The Argument from Unreality

An additional argument for relative modality is rather obscure, and relies on some significant background assumptions and preferences. However, I will briefly run over the argument, in anticipation of some discussion that appears later. In chapter 2 I will consider the view that some logical pos- sibilities are “not real” or not “genuine” possibilities. Whereas a kind of possibility such as metaphysical possibility provides a genuine guide to how the world could be, the idea is that mere logical possibility falls short. E.g., it is a logical possibility that water not be H2O, but it is often assumed

to be made for logical modality being somehow “not real”, but if there is nevertheless a good account of logical modality to be had, and if we take other kinds of modality to be relative forms of logical modality, this may allow one to say that modality is not a genuine, real feature of the world. If one already has reasons for doubting the “reality” of modality, then one might find this line of thought attractive.

The argument goes:

1. Some logical possibilities are “not real” (therefore, logical modality is “not real”).

2. There is a good (non-relative) account of logical modality.

3. All other forms of modality (i.e. non-logical (alethic) modalities) are relative forms of logical modality.

4. Therefore (alethic) modality is not a genuine, real feature of the world. (3) is just the relative modality view. (2) is a condition on making the relative modality view viable, as was mentioned above.

The view that some logical possibilities are not genuine possibilities, (1), has become fairly common, based on the thought that overly restrictive ne- cessities, such as narrow logical necessities, should be counted as necessities “in name only”.

But those ‘possibilities’—such as the austerely logical possibility that there are male vixens—are possibilities in name only, not real or genuine possibilities at all. (Hale, 1996, p. 100)

The essentialist is simply at pains to maintain that any logical possibilities outside the domain of the metaphysically possible have no bearing on the ways the world might be. Such merely logical possibilities are possibilities in name only. (Shalkowski, 1997, p. 49)

At first glance, it appears that logical necessity should remain unaffected: one certainly still expects logical necessities to be true, and hence to give a reliable guide to ways the world must be. However, one may begin to doubt whether we can call logical necessity “real” if we allow that logical possibility and necessity are interdefinable as duals, i.e. p ⇔ ¬♦¬p and ♦p ⇔ ¬¬p. If it is logically necessary that p just when it is not logically possible that ¬p, and we have agreed that logical possibility is not a genuine guide for ways for the world to be, why should we be confident that logical necessity thus described is a “genuine” modality?

It is still not clear why logical modality’s failing to be “genuine” in this way should render it impotent to inform accounts of other kinds of necessity.

E.g., one might give an account of logical modality in terms of something like the laws of thought: rules for correct thinking, or norms against which one’s activity is subject to evaluation if it is to count as thinking at all.23 It is not clear why one would expect a kind of modality based on such a general notion to provide a guide for ways the world could be. Thinking a certain thing may be perfectly permissible according to these standards, but something more seems to be required to ensure that such a thing could exist: e.g. thinking about water which is not H2O avoids the vice of contradiction,

but whether or not there could be such a thing might also depend upon facts about substances.

We can now see how this line of thought relates to (4). One might be reluctant, for independent reasons, to take modality tout court to be a genuine, objective, mind-independent, robustly real feature of the world. Things such as modal properties, modal facts, possible objects and the like certainly have an air of mystery. What is their nature? How can we gain epistemic access to them? If I perceive that Tibbles is a cat, and Tibbles is necessarily a cat, do I also perceive Tibbles’s necessary-cat-hood, or just his cat-hood? One way to resolve these questions is to deny that there are such modal things, and explain modality in a different way. Now, if one endorses (1), that logical modality is “unreal” in some important sense, and one holds a relative view, encompassing (2) and (3), then one will have a strategy for reducing all (or at least all alethic) “real” kinds of modality to mere logical, non-real modality. Something like, e.g., natural necessity will still count as real insofar as the propositions which follow from laws of nature, say, do have a bearing on ways the world can be, however, the modality in this is not strictly a real phenomenon, but only borrowed from logical modality which does not itself have such bearing on the world. One could say that the common core shared by all kinds of modality is logical modality, which cannot provide a genuine guide for ways for the world to be alone, but which can be relativized to propositions about the world such that their logical consequences and compatibilities are able to chart so-called “real” possibilities.

Again, I must stress that this is clearly not a conclusive argument. How- ever, given a certain agenda, and the assumption that logical modality is not a genuine or real kind of modality, one should be motivated to explore a relative theory of modality.