*This post is quite compressed and relies on things explained in the previous posts on the task of linking necessity to apriority, as well as alluding to my account of necessity as expressed in my PhD thesis. In a future post, I intend to explain and explore what these developments mean for my account of necessity.*

There has recently appeared an unpublished manuscript on PhilPapers (PDF available here at time of writing) which contains even stronger counterexamples to both Casullo's and my proposed link between necessity and apriority. It is by Margot Strohminger and Yuhani Yli-Vakkuri.

Strohminger & Yli-Vakkuri argue that Kipper's examples are contentious, relying on dubitable assumptions about natural kind terms and perhaps even embracing what they call 'Chalmersian two-dimensionalist ideology'. They provide even simpler examples of propositions whose general modal status cannot be known

*a priori*(and, relevantly for me, these examples also don't seem to be

*implied*by propositions whose general modal status can be known

*a priori*). For example:

Bob Dylan is at least as tall as Robert Zimmerman.This is necessary, since Bob Dylan

*is*Robert Zimmerman. But for all we can know

*a priori*, Dylan and Zimmerman are distinct, in which case this proposition would not be necessary, but contingent.

But hold on a minute! My link appeals to implication, and I said that the example above isn't implied by a proposition whose general modal status is knowable

*a priori*. But can't we say that it is implied by 'Bob Dylan is Robert Zimmerman', which we can know

*a priori*to be necessary? Yes, we can - although here we need a notion of implication which takes into account the meaning of 'is at least as tall as' - or at least the fact that it's a certain kind of comparative expression - rather than just the meanings of subject-neutral particles like 'or', 'all' and 'some'. So, from the point of view of disproving Casullo's proposed link, this example may be the best available so, but from the point of view of disproving my proposed implication-involving link, Kipper's natural kind examples may still have an edge.

It seems to be a very exciting time to be thinking about these issues! So far, in this post and the last, I've been talking about how these examples affect my proposed link between necessity and apriority. But the situation is more serious than that for me. The centrepiece of my PhD thesis was an account of the conditions under which a proposition is necessarily true (I've blogged about this account quite a bit here). And these developments, as far as I can tell, may well show that account to be false. This is very momentous for me, as I worked on that account for several years and considered it to be maybe my best bit of work.

I can't believe I didn't think of the example above in connection with my account! I even considered a very similar example when making a side point about using my notion of a genuine counterfactual scenario description (used in my account of necessity) to arrive at a definition of rigid designation which is in some ways more fundamental than the Kripkean one.

Stay tuned for more on whether and how these developments affect my account of necessity, and what can be done about it if they do.

I thought we went through this with your "Hesperus - Phosphorous" example in "On negation and necessities about concrete existence".

ReplyDeleteAny statement of equivalence (a=b), where the referent of the first term is x1, and the referent of the second term is x1 (i.e., where the two terms are referentially identical) is necessarily true, since it expresses an automorphism. We could add that the property wrt which the equivalence holds must be an appropriate one. "just as tall as" or the weaker "at least as tall as" will do as equivalence relation significances. Whether what is described in the statement exists out there in the world does not enter in to the judgment. "Given name - nom de guerre" may be risky, so 'Morning Star' - 'Evening Star' might be better (at least as big as").

JPL (the modality fan)

Pardon the late reply.

DeleteNo, 'Hesperus is Phosphorus' doesn't pose the same difficulty because it can be known a priori to be either necessarily true or necessarily false. The point of the Strohminger/Yli-Vakkuri example is that it is not like that, and nor is it implied by a proposition which is like that (at least not on an austere formal view of implication).