- In 'The Limits of Contingency' Gideon Rosen sets out to examine the modal2 status of metaphysical and mathematical propositions.
- Typically such propositions — that, for example, universals3 or aggregates or sets exist — are claimed to be metaphysically necessary. But such claims of metaphysical necessity, Rosen maintains, are inherently deficient. This is because the kinds of elucidation philosophers typically offer of the concept of metaphysical necessity fail to pin down a unique concept of necessity; in fact no conception exactly fits the elucidations given, and at least two conceptions — which Rosen dubs 'Standard' and 'Non-Standard' — fit the elucidations equally well.
- According to the Standard Conception, the synthetic apriori truths of basic ontology are always necessary.
- By contrast, according to the Non-Standard Conception, such truths are sometimes contingent.
- Consider, for example, Armstrong's claim that qualitative similarity between particulars is secured by the recurrence of immanent universals4.
So, if it is true, Armstrong's claim tells us only about how similarity happens to be secured in the actual world; in other possible worlds similarity is secured differently.
- By the lights of the Standard Conception this claim, if it is true, is metaphysically necessary. For whilst it is not a logical or a conceptual necessity — there is no reason to think its denial self-contradictory or otherwise inconceivable — it is not aposteriori either.
- But, by the lights of the Non-Standard Conception, Armstrong's claim is contingent. For other metaphysical accounts that eschew universals5 — in favour, for example, of duplicate tropes — are also compatible with the nature of the similarity relation.
- Since philosophical elucidations of the concept of metaphysical necessity favour neither the Standard nor the Non-Standard Conception Rosen concludes that philosophical discourse about metaphysical necessity is shot through with ambiguity, an ambiguity that we ignore at our peril.
- What is Metaphysical Necessity?
- An Informal Elucidation
- A Question about the Informal Elucidation
- The Standard Conception and the Differential Class
- The Non-Standard Conception
- The Two Conceptions and the Informal Explanation
- Is the Non-Standard Conception Coherent?
- Objections to the Standard Conception
- Physical Necessity Reconsidered
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