New Jersey Necessity

One challenge to the kind of relative modality view I want to endorse has been raised by Rosen (2006), who complains that what I am calling contrived necessities are not rightly called “necessities” at all.

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The trouble is that most such ‘restricted necessity operators’ do not correspond to genuine species of necessity. Let NJ be the complete intrinsic truth about the State of New Jersey, and say that P is NJ-necessary just in case NJ strictly implies P. It will then be NJ-necessary that Rosen is in Princeton, but NJ-contingent that Blair is in London. But of course we know full well that there is no sense whatsoever in which I have my location of necessity while Blair has his only contingently. So NJ-necessity is not a species of necessity.

The moral is that one cannot in general infer, from the fact that a certain consequence (φ → P ) holds of necessity, that there is any sense in which the consequent (P ) holds of necessity. (If there were then every proposition would be necessary in a sense, even the contradictions.) (Rosen, 2006, p. 33)

Rosen argues that in the case of contrived necessities, there is no such sense of necessity, so any account which allows for contrived necessities must be wrong.

Rosen’s point is in conflict with the kind of arguments discussed earlier, such as those in Kratzer (1977), which draw on the multiplicity of “must”s in our language use. The point was that there are so many different meanings we can give to words like “must” and “can” that we need to give the words a relative semantics to accommodate such a profusion. In contrast, Rosen’s argument is based on an assumption that we have only a few senses of necessity, which do not stretch far enough to accommodate notions such as NJ-necessity. Who is right? Can we imagine a plausible situation in which someone would genuinely wish to assert something of the form, “In view of the complete intrinsic truth about the State of New Jersey, it must be that p” or “In view of the complete intrinsic truth about the State of New Jersey, it can be that p”? Here are some suggestions:

• Suppose that the inhabitants of New Jersey happen to be rather tra- ditional, and often have cold heads, resulting in the fact that everyone in New Jersey wears a hat. So it would be NJ-necessary that everyone wears a hat. One can imagine a newcomer to the state looking around at first, and saying to himself, “I must wear a hat”. This depends only on truths about New Jersey (e.g. it does not draw upon truths about Ohio), and it does not obviously seem to be a wider kind of necessity (it might be true in New Jersey that necessarily 2 + 2 = 4, but we would not usually say that with NJ-necessity in mind).

• New Jersey is an entity which is not independent of human society, e.g. its borders were determined by us, and the fact that it is a state also depends upon us. This suggests that we can include the laws of New Jersey in the complete intrinsic truth about New Jersey. If there is a

law unique to New Jersey, then any modal statements drawing on that law (“You must not. . . ”) could be described as invoking NJ-necessity. • I am writing a play, partly set in New Jersey. In my play, I want to hold true anything to do with the complete intrinsic truth of New Jersey, but I don’t care about anything else being accurate. I don’t have any particular plan for what kind of situations I want to have happen, as long as I respect New Jersey facts. Whilst writing one scene I say to myself, “Rosen must be in Princeton (given the complete intrinsic truth about New Jersey), but in that other scene, Blair can be in Paris”.

Even if one can describe strange circumstances in which rather contrived senses of “must” can be found, what about the most arbitrary cases, where we might define a kind of necessity as relative to three random propositions? Surely there is no intuitive sense of necessity we can bring to bear here? This forces one to look again at Rosen’s objection.

Rosen finds the conclusion that every proposition is necessary in some sense to be unacceptable, and so concludes that a relative modality account is wrong. However, it is open to the relative modality theorist to simply agree that yes, most propositions are necessary in some sense, but perhaps in a very uninteresting sense. Kinds of necessity such as necessity relative to truths about my left shoe together with truths about velcro can be dismissed as likely to be uninteresting, because the set of propositions to which they are relative is not an interesting grouping. But this is still a kind of necessity. As for every proposition being necessary, including contradictions, it is not clear what Rosen has in mind. Presumably he has in mind the idea that every proposition follows from itself, even contradictions. I have discussed problems arising from inconsistent sets of propositions above: at least this case should not occur for any alethic necessity.

The relative modality theorist might also diagnose Rosen’s worry as be- ing, not about necessity, but about what makes a kind of necessity count as non-contrived. Rosen is probably right to say that there is no non-contrived sense of necessity in which he has his location of necessity while Blair has his only contingently. But this is a claim about non-contrived necessities, and there are two parts to this notion: necessity, and being non-contrived. On the relative modality view, it seems that our familiar notions of necessity— metaphysical, natural etc.—are in danger of losing some kind of special status. A stark way to put (the widest version of) the view is that there is only logical modality; any other purported kind of modality is merely logical modality, relativized to some propositions. To raise our familiar notions out of the mire, we can tell a story about why they, as opposed to other shadows of logical modality, are more important. E.g., physical modality is special because it is relative to physical laws, which constitute an important class of propositions, or because it provides a reliable guide to how things can

and must be in the physical world. On the relative modality view, relative necessity becomes such a weak notion that the more important feature of a kind of necessity is really the operator Ψ applying to ϕ (see section 1.1.5 p. 25). Rosen mistakes the lack of a good story to tell about the complete intrinsic truth about New Jersey as the lack of any necessity.

It should be added that, after all, Rosen has not definitively shown that there can be no good sense for even a kind of necessity which is relative to 3 randomly-selected propositions. He has just pointed out that it is difficult, and so we tend to assume that there is none. Who is to say that one day things won’t be such that NJ-necessity, or pqr-necessity, develops into an important sense of necessity? The relative modality view at least has room to accommodate this kind of eventuality. Such necessities may always be available, but it is only when the defining predicate of the propositions to which they are relative gains prominence that they will be brought to the fore.