Résumé
We point out a simple but hitherto ignored link between the theory
of updates, the theory of
counterfactuals, and classical modal logic: update is a classical
existential modality, counterfactual is a classical universal
modality, and the accessibility relations corresponding to these modalities are inverses. The Ramsey Rule (often thought esoteric) is simply an axiomatisation of this inverse relationship.
We use this fact to translate between rules for updates and
rules for counterfactuals. Thus, Katsuno/Mendelzon's postulates
are translated into counterfactual rules, and many of the familiar counterfactual rules
are translated into rules for updates.
An open question is whether all rules for updates may be translated
into rules for counterfactuals, and vice versa. We present a
syntactic condition which is sufficient to guarantee that a
translation from update to counterfactual (or vice versa) is possible.
langue originale | Anglais |
---|---|
Pages (de - à) | 123-146 |
Nombre de pages | 24 |
journal | Journal of Logic, Language and Information |
Volume | 6 |
Numéro de publication | 2 |
Etat de la publication | Publié - 1997 |