Wolfgang Schwarz

Tex Test

I've set up a new server, so that now this blog should support LaTeX commands. As a test, here is what I take to be the most general version of the fixed Principal Principle:

Hm. The 'x' is a bit blurry.

Parts and Counterparts II

As usual, I ended up rewriting the entire paper when I just wanted to add some footnotes to deal with timetravel and fission. Here's the new version. I still believe there is something wrong with the conclusion (which I also still find dull), but at least the characterizations of Counterpart and Fusion Theory now look better to me.

Ned Update

Turns out that I mostly use my Ned editor for making and editing websites and web-applications nowadays. So I've just fixed some bugs (like the problem with tab characters) and added some features (like switching character encodings and a zip & download option).

Semantics for Time-Travelers

I'm somewhat stuck with the parts/counterparts paper. One of the problems is to find an acceptable semantics for time travel situations.

Part of the problem is that I'm often unsure what to say about these cases. I guess if time travel were more common, we would need some new linguistic conventions. Anyway, here are some sentences that seem true to me in the following scenario: Tina decides in 2025 to meet her younger self back in 2005. So at some time t in 2005, the younger Tina is in the living room and weighs 60 kg while the older Tina is in the kitchen and weighs 70 kg. Now, these all seem true to me:

Parts and Counterparts

I've written a little paper about the difference between theories on which ordinary things are fusions of parts located at various places, times, and worlds, and theories on which they instead have counterparts there. The dull conclusion is that there is no difference. I'm not sure I believe anything in there, and it's all quite rough, so comments are welcome: Parts and Counterparts (PDF).

Update 2005-03-08: Robbie Williams points out that my translation between Counterpart and Fusion Theory does not handle fission cases correctly. I should at least (following Lewis's translation scheme) say that names in the fusion language are indeterminate between all maximal eligible fusions of the corresponding counterparts from the counterpart language. But this is only a partial fix. I hope to come up with something better soon, though as I'm on the road for the next couple of days, that will probably have to wait until the weekend.

Atomism

Ordinary objects - persons, planets, rivers and tables - are unextended atoms. They occupy only one point of space at only one time at only one world.

At first sight, this might sound absurd. Don't ordinary things obviously exist at many different places, times and worlds? Isn't the Yangtze clean in Geladandong and dirty in Shanghai? Wasn't it clean in Shanghai in 1500? And isn't it clean in Shanghai now at some other possible world?

Fortunately, Atomism need not deny any of this. For even though the Yangtze is an unextended atom that strictly speaking only occupies a single point, it has many counterparts at other points. And these counterparts make all those statements true.

Metaphysical Modality and S5

Note to self: I sometimes say that metaphysical modality is of S5 type, when I should rather say only that it satisfies the characteristic axiom of S5, Mp -> LMp.

It isn't clear to me that metaphysical modality obeys all the S5 principles because it isn't even clear that it obeys T. One of the problems is what to say about Lp if p contains names of objects which may exist only contingently. The two most obvious proposals are: a) Lp is true iff p holds at all worlds where the named objects exist (in this sense, Hesperus is necessarily Hesperus, even though Hesperus exists contingently); b) Lp is true if p holds at all worlds (in this sense, Hesperus is not necessarily Hesperus, but it is necessary that if Hesperus exists then Hesperus is Hesperus). Either way violates T. On (a), let "F" express the property of coexisting with Hubert Humphrey; then "L(F(Hesperus) & F(Humphrey) -> F(Hesperus)) -> L(F(Hesperus) & F(Humphrey)) -> LF(Hesperus)" is false, even though it's an axiom of T. On (b), "L(Hesperus = Hesperus -> Hesperus = Hesperus)" is false, even though it's a theorem of T.

Missing Stages

According to the Stage View, ordinary objects are temporally unextended timeslices. "Ted sleeps" is true iff the present Ted-stage sleeps.

What if there is no present stage, as with "Socrates is wise" and "Socrates exists"?

The question is not what to say about "Socrates was wise" and "Socrates did exist". These are true because at some time in the past, there is a wise Socrates stage (see pp.27f. of Ted Sider's Stage paper). The problem is the tenseless "Socrates is wise".

Soames on A Priori Knowledge

I'm trying to catch up with Dave Chalmers's reading of Scott Soames's Reference and Description. I'm still at chapter 4, and my reaction to it is not quite the same as Dave's. (I began this entry as a comment over there, but it somehow grew way too long.)

Let's stipulate that "Lee" (rigidly) denotes the youngest spy (if there is one). Soames argues that if

Substitutional Quantifiers

Until recently, I thought that there are no quantifiers in ordinary discourse for which a substitutional interpretation is adequate, or helpful. I still think this is true for almost all cases, including quantification over fictional and intentional objects. But here are two cases where a substitutional interpretation looks ok.

First. The world can be completely described in precise vocabulary. There are no vague objects with irreducibly vague bounderies or heights or colours. Rather, for many terms, like "Mount Everest", it is indeterminate exactly which perfectly precise object they denote. But it is very natural to say that Mount Everest has vague boundaries. Instead of denying it, I'm inclined to offer some kind of reinterpretation, such as: there are different objects slightly differing in their boundaries between which "Mount Everest" is indeterminate; or: for no precise boundaries b is it true that Mount Everest has boundaries b; or: for some precise boundaries b is it indeterminate whether Mount Everest has boundaries b. All these are true, and all of them could be meant by "Mount Everest has vague boundaries".