Tuesday, 26 January 2016

Indicative Modality is Not Epistemic

Philosophers today frequently identify indicative modality with apriority, or at least identify it as an epistemic notion.

For instance, the abstract for a recent talk by Greg Restall (currently available at his website) refers to 'subjunctive (metaphyisical) and indicative (epistemic) modalities'.

Even Chalmers in his admirable piece on the tyranny of the subjunctive, which might be expected to resist this tendency, bites the bullet here. Witness:

(a) Indicative necessity is "merely epistemic".
    [Answer: So? Before 1970, almost everyone thought necessity was tied to the epistemic (cf. Pap's book). Kripke *argued* that necessity and epistemic notions came apart, by appeal to the subjunctive, but one can't simply presuppose it.]

This is a mistake. Indicative modality is not epistemic. A proposition is subjunctively necessarily true when it could not have been false, no matter what. A proposition is indicatively necessarily true when it cannot be false, no matter what.

I see no reason to think we need to understand this latter notion by appealing to anything to do with knowledge or a knowing subject. The idea is rather that an indicatively necessary proposition is true by its very nature, or has truth as an internal property.

It may be that a proposition is a priori iff it is indicatively necessary (or maybe the two categories are almost but not completely aligned). I once proposed something like this as an analysis of the concept of apriority. While this may still be an instructive result, shedding light on apriority and indicative necessity both, I no longer think it should be thought of as giving the content or intension of the notion of apriority. That should be left as a concept which has to do with knowledge or knowability, and indicative necessity recognized as an interesting, and non-epistemic, concept in its own right.

This point is just a continuation of Kripke's work in distinguishing concepts of propositional typology which have typically been conflated.

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