Vetter (2015) Potentiality 1.2

Vetter, Barbara (2015). Potentiality From Dispositions to Modality. Oxford: Oxford University Press

 

1. Modality

The two familiar modalities: necessity (□) and possibility (◇)

Modal phenomena: (1) laws of nature, (2) essences, (3) the counterfactual conditional, (4) causation, and (5) dispositions

 

2. Reductive vs. Non-reductive approaches 

① A reductive approach: describe all of these phenomena in a language that is taken from outside the modal package and impose some hierarchy on the modal package.

David Lewis, for instance, analyses laws of nature in terms of a best system for the actual world, counterfactuals in terms of possible worlds and laws of nature, causation in terms of counterfactuals, and dispositions in terms of counterfactuals and causation. [4]

 

② A non-reductive approach: "It will not try to capture the elements of the modal package in terms of something non-modal, but it can impose a hierarchy on the package itself, understanding parts of the package in terms of other parts." [5]

(1) Williamson (2007b): possibility and necessity in terms of counterfactual conditionals

(2) Lange (2009):  logical to nomological necessities in terms of primitive counterfactual conditionals or ‘subjunctive facts’

(3) Fine (1994): necessity in terms of essence

(4) Stalnaker 2003: "possibility and necessity are (metaphysical or conceptual) primitives, with the help of which we can give an account of possible worlds, and that possible worlds in turn provide, in one way or another, the truth conditions for statements about the rest of the modal package" [5]

3. Localized vs. Non-localized Modalities

① The operators for the non localized modalities may be one-place operators (as in the case of possibility) or two-place operators (as with the counterfactual conditional); but their argument places must always be filled by an entire sentence [Formula]. Possibilities are possibilities that . . . .

② The operators for localized modalities, on the other hand, must have at least one argument for the object (or objects) [terms] to which the modality belongs, and another argument place for that which is intuitively the content of the modality, and which is most naturally expressed by a predicate. Thus we have:

...is essentially..., and...has a disposition to...

the first blank, in each case, requiring a singular (or plural) term to be filled, the second a predicate.

 

4. Troubles with Possible worlds

...it has generally been assumed that the localized ones can be defined in terms of them [the non-localized modalities]. The conditional analysis of dispositions and the modal account of essence are symptoms of that general tendency. Non-localized modality, in turn, has been thought about in terms of possible worlds: thus what is possible is simply what is true in some possible world or other. The crucial question then becomes: what are possible worlds? Are they concrete universes, spatiotemporal totalities just like ours, as David Lewis (1986a) has it? Or are they maximal (sets of) propositions (Plantinga 1974, Adams 1974), uninstantiated properties of the world (Stalnaker 1976), recombinations of actual properties (Armstrong 1989a), or mere elements of fictions (Rosen 1990)?

Possible Worlds를 쓰는 이유는 theoretical usefulness 때문임. 그러나 그러나 이 개념이 적절한 형이상학적 기반 위에 있는지 (또는 있을 수 있을지)는 의문스러움.

Possible worlds can be:

① concrete, as Lewis argued, or

② some kind of abstract entities, such as sets of propositions or uninstantiated properties

If, on the other hand, possible worlds are sets of propositions, we need some way to distinguish those sets of propositions that do from those that do not correspond to genuine possibilities; mere logical consistency is not enough. If abstract possible worlds are supposed to deliver a robust account of metaphysical modality, it is hard to see how they can avoid circularity; if not, then they are simply irrelevant to the metaphysical question of what possibility and necessity are. (See Williamson 1998 and Jubien 2007 for contemporary versions of this kind of criticism.) [6]

 

5. ‘Humean supervenience’

① The doctrine

All there is to the world is a vast mosaic of local matters of particular fact, just one little thing and then another.

We have geometry: a system of external relations of spatiotemporal distance between points. Maybe points of spacetime itself, maybe point-sized bits of matter or aether or fields, maybe both. And at those points we have local qualities: perfectly natural intrinsic properties which need nothing bigger than a point at which to be instantiated. For short: we have an arrangement of qualities. And that is all. There is no difference without difference in the arrangement of qualities. All else supervenes on that. [Lewis]

Possible worlds provide a viable way for the Humean to ‘outsource’ modality: it is still a matter of deeply non-modal facts; we simply need enough such facts. One Humean world does not provide modality, but many of them do. Thus the metaphysics of modality, for the Humean, becomes a metaphysics of possible worlds. [7]

②  The objection

(1) Why should we believe in Humean supervenience in the first place?

Lewis’s own stated motivation is ‘to resist philo sophical arguments that there are more things in heaven and earth than physics has dreamt of’ (Lewis 1994, 474).

Many philosophers of science now argue that the fundamental physical properties, those which make up the supervenience base, are not the Humean’s ‘qualities’, that is, quiddistic properties with no modal profile. Science, as Simon Blackburn and others have argued, ‘finds only dispositional properties, all the way [완전히] down’ (Blackburn 1990, 63; see also Molnar 1999, and Bird 2007). What physics tells us about a fundamental property, such as—for the sake of a, probably inaccurate, example—negative charge is how that property enables and disposes its bearers to react and interact with things that have the same or other fundamental properties. Physicists have nothing to say about any ‘underlying’ qualities or quiddities that are independent of such dispositional patterns, but such qualities are precisely what is required for the Humean’s supervenience base. In maintaining that there is more to the properties discovered by science, namely, a quiddistic nature, it is Humean supervenience that is guilty of supposing that ‘there are more things in heaven and earth than physics has dreamt of’. [8]

 

6. Dispositionalism

Dispositional essentialists, most prominently Ellis and Bird, hold that the fundamental properties in nature are (all or most of them) essentially dispositional: what these properties are is simply a matter of what they enable or dispose their bearers to do. If the world is irreducibly dispositional, it is irreducibly modal. There is, then, no need to outsource all modality to other possible worlds, and reason to hope that no such outsourcing is needed. [10]

The world as the dispositionalist envisages it, I said, is irreducibly modal. But the modality that it fundamentally contains is localized: it is the dispositions of objects to behave thus-and-so. It becomes natural, then, to use this local modality in accounting for other phenomena that are otherwise explained in terms of possible worlds. One suitable explanandum for dispositionalists has been the laws of nature, which are thought to be fully grounded in the dispositional essences of the properties that they concern (Ellis 2001, Bird 2007). Another is causation, for which there are currently different dispositionalist proposals on the table (Mum ford and Anjum 2011, Bird 2010, Hüttemann 2013). A third obvious candidate is the focus of this book: metaphysical modality. [10]