Notre Dame Journal of Formal Logic

Impossible Worlds: A Modest Approach

Daniel Nolan


Reasoning about situations we take to be impossible is useful for a variety of theoretical purposes. Furthermore, using a device of impossible worlds when reasoning about the impossible is useful in the same sorts of ways that the device of possible worlds is useful when reasoning about the possible. This paper discusses some of the uses of impossible worlds and argues that commitment to them can and should be had without great metaphysical or logical cost. The paper then provides an account of reasoning with impossible worlds, by treating such reasoning as reasoning employing counterpossible conditionals, and provides a semantics for the proposed treatment.

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Notre Dame J. Formal Logic Volume 38, Number 4 (1997), 535-572.

First available: 10 December 2002

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Primary: 03A05: Philosophical and critical {For philosophy of mathematics, see also 00A30}
Secondary: 03B45: Modal logic (including the logic of norms) {For knowledge and belief, see 03B42; for temporal logic, see 03B44; for provability logic, see also 03F45} 03B53: Paraconsistent logics


Nolan, Daniel. Impossible Worlds: A Modest Approach. Notre Dame Journal of Formal Logic 38 (1997), no. 4, 535--572. doi:10.1305/ndjfl/1039540769.

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