From owner-modality@LISTSERV.ARIZONA.EDU Wed Mar 31 00:29:40 1999 Date: Wed, 31 Mar 1999 00:29:04 -0800 Sender: "Philosophy 596B: Mind and Modality" From: David Chalmers Subject: Next week To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO For next week's meeting, we will focus on possible worlds. The readings should be in the purple folder by sometime Wednesday. They are Lewis, Possible worlds Adams, Theories of actuality Stalnaker, Possible worlds. Lewis, Selections from "On the Plurality of Worlds". These present three different ways of understanding the nature of possible worlds. Lewis argues that possible worlds exist in just the same way that the actual world does (modal realism, or concrete modal realism). Adams and Stalnaker argue that possible worlds should be understood as some sort of abstract objects, or as "ersatz" worlds constructed via a linguistic or propositional construction. (The last part of Adams on "world-stories" is particularly relevant.) The Lewis book selections defend modal realism in more detail, and give a critical discussion of some "ersatz" proposals. If you can, it might also be good to look at the Lewis book as a whole. This goes exhaustively into all sorts of issues here -- why modality is important (chapter 1), objections to his modal realism (chapter 2), and pros and cons of the various "ersatz" constructions (chapter 3). It's also a wonderful clear book to read. It's out of print, unfortunately, and too long to reproduce wholly here, so I will copy just parts of chapters 2 and 3. The chapter 3 material (which in essence can be seen as a response to the Adams and Stalnaker proposals) is particularly relevant for our discussion. We'll discuss those general issues in the first half of next week's meeting. In the second half we'll try to apply the issues in the general context of conceivable worlds, two-dimensionalism, etc. In particular, we will see if we can justify the claim that the space of ideally conceivable worlds exists in at least the sense that standard possible worlds exists (e.g. an "ersatz" sense). We'll talk about why such worlds might be needed; and we will see whether we can go through an "ersatz" construction so that this space of worlds makes coherent sense. This will correspond do what I say extremely briefly in Mind and Modality 2.9, (i) and (ii). It would help to look at that, and also at what I say re the need for conceivable worlds in 3.2 of "Materialism and the Metaphysics of Modality". If you can, think about how one might go about making up an ersatz construction (perhaps starting from concepts and the notion of apriority, and perhaps one or two other primitives) that will deliver the right results. In the meantime, on the mailing list this week it would be good to see a detailed discussion of some of the issues re scrutability and cosmic hermeneutics. E.g. Horgan, Byrne, Block and Stalnaker, my discussion, and any general thoughts you might have. We didn't get a chance to go over Block and Stalnaker exhaustively in class, so it might be particularly useful to hear any comments on the details of their paper. --Dave. From owner-modality@LISTSERV.ARIZONA.EDU Tue Apr 6 23:24:05 1999 Date: Tue, 6 Apr 1999 23:22:47 -0700 Sender: "Philosophy 596B: Mind and Modality" From: Erik A Herman Subject: possible worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO I have a question about possible worlds: A possible world is the set of stuff that is causally connected in space and time. How do you treat the effect of "consideration" of a possible world on the actual world. For example, this actual world is now different than it would have been had we not considered a possible world where there are talking donkeys. How is this reconciled? Erik H. From owner-modality@LISTSERV.ARIZONA.EDU Sat Apr 10 16:38:04 1999 Date: Sat, 10 Apr 1999 16:37:55 -0700 Sender: "Philosophy 596B: Mind and Modality" From: David Chalmers Subject: Re: possible worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO On Erik H.'s point re possible worlds: I think it's clearly true that a world where I'm thinking of talking donkeys is different from a world where I'm not. More generally, a world W1 where I'm thinking of world V1 is different from a world W2 in which I'm thinking of world V2. But this doesn't imply that there is causal interaction between V1 and W1. Rather, V1 and W1 have been the way they are all along! Still, there is a deep question about just how one can think about something that one can't causally interact with. This bothers quite a few people thinking about the epistemology of possible worlds. One can at least say in reply that the problem here isn't obviously worse than the problem in mathematics, where one can apparently think about the number 2 without causally interacting with it. Someone who believes that possible worlds are "abstract objects", like mathematical objects, might well hope that the two problems will have the same sort of solution (whatever that is). Lots of solutions have been offered, but I don't think any single solution has widespread acceptance. --Dave. From owner-modality@LISTSERV.ARIZONA.EDU Tue Apr 13 22:34:42 1999 x-sender: agillies@pop.u.arizona.edu Date: Tue, 13 Apr 1999 