MoL-2018-28: Counterfactuals and the Logic of Imaginative Content

MoL-2018-28: McHugh, Dean (2018) Counterfactuals and the Logic of Imaginative Content. [Report]

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Much of what we say aims to spark the imagination rather than inform. Imperatives to imagine such as “Imagine you are eating coconut ice cream” as well as counterfactual antecedents such as “If we hadn’t met at the gelato bar...” serve to raise hypothetical contexts. This essay is about the logic of such imaginative talk. In particular, we analyse how three words—and, or, and not—evoke imagined scenarios. The resulting semantics, which we axiomatise, combines contemporary developments in fine-grained semantics (principally, truthmaker and inquisitive semantics), although the logic turns out to be something new.
At the heart of the present account is the construction of a semantic object representing the ‘ways of imagining’ conjunctions, disjunctions and negations true. This object is designed to express the ‘imaginative content’ of a sentence, which, we show, differs markedly from its informative content.
All of this is motivated by the idea that to understand the meaning of the words and, or and not in counterfactual antecedents we must understand their contribution in evoking hypothetical contexts. Since counterfactuals are modal contexts, inviting us to look beyond the actual world, we therefore present and strongly axiomatise some ‘imaginative’ modal logics that serving as the basis for a logic of counterfactuals in which counterfactual antecedents are interpreted in terms of their imaginative content. On this approach, a counterfactual is true just in case the consequent holds under every way of imagining the antecedent true.
Our final substantive chapter highlights one model in particular of the counterfactual logic we present. In this model—which it is tempting to call the standard model—a sentence’s imaginative content is understood as a list of ways to change the atomic facts of actual world to imagine the sentence true, and a counterfactual is true just in case the consequent holds under every way of changing the atomic facts of the actual world to imagine the sentence true. We show that this semantics of counterfactuals in terms of atomic change validates a number of desirable rules of inference of counterfactual logic while avoiding some undesirable ones.
We conclude with some puzzles for the reader.

Item Type: Report
Report Nr: MoL-2018-28
Series Name: Master of Logic Thesis (MoL) Series
Year: 2018
Subjects: Logic
Depositing User: Dr Marco Vervoort
Date Deposited: 26 Oct 2018 14:04
Last Modified: 26 Oct 2018 14:04

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