Suppose theory 1 says that entity x has certain properties, and theory 2 says that entity y has those properties. If we believe both theories, should we conclude that x=y?
It depends. Sometimes we not only should but must conclude that x=y, for example when theory 1 says that x is the planet Venus and theory 2 says that y is the planet Venus. In other cases, there is little reason to draw the conclusion, as when the theories merely say of x and y respectively that it is some planet or other. In yet other cases, the conclusion can be motivated by methodological considerations. For instance, whoever first realized that Hesperus is Phosphorus probably realized that the identity makes for a simpler overall theory.
I just realized that I have inconsistent attitudes towards ontologically dependent entities, that is, entities x such that for some contingently existing entity y, i) necessarily, if x exists so does y, and ii) x and y are not parts or subsets or elements of each other. On the one hand, I don't believe that there are many such entities, except perhaps holes and borders. On the other hand, I also don't believe in general restrictions on the counterpart relation, or, perhaps equivalently, in restrictions on cross-world fusions of individuals. It follows that for any old property any world-bound thing has at our world, there is a thing which has this property essentially. For instance, there is somebody who leads exactly your life but who, unlike you, is essentially such that the cup in front of me is now empty. This somebody is a dependent entity: it can only exist if my cup does.
The other hand seems so obvious to me that I fear I must give up the one hand: there are lots of dependent entities. I can still say that they are not ordinary things, and that it is very hard or even impossible to refer to most of them (individually, of course -- I just managed to refer to them collectively). But still they exist. Hm.
One of the three other things I've been working on is Ned, a kind of web-based editor and file-manager. There are several reasons why I need this. One is that I often want to edit files on a server while I am at other places like the university where no (S)FTP or SSH client is installed. Another is that most of the servers I work with do not allow SSH access, so even if I only want to change a single character in a file, I have to open an FTP client, download the file, open an editor, change the character, save the file, and upload it again. Ned makes this much easier. Moreover, Ned also supports some filesystem operations (like copying files and recursively deleting folders) that are not supported by common FTP clients.
Hello, I'm back from wherever I was. Happy new year everybody!
In the train I wrote a few more notes on haecceitism and rigidity and physicalism and all that. I might blog them later so that I don't lose them. I also have to write applications for dissertation grants. Perhaps I should also start writing the dissertation itself. And then there are all those programming projects: I really need to improve my blogger (even more urgently now that it has been embarrassingly mentioned at various (1 2 3 4 5) blogs), and continue with the new tree prover. Today (or rather tonight) I made some not so urgent but simpler improvements to Postbote (mostly to do with encodings, but you might also notice that bouncing mails now correctly bounce back to you). I also have three new little things in the making that I hope to finish soon. One of them has something to do with philosophy, though I'm not quite sure if it's legal. Other people also want me to work on their webpages, as always. And I still haven't finished setting up my Linux system (the sound is obscurely missing). That all sounds really nice -- except that my main plan for 2004 was to get (a life and thereby) rid of RSI...
Here comes the solution to this year's Christmas puzzle:
First, is the story in the museum true or false? The crucial question is whether the last sentence in it is true. It goes:
*) If the story is true, the oracle finds out that it is.
Under what conditions is (*) false? It is false iff i) the story in the museum is true, but ii) the oracle doesn't find out that it is. On the other hand, since (*) is part of that very story, if (*) is false, the story is also false. So if (*) is false, the story is both true and false. So (*) can't be false.
The Museum of the Myth is not very comprehensive. In fact, it only contains a single story:
The Museum of the Myth is not very comprehensive. In fact, it only contains a single story. The story is not particularly exciting. Moreover, some people wonder whether it is actually false. If not, it would of course be incorrectly classified as a myth. So one day, the oracle is asked about the story. Luckily, the oracle is quite reliable: if the story is true, it undoubtedly finds out that it is.
The story is not particularly exciting. Moreover, some people wonder whether it is actually false. If not, it would of course be incorrectly classified as a myth. So one day, the oracle is asked about the story. Does it find out whether it is true?
If haecceitism is true, materialism is false. For if haecceitism is true, there is a world w just like ours except that you and I have traded places. By that I don't mean that in w someone with my origin or my DNA or my soul leads a life quite like yours. No, haecceitism holds that it is possible for us to trade places completely, so that in w not only my life is just like your actual life, but also my origin, DNA and soul are just like your actual origin, DNA and soul. w and our world do not differ in any qualitative respect at all. They differ only in facts that essentially involve you or me, such as the fact that in w it's you who is writing this posting. Whatever 'physical' means, it is clear that the physical facts are not of this kind. That's why materialism is false if haecceitism is true: Materialism demands that there is no difference at all between our world and any minimal physical duplicate of it.
Geoff at Too Much Text points out that the implausible hyper-essentialism implied by Kripke's account of rigidity can be avoided by adopting radical anti-essentialism, the view that there are no non-trivial (qualitative) essential properties at all. On this view, even though there is a precise boundary between a thing's essential and non-essential properties, the boundary is not very mysterious because it classifies virtually all properties as non-essential.
I want to write something about rigidity in the philosophy of mind. But first I have to say more about rigidity. (Apologies in advance: this is all going to be rather basic. But I'll need it, and I found that many people disagree with it.)
Recently I argued that the assumption that ordinary proper names are rigid designators leads to an implausibly excessive form of essentialism. But I don't want to deny the useful distinction between rigid and non-rigid designators. That is, in a sense I do believe in rigid designators. But they are not quite what rigid designators are usually supposed to be.
In my last post,
I said that I do not believe that every extended thing must have parts. Sam disgrees, arguing that whenever something is extended over length h, we can restrict our attention to a part of it with length h/n for any n < h.
I do agree that all ordinary extended things have parts. And I do agree that extended things without parts are really very strange. I'm just not sure that they are impossible.