13:15:48 -0700 Sender: "Philosophy 596B: Mind and Modality" From: Anthony S Gillies Subject: truth conditions and conceivable worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO All, We ended last time by sketching the truth-conditions for modal sentences using a "conceivable worlds" semantics. Maybe I missed something. I thought the semantics should go something like the following: (*) Nec P is true_1 iff: for any conceivable world w, P is true_1 at w. (**) Nec P is true_2 iff: for any conceivable world w, P is true_2 at w. But (**) doesn't at all correspond to Dave's defiition (if I recall). I would have thought the above was the natural way to do things since it recursively calls truth_1 or truth_2 for non-modal sentences, which we already have worked out (the general sketch of the 2D framework does that). The problem is with (**). The semantics is supposed to hold out the possibility that the class of conceivble worlds is not co-extensive with the class of metaphysically possible worlds. But (**) makes appeal to conceivable worlds where P is true_2, and truth_2 is what some might call "metaphysical truth" (type-B materalists, e.g.). Combining that with (**), though, we get that there are no truths P such that Nec P is true_2. And this is awkward for conceivable world semantics. In fact, it might give someone reason to doubt that there is anything useful (apart from defeating materialism) in the semantics. On analogy with possible worlds semantics, conceivable worlds semantics needs the claim to usefullness. Fixing (**) might be problematics too: (**) is the natrual way of giving modal semantics, and changing only (**) without substantively changing (*) looks ad hoc. This points to another confusion I've been entertaining on 2D semantics. It's probably a little off topic, so we'll get to it in a week or two. But the main idea is to what extent the 2D semantics for terms meshes with the 2D semantics for sentences. In particular, in figuring the truth_1 of a sentence S, it looks like every term in S must be mapped to its referent_1. Likewise for truth_2. Are there sentences S for which the natural truth_1 conditions might depend on some term in S being mapped to its referent_2? Thony "Curious green ideas sleep furiously." From owner-modality@LISTSERV.ARIZONA.EDU Tue Apr 13 23:44:23 1999 Date: Tue, 13 Apr 1999 23:44:09 -0700 Sender: "Philosophy 596B: Mind and Modality" From: David Chalmers Subject: Re: truth conditions and conceivable worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO Thony wrote (it came through eventually): >We ended last time by sketching the truth-conditions for modal sentences >using a "conceivable worlds" semantics. Maybe I missed something. I >thought the semantics should go something like the following: > >(*) Nec P is true_1 iff: for any conceivable world w, P is true_1 at w. > >(**) Nec P is true_2 iff: for any conceivable world w, P is true_2 at w. > >But (**) doesn't at all correspond to Dave's defiition (if I recall). I don't remember exactly what I said last week. But looking at what you have here: it's not a million miles from what I would say, but I would change some details. In particular, I wouldn't put the left-hand sides as "'nec P' is true_1" and "'nec P is true_2", as the two right hand sides can have different actual truth-values for many P, but the left-hand sides cannot, at least at the actual world. (If a statement is true_1 at the actual world it is true_2 there, and vice versa.) So it's better to write the left-hand sides as "P is 1-necessary" and "P is 2-necessary", or "nec_1 P" and "nec_2 P", or some such. >I would have thought the above was the natural way to do things since it >recursively calls truth_1 or truth_2 for non-modal sentences, which we >already have worked out (the general sketch of the 2D framework does >that). For the reasons above, I think it's best not to think of 1-necessity and 2-necessity as the primary and secondary intensions of a single concept of "necessity". Rather, it's that the concept of "necessity" is ambiguous, and we need to disambiguate two distinct concepts. Probably these concepts are best regarded as not themselves having a deep 2-D structure -- it's not as if the notion of "necessity" (or "1-necessity" or "2-necessity") picks out different things depending on how the actual world turns out. At least, nothing in the 2-D considerations alone suggest that conclusion, though one might conceivably come up with other arguments for it. >The problem is with (**). The semantics is supposed to hold out >the possibility that the class of conceivble worlds is not co-extensive >with the class of metaphysically possible worlds. But (**) makes appeal >to conceivable worlds where P is true_2, and truth_2 is what some might >call "metaphysical truth" (type-B materalists, e.g.). Combining that >with (**), though, we get that there are no truths P such that Nec P is >true_2. And this is awkward for conceivable world semantics. I don't quite follow your claim at the end. Even with the semantics you suggest above, won't "2+2=4" and "water is H2O" be examples of truths P such that Nec P is true_2 (as P will be true_2 in all conceivable worlds)? But anyway, I think one has to