, Volume 131, Issue 1, pp 39–56 | Cite as

A Brief Comparison Of Pollock's Defeasible Reasoning And Ranking Functions

  • Wolfgang Spohn


In this paper two theories of defeasible reasoning, Pollock's account and my theory of ranking functions, are compared, on a strategic level, since a strictly formal comparison would have been unfeasible. A brief summary of the accounts shows their basic difference: Pollock's is a strictly computational one, whereas ranking functions provide a regulative theory. Consequently, I argue that Pollock's theory is normatively defective, unable to provide a theoretical justification for its basic inference rules and thus an independent notion of admissible rules. Conversely, I explain how quite a number of achievements of Pollock's account can be adequately duplicated within ranking theory. The main purpose of the paper, though, is not to settle a dispute with formal epistemology, but rather to emphasize the importance of formal methods to the whole of epistemology.


Formal Method Inference Rule Ranking Function Basic Difference Theoretical Justification 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Carnap, R.: 1950, Logical Foundations of Probability, Chicago University Press, Chicago, 2nd edn (1962).Google Scholar
  2. Gärdenfors, P.: 1988, Knowledge in Flux, MIT Press, Cambridge, MA.Google Scholar
  3. Goldszmidt, M. and J. Pearl (1992), ‘Rank-Based Systems: A Simple Approach to Belief Revision, Belief Update, and Reasoning About Evidence and Actions', in Proceedings of the Third International Conference on Principles of Knowledge Representation and Reasoning, Cambridge, MA.Google Scholar
  4. Haas-Spohn, U. and W. Spohn: 2001, ‘Concepts are Beliefs about Essences', in A. Newen, U. Nortmann, and R. Stuhlmann-Laeisz (eds), Building on Frege. New Essays on Sense, Content, and Concept, CSLI Publications, Stanford, pp. 287–316.Google Scholar
  5. Harper, W. L.: 1976, ‘Rational Belief Change, Popper Functions, and Counterfactuals', in W. L. Harper and C. A. Hooker (eds), Foundations of Probability Theory, Statistical Inference, and Statistical Theories of Science, Vol. I, Reidel, Dordrecht, pp. 73–115.Google Scholar
  6. Hintikka, J.: 1962, Knowledge and Belief, Cornell University Press, Ithaca, NY.Google Scholar
  7. Jeffrey, R. C.: 1965, The Logic of Decision, The University of Chicago Press, Chicago, 2nd edn 1983).Google Scholar
  8. Jensen, F. V.: 1996, An Introduction to Bayesian Networks, UCL Press, London.Google Scholar
  9. Kelly, K.: 1996, The Logic of Reliable Inquiry, Oxford University Press, Oxford.Google Scholar
  10. Kelly, K.: 1999, ‘Iterated Belief Revision, Reliability, and Inductive Amnesia', Erkenntnis 50, 11–58.Google Scholar
  11. Levi, I.: 1967, ‘Probability Kinematics', British Journal for the Philosophy of Science 18, 197–209.Google Scholar
  12. Levi, I.: 1991, ‘The Fixation of Belief and Its Undoing, Cambridge University Press, Cambridge.Google Scholar
  13. Levi, I.: 1996, For the Sake of Argument, Cambridge University Press, Cambridge.Google Scholar
  14. Nayak, A. C.: 1994, ‘Iterated Belief Change Based on Epistemic Entrenchment', Erkenntnis 41, 353–390.Google Scholar
  15. Pearl, J.: 1988, Probabilistic Reasoning in Intelligent Systems: Networks of Plausible Inference, Morgan Kaufmann, San Mateo, CA.Google Scholar
  16. Pollock, J. L.: 1990, Nomic Probability and the Foundations of Induction, Oxford University Press, Oxford.Google Scholar
  17. Pollock, J. L.: 1995, Cognitive Carpentry, MIT Press, Cambridge, MA.Google Scholar
  18. Pollock, J. L.: 1998, ‘Procedural Epistemology - At the Interface of Philosophy and AI', in J. Greco and E. Sosa (eds), The Blackwell Guide to Epistemology, Blackwell, Oxford, pp. 383–414.Google Scholar
  19. Pollock, J. L. and J. Cruz: 1999, Contemporary Theories of Knowledge, 2nd edn, Rowman & Littlefield, Lanham, MD.Google Scholar
  20. Pollock, J. L. and A. S. Gillies: 2001, ‘Belief Revision and Epistemology', Synthese (forthcoming).Google Scholar
  21. Rescher, N.: 1964, Hypothetical Reasoning, North-Holland, Amsterdam.Google Scholar
  22. Rott, H.: 2001, Change, Choice, and Inference, University Press, Oxford.Google Scholar
  23. Shackle, G. L. S.: 1961, Decision, Order, and Time in Human Affairs, Cambridge University Press, Cambridge, 2nd edn, 1969.Google Scholar
  24. Spohn, W.: 1983, Eine Theorie der Kausalität, unpublished Habilitationsschrift, Munich.Google Scholar
  25. Spohn, W.: 1988, ‘Ordinal Conditional Functions. A Dynamic Theory of Epistemic States', in W. L. Harper and B. Skyrms (eds), Causation in Decision, Belief Change, and Statistics, Vol. II, Kluwer, Dordrecht, pp. 105–134.Google Scholar
  26. Spohn, W.: 1994, ‘On the Properties of Conditional Independence', in P. Humphreys (ed.), Patrick Suppes: Scientific Philosopher, Vol. 1: Probability and Probabilistic Causality, Kluwer, Dordrecht, 1994, pp. 173–194.Google Scholar
  27. Spohn, W.: 1997/98, ‘How to Understand the Foundations of Empirical Belief in a Coherentist Way', Proceedings of the Aristotelian Society, New Series 98, 23–40.Google Scholar
  28. Spohn, W.: 1999, ‘Ranking Functions, AGM Style', Forschungsberichte der DFG-Forschergruppe Logik in der Philosophie, No. 28, also in B. Hansson, S. Halldán, N.-E. Sahlin, and W. Rabinowicz (eds), Internet-Festschrift for Peter Gärdenfors, Lund, s.: Scholar
  29. Spohn, W.: 2001a, ‘Deterministic Causation', in W. Spohn, M. Ledwig, and M. Esfeld, (eds), Current Issues in Causation, Mentis, Paderborn, pp. 21–46.Google Scholar
  30. Spohn, W.: 2001b, ‘Vier Begründungsbegriffe', in T. Grundmann (ed.), Challenges to Traditional Epistemology, Mentis, Paderborn, pp. 33–52.Google Scholar

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Wolfgang Spohn
    • 1
  1. 1.Fachbereich PhilosophieUniversität KonstanzKonstanzGermany

Personalised recommendations