Counterfactual Desirability

Br J Philos Sci. 2017 Jun;68(2):485-533. doi: 10.1093/bjps/axv023. Epub 2015 Aug 4.

Abstract

The desirability of what actually occurs is often influenced by what could have been. Preferences based on such value dependencies between actual and counterfactual outcomes generate a class of problems for orthodox decision theory, the best-known perhaps being the so-called Allais paradox. In this article we solve these problems by extending Richard Jeffrey's decision theory to counterfactual prospects, using a multidimensional possible-world semantics for conditionals, and showing that preferences that are sensitive to counterfactual considerations can still be desirability-maximizing. We end the article by investigating the conditions necessary and sufficient for a desirability function to be a standard expected-utility function. It turns out that the additional conditions imply highly implausible epistemic principles. 1Two Paradoxes of Rational Choice2Jeffrey Desirability3Counterfactuals 3.1Probability and desirability of counterfactuals3.2Representations4Counterfactual-Dependent Preferences 4.1Preference actualism and desirability maximization4.2Modelling Allais's and Diamond's preferences5Ethical Actualism and Separability 5.1Independence and additive separability5.2 Ethical actualism5.3Expected utility, separability, and ethical actualism6Concluding Remarks7Appendix.