be careful about equating truth_2 with "metaphysical truth". Actually, I'm not sure what "metaphysical truth" is, but I imagine the above comes to much the same thing as equating 2-necessity with "metaphysical necessity", so I'll consider that claim instead. It's true that on the 2-D picture, and on the modal rationalist view, 2-necessity (as defined here) and metaphysical necessity more or less coincide (at least on one plausible way of reading the latter). But on a view with strong necessities, the two may come apart, as such a view will have fewer metaphysically possible worlds than conceivable worlds. For example, it might just be that "the gravitational constant = XXX" is metaphysically necessary but not 2-necessary as defined here. On views with strong necessities, I suppose P will be metaphysically necessary is P is true_2 in all metaphysically possible worlds. Given that the spaces of conceivable and metaphysically possible worlds come apart on such a view, metaphysical necessity and 2-necessity (as defined above) will come apart similarly. >In fact, >it might give someone reason to doubt that there is anything useful >(apart from defeating materialism) in the semantics. On analogy with >possible worlds semantics, conceivable worlds semantics needs the claim >to usefullness. Fixing (**) might be problematics too: (**) is the >natrual way of giving modal semantics, and changing only (**) without >substantively changing (*) looks ad hoc. I don't quite follow this, but maybe you can elaborate. Again, I prefer to simply disambiguate the concept of necessity, rather than give it a 2-D modal structure. I think one can make the case for such ambiguity on independent grounds in any case, as e.g. we'll do this week in the material on subjunctives and indicatives. >This points to another confusion I've been entertaining on 2D semantics. >It's probably a little off topic, so we'll get to it in a week or two. >But the main idea is to what extent the 2D semantics for terms meshes >with the 2D semantics for sentences. In particular, in figuring the >truth_1 of a sentence S, it looks like every term in S must be mapped to >its referent_1. Likewise for truth_2. Are there sentences S for which >the natural truth_1 conditions might depend on some term in S being >mapped to its referent_2? Hmm, interesting. Again, a statement is true_1 at the actual world iff it is true_2 there. And a term's (actual) referent_1 will always be its (actual) referent_2 -- both are just the term's actual referent! It's only in non-actual possible worlds that these things come apart. But I suppose your suggestion might come to the possibility that to evaluate the truth_1 of S at some non-actual possible world, we need to consider the referent_2 of some term in S there, which would then depend on a posteriori facts about the actual world. The short answer, I think, is that this can't happen. Truth_1 is defined so that it depends only on facts about the world in question (plus a priori analysis). Some statements, e.g. "The actual president is Bill Clinton" might make reference to the actual world, but they can still be evaluated in a single-world way. E.g. to evaluate the truth_1 of the statement above at a world where George Bush is president, we consider that world as actual, and determine that if that world is actual, the statement is false. That's to say, one never needs to import the *actual* referent of "the actual president" in evaluating the truth_1 of this statement at world W. One only ever imports what the referent would be *if* W were actual. Of course one could try to come up with sentences that don't work this way, but I think that more or less by virtue of the way truth_1 is defined, the best we'll see is a pattern akin to the above. But I'm interested to see attempts, in any case! --Dave. From owner-modality@LISTSERV.ARIZONA.EDU Mon Apr 12 19:55:21 1999 Date: Mon, 12 Apr 1999 19:53:52 -0700 Sender: "Philosophy 596B: Mind and Modality" From: Rachael J Parkinson Subject: Re: possible worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO I have two questions- In seminar we were talking about other possible worlds which have the same history or are on the same time as our world (for example, consider a world where all the history up to this point is exactly identical with ours, only this seminar never took place.) It seems that this world is spatio-temporally related to ours? If so, should we consider it as another possible world or part of this world? One could even make the argument that this no-seminar world is causally related to ours if, from considering the other possible world, my actions are affected.