The If P, Ought P Problem

Abstract

Kratzer semantics for modals and conditionals generates the prediction that sentences of the form if p, ought p are trivially true. As Frank and Zvolenszky show, for certain flavors of modality, like deontic modality, this prediction is false. I explain some conservative solutions to the problem, and then argue that they are inadequate to account for puzzle cases involving self-frustrating oughts. These cases illustrate a general problem: there are two forms of information-sensitivity in deontic modals. Even generalizations of Kratzer semantics that predict these two roles for information, e.g. Kolodny and MacFarlane, predict that they vary together. I propose a generalization of Kratzer semantics that allows the two roles for information to vary independently of each other.

Intervention in deontic reasoning

“…A similar point has been made by Carr (2014). Consider the following scenario originally due to Gibbard & Harper (1978).…”

“…As a side effect, lawlike dependencies between the prejacent and facts that causally affect the prejacent are ignored in interpreting must/should/ought. The upshot for the theory of modality is that for intuitively true cases of 'if p, must/should/ought p' discussed in Zvolenszky (2002) and Carr (2014), we can set up a coherent modal background of the deontic modal. The task has been known to be difficult without making certain unnatural assumptions about the worlds under consideration.…”

“…Section 7 fleshes out the analysis, and Section 8 presents empirical arguments in favor of an interventionist approach to counterfactuals. Section 9 compares the proposed analysis with Carr's (2014) theory of deontic conditionals.…”

“…(18) Self-frustrating ought (Carr 2014) If you are in the same city as Death tomorrow, then you'll die. Death has planned to be wherever he predicts you'll be, and he's very reliable in such predictions.…”

“…Concerning the self-frustrating ought examples, Carr (2014) points out that there is no natural way to tear apart the propositions 'you are in Aleppo' and 'Death is in Aleppo', because one is inferred from the other. Carr invokes causal decision theory, in which the causal expected utility of acts are compared.…”