Deontic Modals and Probabilities: One Theory to Rule Them All?

Abstract

This paper motivates and develops a novel semantic framework for deontic modals. The framework is designed to shed light on two things: the relationship between deontic modals and substantive theories of practical rationality and the interaction of deontic modals with conditionals, epistemic modals and probability operators. I argue that, in order to model inferential connections between deontic modals and probability operators, we need more structure than is provided by classical intensional theories. In particular, we need probabilistic structure that interacts directly with the compositional semantics of deontic modals. However, I reject theories that provide this probabilistic structure by claiming that the semantics of deontic modals is linked to the Bayesian notion of expectation. I offer a probabilistic premise semantics that explains all the data that create trouble for the rival theories.

Advice for Noncognitivists

“…The point is also observed by Heim () and Stalnaker (), and more recently by Silk (). It is compatible with the claim that the relevant attitudes are sometimes sensitive to features of an information state that arguably resist an adequate characterization as an attitude toward possible worlds, for instance to credences (as discussed by Cariani () and Yalcin (), among others), though capturing such sensitivities would require a more complex model of an agent's state of mind.…”

Modality, Scale Structure, and Scalar Reasoning

“…As long the worst possible outcome (death) is still a live possibility, Maximin continues to predict that it is better for Juliet not to take the drug as long as there is any possibility, however slight, that the Friar will not administer the antidote. (For related criticisms see Carr, ; Cariani, . )…”

“…Charlow () follows Carr in rejecting the expected‐value theory (along with any other ‘contentful’ semantics for ought ) on the grounds that it rules out too much as a matter of meaning. Cariani (), too, seems to be sympathetic with the idea that there is a methodological advantage for ‘neutral’ semantic theories (though he ultimately focuses on empirical questions). All three opt for much less restrictive theories which can generate the predictions of the expected‐value semantics among many others.…”

“…'s () core ideas can be implemented in a weaker semantics which permits Maximin among many other decision rules, and which is able to cope with the effects of shifting probability. See Cariani, for the details. Like the von Fintel/proposal discussed in the previous footnote, I think that Cariani's extremely permissive semantics is dispreferred on general methodological grounds absent a strong empirical argument against the expected‐value semantics.…”

“…Charlow () does give several empirical arguments for this conclusion which are distinct from the high‐level methodological claim that I discuss here. See Lassiter, , for a detailed reply to these, and to the empirical criticisms that Cariani () levels at the expected‐value semantics specifically.…”