Coping with Ethical Uncertainty

John R. Welch

About author

John R. Welch, PhD
Saint Louis University - Madrid Campus
Department of Philosophy
Avenida del Valle, 34
28003 Madrid



Most ethical decisions are conditioned by formidable uncertainty. Decision makers may lack reliable information about relevant facts, the consequences of actions, and the reactions of other people. Resources for dealing with uncertainty are available from standard forms of decision theory, but successful application to decisions under risk requires a great deal of quantitative information: point-valued probabilities of states and point-valued utilities of outcomes. When this information is not available, this paper recommends the use of a form of decision theory that operates on a bare minimum of information inputs: comparative plausibilities of states and comparative utilities of outcomes. In addition, it proposes a comparative strategy for dealing with second-order uncertainty. The paper illustrates its proposal with reference to a well-known ethical dilemma: Kant’s life-saving lie.

Full Text:



  1. Allen R.J. (1994), “Factual Ambiguity and a Theory of Evidence,” Northwestern University Law Review 88 (2): 604–640.
  2. Allen R.J., Pardo M.S. (2007), “The Problematic Value of Mathematical Models of Evidence,” Journal of Legal Studies 36 (1): 107–140.
  3. Anscombe F.J., Aumann R.J. (1963), “A Definition of Subjective Probability,” The Annals of Mathematical Statistics 34 (1): 199–205.
  4. Aristotle (1984), The Complete Works of Aristotle, J. Barnes (ed.), Princeton University Press, Princeton.
  5. Aven T. (2008), Risk Analysis: Assessing Uncertainties beyond Expected Values and Probabilities, Wiley, Chichester, England and Hoboken (NJ).
  6. Chu F.C., Halpern J.Y. (2004), “Great Expectations. Part II: Generalized Expected Utility as a Universal Decision Rule,” Artificial Intelligence 159 (1–2): 207–229.
  7. Chu F.C., Halpern J.Y. (2008), “Great Expectations. Part I: On the Customizability of Generalized Expected Utility,” Theory and Decision 64 (1): 1–36.
  8. Fishburn P.C. (1991), “Non-transitive Preferences in Decision Theory,” Journal of Risk and Uncertainty 4 (2): 113–134.
  9. Friedman N., Halpern J.Y. (1995), “Plausibility Measures: A User’s Guide,” [in:] Proceedings of the Eleventh Conference on Uncertainty in Artificial Intelligence (UAI ’95): 175–184, URL = [Accessed 26.8.2017].
  10. Friedman N., Halpern J.Y. (2001), “Plausibility Measures and Default Reasoning,” Journal of the ACM 48 (4): 648–685.
  11. Gilboa I. (2009), Theory of Decision under Uncertainty, Cambridge University Press, Cambridge.
  12. Gowans C.W. (ed.) (1987), Moral Dilemmas, Oxford University Press, New York.
  13. Greenspan P. (1983), “Moral Dilemmas and Guilt,” Philosophical Studies 43 (1): 117–125.
  14. Halpern J.Y. (2003), Reasoning about Uncertainty, The MIT Press, Cambridge (MA).
  15. Jeffrey C.R. (1965), “Ethics and the Logic of Decision,” The Journal of Philosophy 62 (19): 528–539.
  16. Kant I. (1996), On a Supposed Right to Lie from Philanthropy, trans. M.J. Gregor, [in:] I. Kant, Practical Philosophy, M.J. Gregor (ed.), Cambridge University Press, Cambridge: 605–615.
  17. Kaplan S., Garrick B.J. (1981), “On the Quantitative Definition of Risk,” Risk Analysis 1 (1): 11–27.
  18. Keats J. (2009), “To George and Tom Keats, December 21, 27 (?) December 1817,” [in:] Selected Letters of John Keats: Based on the Texts of Hyder Edward Rollins, rev. ed., G.F. Scott (ed.), Harvard University Press, Cambridge (MA): 59–61.
