Kripkean Epistemically Possible Worlds

ISBN: 978-3-88405-502-1

Abstract to Contribution

Dale Jacquette, in “Kripkean Epistemically Possible Worlds”, develops two applied formal logics of epistemic modalities in order to assess Kripke’s controversial conclusions in Naming and Necessity that there are logically necessary a posteriori propositions (Kripke’s version of Frege’s example involving Hesperus = Phosphorus, where ‘Hesperus’ and ‘Phosphorus’ are understood as rigid designators), and logically contingent a priori propositions (Kripke’s version of Wittgenstein’s example involving the standard metre stick in Paris). Jacquette argues in both cases that Kripke can sustain his arguments only by adopting implausible assumptions to uphold the needed identity determinations across logically possible worlds. The implication is that Kripke’s celebrated proofs for logically necessary aposteriority and logically contingent aprioricity are inconclusive. An epistemic modal logic needed to support Kripke’s counterexamples to the expected association of logical necessity with a priori knowledge and of logical contingency with a posteriori knowledge, might yet be adopted, but only at a significant intuitive disadvantage. The essay in its constructive component presents a rigorous modeling of relevant modal concepts in which formal structures include accessibility relations among epistemically possible worlds, as well as offering insight into the logic of a priori and a posteriori knowledge.

Authors Biography

Dale Jacquette, in “Kripkean Epistemically Possible Worlds”, develops two applied formal logics of epistemic modalities in order to assess Kripke’s controversial conclusions in Naming and Necessity that there are logically necessary a posteriori propositions (Kripke’s version of Frege’s example involving Hesperus = Phosphorus, where ‘Hesperus’ and ‘Phosphorus’ are understood as rigid designators), and logically contingent a priori propositions (Kripke’s version of Wittgenstein’s example involving the standard metre stick in Paris). Jacquette argues in both cases that Kripke can sustain his arguments only by adopting implausible assumptions to uphold the needed identity determinations across logically possible worlds. The implication is that Kripke’s celebrated proofs for logically necessary aposteriority and logically contingent aprioricity are inconclusive. An epistemic modal logic needed to support Kripke’s counterexamples to the expected association of logical necessity with a priori knowledge and of logical contingency with a posteriori knowledge, might yet be adopted, but only at a significant intuitive disadvantage. The essay in its constructive component presents a rigorous modeling of relevant modal concepts in which formal structures include accessibility relations among epistemically possible worlds, as well as offering insight into the logic of a priori and a posteriori knowledge.