( I imagine how unbarable life would be without this seminar and so decide that I should take it.) Likewise, we could imagine this type of causal interaction with respect to Erik H's talking donkey world. Finally, in response to Erik H, David suggested that the problem Erik poses can be compared to problems in mathematics... we can contemplate the number 2 without causally interacting with it. But, as Dave points out, this seems a more viable solution if we consider possible worlds as abstract entities, like numbers. Does the problem of how one can think about something one can't causally interact with remain if we consider actual worlds as literal, the way Lewis does? -Rachael On Sat, 10 Apr 1999, David Chalmers wrote: > On Erik H.'s point re possible worlds: I think it's clearly true that > a world where I'm thinking of talking donkeys is different from a > world where I'm not. More generally, a world W1 where I'm thinking of > world V1 is different from a world W2 in which I'm thinking of world > V2. But this doesn't imply that there is causal interaction between > V1 and W1. Rather, V1 and W1 have been the way they are all along! > > Still, there is a deep question about just how one can think about > something that one can't causally interact with. This bothers quite a > few people thinking about the epistemology of possible worlds. One > can at least say in reply that the problem here isn't obviously worse > than the problem in mathematics, where one can apparently think about > the number 2 without causally interacting with it. Someone who > believes that possible worlds are "abstract objects", like > mathematical objects, might well hope that the two problems will have > the same sort of solution (whatever that is). Lots of solutions have > been offered, but I don't think any single solution has widespread > acceptance. > > --Dave. > From owner-modality@LISTSERV.ARIZONA.EDU Tue Apr 13 01:20:52 1999 X-Priority: 3 X-MSMail-Priority: Normal X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Date: Tue, 13 Apr 1999 01:18:33 -0700 Sender: "Philosophy 596B: Mind and Modality" From: Brad Thompson Subject: Re: possible worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO In response to one of Rachael's questions: >I have two questions- In seminar we were talking about other possible >worlds which have the same history or are on the same time as our world >(for example, consider a world where all the history up to this point is >exactly identical with ours, only this seminar never took place.) It seems >that this world is spatio-temporally related to ours? If so, should we >consider it as another possible world or part of this world? I don't think that we should say that this other world is spatio-temporally related to ours. For one, that other world does not appear to be spatially related to this one. Further, I think it's best to restrict temporal relatedness to within-world events. I remember there was debate about this is seminar. But I don't find any problems with this restriction, nor does it really make sense to me to say that two events that are in different worlds occur at the same time in some absolute sense. Rather, when we describe two worlds that have the same history up until a particular time (within each world), events across worlds that we want to describe as "happening at the same time" ought to be described rather as occupying symmetrical locations in their respective world-histories. Brad From owner-modality@LISTSERV.ARIZONA.EDU Tue Apr 13 18:54:35 1999 X-Sender: agillies@pop.u.arizona.edu (Unverified) Date: Tue, 13 Apr 1999 18:36:23 -0700 Sender: "Philosophy 596B: Mind and Modality" From: "Anthony S. Gillies" To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO --============_-1288068678==_ma============ Content-Type: text/plain; charset="us-ascii" All, this is Josh's posting that he was unable to send: ___________________________________________ Some thoughts on possible worlds. Lewis distinguishes between two kinds of parsimony. A theory is qualitatively parsimonious if it posits fewer kinds of entities. A theory is quantitatively parsimonious of it posits fewer tokens of the kinds it posits. His claim is that people are interested in qualitative not quantitative parsimony. Lewis thinks that his realism about possible worlds is qualitatively, but not quantitatively parsimonious. "You believe in our actual world already. I ask you to believe in more things of that kind, not in things of some new kind." (p185) I'm curious whether that claim is really true. I don't know if this makes sense but see what you think. There seem to be two kinds of things that a Lewisian view posits that belief in only one actual world doesn't posit. First is logical space. On a one world view logical space is perhaps a concept or an abstract object or whatever. But whatever kind of thing it is, it is something we already have. It isn't clear this is true for Lewis. Logical space seems to at least be a set of super-universal laws that place constraints on how possible worlds can be. Consider the law of non-contradiction. If possible worlds are concepts or abstract objects then non-contradiction is just like other things which govern concepts or abstract objects in our world. But for Lewis this is a law external to our world or any other world. It has to be a different *kind* of law. If purely logical laws bug you then consider Lewis'es claim that all worlds have some kind of space time. Certainly, this isn't a logical truth. So if true it has to be a law which governs how possible worlds can be. This is a different kind of thing than the laws within our world. The second kind of thing that a Lewisian view posits that a one world view doesn't is entities that we are not spatio-temporally or causally