- In 'Modal2 Infallibilism and Basic Truth' Scott Sturgeon investigates further3 the relationship between metaphysical possibility and intelligibility.
- Most philosophers agree that apriori reflection provides at best a fallible guide to genuine possibility. The schema (L) that says: if a proposition is intelligible then it is genuinely possible, is generally recognized not to be valid.
- Nevertheless, Sturgeon argues, philosophers have frequently failed to practise what they preach. They have been led by (L) to advance contradictory claims about the fundamental structure of reality.
- Sturgeon provides as a representative example of the capacity of (L) to mislead, a battery of six basic metaphysical claims about change and identity that Lewis has advanced but together generate contradiction. They generate contradiction because. Sturgeon maintains, Lewis accepts at least one instance of (L), inferring from the intelligibility of objects that endure identically through time — Sturgeon calls these 'enduring runabouts' — that such objects are genuinely possible.
- The contradiction Sturgeon uncovers suggests that (L), if it is true at all, must be significantly qualified. But, Sturgeon argues, there is no restricted reading of (L) that is valid either.
- The first restriction Sturgeon considers qualifies (L) to accommodate Kripke's insight that there are intelligible propositions that fail to mark genuine possibility because the negations of these propositions are aposteriori necessary.
- Sturgeon rejects (L) so qualified because there is at least one intelligible proposition P whose equally intelligible negation not-P fails to be aposteriori necessary but nevertheless it cannot be the case that P and not-P are both genuinely possible.
- Sturgeon provides as an example of such a P the Lewisian proposition that concrete possible worlds are the truth-makers for claims of genuine possibility.
- After considering yet further unsatisfactory qualifications to (L) Sturgeon concludes that philosophers have been misled by the 'ep-&-met tendency', the human tendency to fuse epistemic and metaphysical matters; what is required is to recognize where this tendency misleads us whilst — and this is where the task becomes almost insuperably difficult — continuing to respect the fact that it is a cornerstone of our modal4 practice that intelligibility defeasibly marks genuine possibility.
- Six Claims of Basic Metaphysics
- Two Problems
Footnote 1: Footnote 3: Further, that is, to "Rosen (Gideon) - The Limits of Contingency".
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