  19. Klir G.J. (2006), Uncertainty and Information: Foundations of Generalized Information Theory, John Wiley & Sons, Hoboken.
  20. Larmore C. (2008), The Autonomy of Morality, Cambridge University Press, Cambridge.
  21. Lewis H.W. et al. (1978), Risk Assessment Review Group Report to the U. S. Nuclear Regulatory Commission, NUREG/CR-0400, URL =
  22. NCLCollectionStore/_Public/10/452/10452296.pdf [Accessed 26.8.2017].
  23. National Research Council (1975), Reactor Safety Study: An Assessment of Accident Risks in U. S. Commercial Nuclear Power Plants, National Academy Press, Washington (DC).
  24. Pardo M.S. (2000), “Juridical Proof, Evidence, and Pragmatic Meaning: Toward Evidentiary Holism,” Northwestern University Law Review 95 (1): 399–442.
  25. Paris J.B. (1994), The Uncertain Reasoner’s Companion: A Mathematical Perspective, Cambridge University Press, Cambridge.
  26. Peirce C.S. (1986), “The Fixation of Belief,” [in:] Writings of Charles S. Peirce: A Chronological Edition, vol. 3, C.J.W. Kloesel (ed.), Indiana University Press, Bloomington: 242–257.
  27. Pólya G. (1954), Mathematics and Plausible Reasoning, 2 vols., Princeton University Press, Princeton.
  28. Ramsey F.P. (1931), Truth and Probability, [in:] The Foundations of Mathematics and Other Logical Essays, R.B. Braithwaite (ed.), Kegan, Paul, Trench, Trubner & Co., London; and Harcourt, Brace and Company, New York: 156–198.
  29. Rescher N. (1976), Plausible Reasoning: An Introduction to the Theory and Practice of Plausibilistic Inference, Van Gorcum, Assen/Amsterdam.
  30. Rott H. (2003), “Basic Entrenchment,” Studia Logica 73 (2): 257–280.
  31. Rott H. (2014), “Two Concepts of Plausibility in Default Reasoning,” Erkenntnis 79 (6): 1219–1252.
  32. Savage L.J. (1971), “Elicitation of Personal Probabilities and Expectations,” Journal of the American Statistical Association 66 (336): 783–801.
  33. Shafer G. (1987), Belief Functions and Possibility Measures, [in:] Analysis of Fuzzy Information, vol. I, J.C. Bezdek (ed.), CRC Press, Boca Raton: 51–84.
  34. Shrader-Frechette K. (1991), Risk and Rationality: Philosophical Foundations for Populist Reforms, University of California Press, Berkeley.
  35. Van Horn K.S. (2003), “Constructing a Logic of Plausible Inference: A Guide to Cox’s Theorem,” International Journal of Approximate Reasoning 23 (1): 3–24.
  36. Walton D. (2001), “Abductive, Presumptive and Plausible Arguments,” Informal Logic 21 (2): 141–169.
  37. Walton D. (2004), Abductive Reasoning, University of Alabama Press, Tuscaloosa (AL).
  38. Welch J.R. (2007), “Vagueness and Inductive Molding,” Synthese 154 (1): 147–172.
  39. Welch J.R. (2011), “Decision Theory and Cognitive Choice,” European Journal for Philosophy of Science 1 (2): 147–172.
  40. Welch J.R. (2012), “Real-Life Decisions and Decision Theory,” [in:] Handbook of Risk Theory, S. Roeser, R. Hillerbrand, P. Sandin, M. Peterson (eds), Springer, Dordrecht: 545–573.
  41. Welch J.R. (2013), “New Tools for Theory Choice and Theory Diagnosis,” Studies in History and Philosophy of Science Part A 44 (3): 318–329.
  42. Welch J.R. (2014), Moral Strata: Another Approach to Reflective Equilibrium, Springer, Cham.
  43. Zimmerman M.J. (1996), The Concept of Moral Obligation, Cambridge University Press, Cambridge.


Article links:

Default URL:
English abstract URL:


All works are licensed under a Attribution-NonCommercial 4.0 International (CC BY-NC 4.0) License.