connected to in any way. We have some kind of spatio-temporal connection to everything that exists in our world, including the world itself. Perhaps we have some logical or conceptual connections to other worlds and their contents. But there will be entities which exist yet I have no spatio-temporal connection to. This is a different kind of entity. I'm not sure how compelling this is but Lewis does seem to be a bit less parsimonious than he thinks. --============_-1288068678==_ma============ Content-Type: text/enriched; charset="us-ascii" All, this is Josh's posting that he was unable to send: ___________________________________________ HelveticaSome thoughts on possible worlds. Lewis distinguishes between two kinds of parsimony. A theory is qualitatively parsimonious if it posits fewer kinds of entities. A theory is quantitatively parsimonious of it posits fewer tokens of the kinds it posits. His claim is that people are interested in qualitative not quantitative parsimony. Lewis thinks that his realism about possible worlds is qualitatively, but not quantitatively parsimonious. "You believe in our actual world already. I ask you to believe in more things of that kind, not in things of some new kind." (p185) I'm curious whether that claim is really true. I don't know if this makes sense but see what you think. There seem to be two kinds of things that a Lewisian view posits that belief in only one actual world doesn't posit. First is logical space. On a one world view logical space is perhaps a concept or an abstract object or whatever. But whatever kind of thing it is, it is something we already have. It isn't clear this is true for Lewis. Logical space seems to at least be a set of super-universal laws that place constraints on how possible worlds can be. Consider the law of non-contradiction. If possible worlds are concepts or abstract objects then non-contradiction is just like other things which govern concepts or abstract objects in our world. But for Lewis this is a law external to our world or any other world. It has to be a different *kind* of law. If purely logical laws bug you then consider Lewis'es claim that all worlds have some kind of space time. Certainly, this isn't a logical truth. So if true it has to be a law which governs how possible worlds can be. This is a different kind of thing than the laws within our world. The second kind of thing that a Lewisian view posits that a one world view doesn't is entities that we are not spatio-temporally or causally connected to in any way. We have some kind of spatio-temporal connection to everything that exists in our world, including the world itself. Perhaps we have some logical or conceptual connections to other worlds and their contents. But there will be entities which exist yet I have no spatio-temporal connection to. This is a different kind of entity. I'm not sure how compelling this is but Lewis does seem to be a bit less parsimonious than he thinks. --============_-1288068678==_ma============-- From owner-modality@LISTSERV.ARIZONA.EDU Wed Apr 14 00:18:22 1999 Date: Wed, 14 Apr 1999 00:14:38 -0700 Sender: "Philosophy 596B: Mind and Modality" From: David Chalmers Subject: Re: possible worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO A few quick thoughts on possible worlds. In effect, Rachael and Brad bring up the question of how we are to define the notion of "spatiotemporally related". The problem is that if there are counterfactual worlds where I am doing something else now, it seems that my counterpart is in some sense temporally related to me -- he exists at the same point in time, after all. (Some philosophers, and maybe even Lewis, would deny that we can have this sort of "transworld identity" between points in time, just as they deny transworld identity for individuals, but I leave that point aside for now.) Intuitively (as Brad suggests), there is a stonger notion of spatiotemporal relatedness, such that for two entities to be spatiotemporally related they have to be in the same world, so that my counterpart won't count. But Lewis clearly can't just define spatiotemporal relatedness that way, as he wants to define "being in the same world" in terms of spatiotemporal relatedness, so the definition above would lead to a circle. So the question is whether we can find an independent definition of the stronger notion. One thing to try might be defining the relation in terms of the existence of a continuous path from A to B. Another thing would be to import causal relations here. A third thing would be to take this sort of spatiotempral relatedness as a primitive, as e.g. some do on the relational theory of spacetime. On such a theory, two beings or events in the same world might stand in the relation of e.g. A preceding B, or A being a certain distance from B, where these are a primitive sort of relation that only holds, intuitively, "within" a spacetime manifold. But maybe there are better suggestions here. All ideas are welcome. I think Rachael is write that on Lewis's view, the epistemology of possible worlds becomes more problematic. The analogy with mathematics works better for the ersatz theorist, as we're invoking abstract objects in each case. It's by no means