I’ve been in Geneva for about three weeks now, and I’ve got another three weeks left. Time has gone past quickly and I’ve been neglecting work a bit, but it doesn’t mean that I haven’t been doing philosophy. It’s about time that I start thinking about the two talks that’ll give here in December though, and since they are on modality, I thought I might make a few remarks about the topic. There will be a lighter post very soon with some photos from a hike that I did last weekend, but today it’s just hardcore philosophy I’m afraid!

Bob Hale (Sheffield): Possibilities

As it happens, about a week and a half ago we had a workshop which was exactly on modality (and the experience of time), namely the sixteenth eidos workshop. The first day was dedicated to modality, and it was certainly the more interesting for me, and the second was on the experience of time. I’ve posted photos from the workshop here. Although all the talks were interesting, Fabrice Correia’s was closest to my own research, so I will make a few comments relating to his talk ‘On the Reduction of Necessity to Essence’ here.

Those familiar with the topic will know that this will have something to do with Kit Fine’s influential paper ‘Essence and Modality’. The topic that I wish to bring up does not concern this exactly, but rather the hierarchy of different kinds of modality, specifically, metaphysical, conceptual, and logical modality.

Correia’s presentation of Fine’s view included one principle which I found problematic, namely the monotonicity principle, which says that if A is true in virtue of the nature of X and X is a subset of Y, then A is true in virtue of the nature of Y. According to Correia, this has the following consequence for Fine’s view: logical necessity is at least as strong as conceptual necessity, which is at least as strong as metaphysical necessity. The key here is the interpretation of ‘strong’. I had a chat with Correia and at first I thought that I must understand it differently from him. Bob Hale, who was also the workshop, defined ‘strong’ in his 1996 paper ‘Absolute Necessities’ as follows:

One kind of necessity, [box1], may be said to be stronger than another, [box2], if ‘[box1]p’ always entails ‘[box1]p’ but not conversely. Assuming the usual relations between necessity and possibility, this relationship will obtain if and only if [diamond1] is weaker than [diamond2], i.e. ‘[diamond2]p’ always entails ‘[diamond1]p’ but not conversely. I shall also say that [box1] is at least as strong as [box2] if the first half of this condition is met, i.e. ‘[box1]p’ always entails ‘[box2]p’.

Now, if I’ve understood correctly what Hale means by at least as strong as, and Correia says that he means it in the same sense, then saying that logical necessity is at least as strong as conceptual necessity, which is at least as strong as metaphysical necessity amounts to this: if p is logically necessary, then p is conceptually necessary, and if p is conceptually necessary, then p is metaphysically necessary. This is something that some people might indeed want to say, but in my understanding it is not what Fine wants to say, or what I want to say, or indeed, so I thought, what Correia wants to say.

Fabrice Correia (Geneva): On the Reduction of Necessity to Essence

Why is this? Well, if this were the case, then it appears that all logical necessities are metaphysically necessary, i.e. all things that are true in virtue of all logical concepts are also true in virtue of the nature of all things. This may seem fine, but it is incompatible with a certain intuitive understanding of necessity. What I mean is that, for me at least, something being necessary entails that it is true throughout the modal space. And the modal space, according to the Finean picture, is metaphysical modality (we may here ignore normative and natural modality, which Fine distinguishes from metaphysical modality). We can of course divide the modal space into smaller, proper subsets of metaphysical modality, which is what we do when we talk about logical and conceptual modality, but if we then say that something is logically necessary, we mean that it is true throughout the proper subset of metaphysical modality which concerns logical concepts. Now, we can certainly say that all logical necessities are a proper subset of metaphysical necessities, but it is misleading to say simply that all logical necessities are metaphysically necessary. How could this be when logical modality only concerns a proper subset of metaphysical modality — it can make no claims outside its designated realm.

So, I believe that what has happened here is that in the end Correia and myself share the same Finean picture about modality, indeed it seems as much from my discussions with him. However, the monotonicity principle causes unfortunate connotations. At the very least, we should not use Hale’s notion of strength here, as it is apt to drive us towards the problematic reading of the relationship between logical and metaphysical modality.

John Divers (Leeds): The Acquisition of (Warranted) Belief in Absolute Necessity

Quite independently of this confusion, there is a further problem here concerning metaphysical necessities which are not logically necessary, e.g. the proposition ‘all cats are animals’, as tt would seem to be the case that the proposition ‘cats are demons’ is logically possible, but not metaphysically possible. So in the Finean picture, there seems to be no room for such propositions. Correia did not offer much in terms of an answer to this problem, but my own solution is to simply exclude them from the modal space: they are pseudo-possibilities. Of course more needs to be said about the modal epistemology behind this picture, namely, how do we know which possibilities are pseudo-possibilities. I’ve said something about this in my previous post about Counterfactuals and Modal Epistemology, but I’d better not go into the topic here…

Another update will follow soon!

1. ttahko.net » Blog Archive » Varieties of Modality I says:

   December 12, 2009 at 11:54

   [...] Some Remarks about Modality [...]