Friday, May 18, 2007

Re-characterizing realism

Let’s call any sentence in which a modal word such as “possible”, “necessary”, “impossible”, “can”, “cannot” etc. plays a decisive role in determining the truth of that sentence a “modal sentence”.
A modal realist(MR) would subscribe to the following:
a) There are modal sentences.
b) The truth values of some modal sentences are fixed by the behavior of something(s) that is not both actual and concrete. (call these things m-entities)
c) M-entities exist.

A genuine modal realist (GMR) would add the following:
d) Some m-entities are concrete

An abstract modal realist (AMR) would add the following:
e) No M-entities are concrete.

Note that (d) -> (f)
(f) Some m-entities are non-actual

And that (e) is compatible with (g)
(g) All m-entities are actual

Note that (d)-> ~(e) and (e) -> ~(d), thus GM and AM are exclusive. Note also that ~(d) -> (e) and ~(e) -> (d), thus GM and AM are exhaustive.

A couple things are worth noting here. If we're speaking of possible worlds (for example), the m-entities would be all merely possible worlds. I'm not trying to parse out what different theories think of the actual concrete world (and actual concrete objects), since that is trivial (I hope) and would make the characterization needlessly confusing.
It may seem that (b) makes (c) redundant, but I threw (c) in to exclude noneism.
The versions of abstract realism he mentions in the book still fall under AMR under my characterization. In addition, Soames would count as an AMR under my characterization.
A fault of this characterization is the extremely vague notion of a "modal sentence" I employed. I'm still kind of fuzzy on the whole relationship between everyday english usage and the more strict philosophical talk. If only english had boxes and daimonds!


Dan said...

It's also worth noting that this account doesn't commit a realist to a reductive account of the meaning of modal sentences (although one is free to provide one). Thus, those who like to take modal words as primitive are free to do so.

Adam Murray said...

I'm sorry this is so long. It looks even longer after Dan's tidy formulation. I agree largely with Dan's presentation. I thought I would try and draw a couple of distinctions which would allow us to separate (under the heading of genuine modal realism) both Lewisian modal realism (LMR) and modal realism with overlap (MRO).

In order to classify the different possible realist positions across logical space, it seems necessary to say something about the following:

Fully Unrestricted Quantification (UQ):Roughly, we may say that our quantifiers are fully unrestricted iff they range over absolutely everything that exists. This formulation is neutral between (UQ1) and (UQ2):

(UQ1): The domain of fully unrestricted quantification is coextensive with the domain of what actually exists.

(UQ2) The domain of what actually exists is a subset of the domain of fully unrestricted quantification.

Possible Worlds (PW):
Here there seem to be at least three distinct formulations of a possible world that seem relevant to characterizing the views:

(PW1): w is a possible world iff (i) w is a concrete object, (ii) every part of w is spatiotemporally related to every other part of w, (iii) no part of w is spatiotemporally related to anything that is not a part of w. The actual world is a possible world.

(PW2): w is a possible world iff (i) w is a region of space-time, (ii) every part of w is spatiotemporally related to every other part of w, (iii) no part of w is spatiotemporally related to anything that is not a part of w. The actual world is a possible world.

(PW3): w is a possible world iff (i) w is a property, state of affairs, world-state or proposition, such that (i) w is maximal, (ii) w is complete. The actual world is a possible world.

Concrete Existence at a World (CE):

(CE1): Concrete objects are world-bound. No concrete object exists at more than one possible world.

(CE2): Concrete objects are not world-bound. A concrete object exists at (or is wholly present at) more than one possible world.

It also seems relevant to characterizing the views to say something about:
(i)the semantics of the expression ‘actual’ (A).
(ii)Ontological “seriousness.” (S)

(A)An utterance of the expression ‘actual’ is an indexical: it depends for its reference on the circumstances of its utterance. The relevant circumstance of utterance for the term ‘actual’ is the world where the utterance is located. An utterance of ‘actual’ at any world w is such that it refers, at w, to that world w itself.

(S) For any world w, and any object o and property F,if o has F in w then o exists in w.

If these considerations are correct, then it seems like we can characterize the different realist positions as follows:
i) at least two variations of genuine modal realism:

Lewisian Modal Realism (LMR): (UQ2), (PW1) and (CE1) + (A), (S)

Modal Realism with Overlap (MRO): (UQ2), (PW2) and (CE2) + (A), (S)

And (ii), abstract modal realism (AMR): (UQ1), (PW3), and (CE2) + (S)

This formulation of AMR seems to capture both the Plantingian and Kripkean forms of AMR, as well as the versions of AMR from Stalnaker and Soames.

Chris Tillman said...

On pp. 21 of "Modal Realisms", Kris McDaniel introduces a view and does some head-scratching over whether it's a possibilist view or an actualist view:

How would the view be characterized on your proposals?

(A side note about this whole issue of characterizing GR, AR, etc: I don't think much hangs on what we decide to call any particular view, but it is important to think some about which views there are and about what theses entail what. Note that one of the complaints with Divers was that he characterized GR and AR in terms of two general theses that bore no interesting logical relationship to each other; thus one could combine either of the theses with one of the theses of the other and obtain a new view not considered by Divers. I think it's important to recognize, in light of this, that even if all of his arguments about GR and AR are sound, no general conclusion immediately follows about realism in general since there are realist views other than the ones he's considering.)

