.Google Scholar
  17. Redhead, Michael (1980) A Bayesian reconstruction of the methodology of scientific research programmes. Studies in History and Philosophy of Science 11, 341–7.MathSciNetCrossRefGoogle Scholar
  18. Schwartz, W.B., Wolfe, H.J., and Pauker, S.G. (1981) Pathology and Probabilies: A New Approach to Interpreting and Reporting Biopsies, The New England Journal of Medicine 305, 917–23.CrossRefGoogle Scholar
  19. van Fraassen, Bas (1984) Belief and the will, J. Philosophy 65, 243–60.Google Scholar
  20. Zabell, Sandy (1989) The Rule of Succession. Erkenntnis 31, 283–321.CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2002

Authors and Affiliations

  • Richard Jeffrey
    • 1
  1. 1.Department of PhilosophyPrinceton UniversityPrincetonUSA

Personalised recommendations