obvious how we can have knowledge of abstract objects without causally interacting with them, but at least there is an intuition here that it's not entirly unreasonable. But in all other cases of concrete objects, it seems that knowledge requires something like causal interaction, or some other intimate epistemic acquaintance. In response, Lewis argues (pp. 110-12) that the relevant distinction isn't that between the concrete and the abstract, but rather that between the contingent and the necessary. Knowledge of the contingent requires some sort of acquaintance, but knowledge of the necessary doesn't. So I guess the debate comes down to which of these demarcations is most relevant for isolating the sort of knowledge that seems most clearly to require causal (or other) acquaintance. Any thoughts on Lewis's discussion here are welcome. Re Josh on Lewis on parsimony: I think these are good points. In response, Lewis might say that anyone who is serious about modality will need modal principles or "laws" governing logical space, so he isn't any worse off. Josh might say: it's one thing to have such laws governing abstract objects, another to have them governing concrete objects. Lewis might say: what's the big deal about concreteness? A modal law is a modal law. OK, I need modal laws governing concrete things, whereas you need modal laws governing abstract things, but that doesn't put us in obviously different boats. In any case, we already have modal laws governing concrete things (e.g. the principle of non-contradiction governs concrete things in the actual world). I think I tend to share Josh's intuition here, but it's a complex dialectic. Josh's second point is that Lewis needs concrete entities we're not spatiotemporally related to, and that's something new. I think Lewis would agree, but argue that this doesn't involve any new *fundamental* sort of thing. After all, we both have concrete objects, and spatiotemporal relations. Lewis just says something different about when objects stand in those relations. That's a nonfundamental "something new" analogous to me holding that there are swans in Australia where you deny it. And Lewis might argue that the principle of parsimony really on applies to fundamentals, rather than to these complex combinations. --Dave. From owner-modality@LISTSERV.ARIZONA.EDU Wed Apr 14 12:00:19 1999 Date: Wed, 14 Apr 1999 11:56:59 -0700 Sender: "Philosophy 596B: Mind and Modality" From: Josh Cowley Subject: Re: possible worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO First, I want to give a brief response to Dave on the parsimony issue. I don't think Lewis can can say that modal laws are modal laws be they laws for concrete or abstract objects. If possible worlds are concrete then modal laws exist independent of any one possible world. They are in some sense external to the worlds themselves. On the other hand, if possible worlds are abstract objects (or fictions, etc.) then the laws governing them will be laws within the actual world. Furthermore, there will presumably be other laws governing abstract objects of other sorts (ie. numbers), so modal laws will not be a new kind of thing. Turning to yesterday's discussion, I'm unclear exactly what the difference between and inscrutable truth and an open inconceivability is. Both, I take it, are cases that are negatively conceivable but not positively conceivable. Both are possible. Perhaps open inconceivabilities are things that are to weird to have a concept of, but I don't think we want to use "weirdness" as a formal distinction (though I admit it is an informal distinction). So what did I miss? Josh From owner-modality@LISTSERV.ARIZONA.EDU Tue Apr 13 01:20:52 1999 X-Priority: 3 X-MSMail-Priority: Normal X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Date: Tue, 13 Apr 1999 01:18:33 -0700 Sender: "Philosophy 596B: Mind and Modality" From: Brad Thompson Subject: Re: possible worlds To: MODALITY@LISTSERV.ARIZONA.EDU Status: RO In response to one of Rachael's questions: >I have two questions- In seminar we were talking about other possible >worlds which have the same history or are on the same time as our world >(for example, consider a world where all the history up to this point is >exactly identical with ours, only this seminar never took place.) It seems >that this world is spatio-temporally related to ours? If so, should we >consider it as another possible world or part of this world? I don't think that we should say that this other world is spatio-temporally related to ours. For one, that other world does not appear to be spatially related to this one. Further, I think it's best to restrict temporal relatedness to within-world events. I remember there was debate about this is seminar. But I don't find any problems with this restriction, nor does it really make sense to me to say that two events that are in different worlds occur at the same time in some absolute sense. Rather, when we describe two worlds that have the same history up until a particular time (within each world), events across worlds that we want to describe as "happening at the same time" ought to be described rather as occupying symmetrical locations in their respective world-histories. Brad