Chris Tillman said...

Check out the beginning of Bricker's "Island Universes and the Analysis of Modality" for an objection to Dan-style characterizations:

Chelsey said...

Opening remarks:

First, as per Chris' instructions I'm posting this cold, i.e. without looking at the other posts. So, my apologizes if I repeat anything already written.

Second, this was a lot harder than I expected! So, if anything is egregiously wrong let me know. It seems as if definitions and clarifications (which is my forte and all...) are needed for every second word and can be even further defined ad infinitum.

I'll start with a general defintion of realism, then work my way in, as it were.

Realism: when unrestricted first order quantification (here I make no stipulation on the kind of quantification, just that there is quantification of some type going on) ranges over something that exists (either merely, possibly, or necessarily).

This seems to be as general of a definition for realism that one could make.

So on to the genuine and actualist realist positions. As an N.B. I'm going to make the balls out definition for both, and then further define and blither about the components of them after... gulp!:

Genuine Realism: when unrestricted first order quantification ranges over the domain of individual(s) (or PWs) that exist. The domain can consist of individual(s) that are / could be either:

concrete + actual
concrete + non-actual
non-concrete + actual
non-concrete + non-actual

Actualist Realism: when unrestricted first order quantification ranges over individual(s) (or PWs) that exist. These individual(s) are / could be either:

concrete + actual
non-concrete + actual

Definitions of concreteness and actuality (big job which merits it's own blog entry, so I'll try my best with the help of the common OED definitions) of an individual(s):

To say that an individual(s) is concrete, is to say that an individual(s) and / or the properties it instantiates can or could be poked with my hand or with a proposition. “Existing in a material form; real.” (feel free to jump down my throat about poking with propositions, but I couldn't think of any other way to define concreteness that is as general, yet distinctive enough to capture what I wanted).

To say that an individual(s) is actual, is to say that an individual(s) and / or the properties it instantiates can or could be quantified over. It is “existing in fact; real. ... [to exist in] actual reality as opposed to what was expected or intended.”

To sum-up(ish) it seems that the distinction I'm making between GR and AR is what is being quantified over. In the case of GR it is over the domain, in which case the individual(s) can be either concrete or not, and / or, actual or not. Whereas for AR it is the individual(s) themselves that are being quantified over, so they must be actualized (or merely possibly actualized) so that quantification is not vacuous. So, GR and AR are both realisms because they are talking about doing something (quantifying) over something (either individual(s) or their domains) that exist (in whatever sense you wish to define it).

Just as a side note... I do realize that the above definitions, or more justly for Realism itself, begs the question as to what would would be defined as a non-realist position. My conclusion, “is not much...”.

John Dyck said...

I feel very silly guys. I posted this as its own post since I was in a rush and hadn't noticed that everyone else had posted their own formulations here. So mine follow.

Over the weekend, I worked on giving stipulated definitions in terms of truthmakers. But I found out this morning reading Ch. 3 of Divers that it's difficult to give an account in terms of truthmakers, so I am sure this account isn't maximally awesome. Still, here goes:

Realism: Modal sentences have truth-values in virtue of the existence of truth-makers for some modal claims.

Genuine Realism: There exist multiple concrete worlds (concrete worlds besides the actual one) which serve as the truthmakers for modal claims. (The modal terms possible ( <> ), actual, and necessary ( [] ) can then be given for any proposition P and its truth within worlds. P is true in the actual world = actually P. P is true in some possible world = <> P. P is true in every possible world = [] P.)

Actual Realism: Facts about the actual world serve as the truthmakers for modal claims, [whether these facts are taken to consist of either: different combinations of actual properties, as in combinatorialism; or different kinds of complex properties, as in nature realism; or facts about maximally consistent propositions, as in world-book actualism].

It seems as though one problem with my account is this: intuitively, Plantingian realism (the view that possible worlds are nonactual states of affairs) should be a kind of actual realism. But in order for my account to accomodate it as such, I'd have to say that nonactual states of affairs are facts about the world. I'm unfamiliar with the position, but is that what Plantinga thinks? Perhaps I've gotten the view wrong, since he clearly seems to be an actualist. If not, then perhaps there is some clever maneuvring that can be done to allow for Plantingian realism within Actual Realism as I've given it, but I can't think of it.

Additionally, the absence of Plantingian Realism among my collection of Actual Realisms seems to be a point in favour of Dan's account, since he can allow for Plantingian Realism.

And, it seems like non-actual combinations of properties in the world aren't what we would call facts about the world. (They seem closer to what we would call falsehoods.) So it seems as though my definition excludes combinatorialism as well.

But a Dan-like revision of the thesis might help:

Abstract Realism': Non-concrete properties or entities in the actual world serve as the truth-makers for modal claims.

AR' changes the conditions of modal truthmakers from some sort of relation to an existing state of affairs to already-existing properties, which seems more profligate. Still, it does a better job of allowing for all the kinds of abstract realisms which Divers and Dan allow for.