Wolfgang Schwarz

Armstrong's Number-of-Parts Essentialism

Here's an odd passage from Armstrong's A Combinatorial Theory of Possibility, p.116:

[Hume's Distinct Existences Principle], as we shall uphold it, may be stated thus:

If A and B are wholly distinct existences, then it is possible for A to exist while no part of B does (and vice versa).

The principle applies straightforwardly to individuals, properties and relations. [...]

It is interesting to notice that the converse of Hume's principle also seems to be true:

The actual number of planets

Robbie has some interesting posts about rigidity. That made me wonder about "the actual number of planets", which no longer denotes the number 9 now that Pluto doesn't count as a planet any more. So what should we say?

1. "TANOP" rigidly denoted the number 9 last year and rigidly denotes the number 8 this year. (-- Even though the astronomical facts haven't changed in any relevant way!)
2. "TANOP" always rigidly denoted the number 8. (-- So Quine was wrong, but not because he got the astronomical facts wrong, but because he didn't know what he meant by "planet"; in fact, til last week, nobody ever knew what they meant by "planet"!)
3. "TANOP" changed its meaning in 2006. (-- So when we say that the number of planets is 8 we don't disagree with Quine when he said that the number of planets was 9!)

I think the third option is the only credible one. Would people with sympathies for reference magnetism go for the second? (If you would, do you think it's possible that the members of the IAU, who voted about the new definition last week, might have got the definition wrong?)

Causal Descriptivism and Deferential Descriptivism and Meta-Semantic Descriptivism

*) Oskar Minkowski discovered that dogs whose pancreas is removed develop the symptoms of diabetes.

Suppose this is the first time you've heard the name "Oskar Minkowski". Cases like this are good candidates for causal descriptivism. According to causal descriptivism, my utterance of (*) is true iff there is a person standing at the origin of a certain chain of communication leading to my present use of "Oskar Minkowski", and this person discovered that dogs whose pancreas is removed develop the symptoms of diabetes. This comes close to many people's intuitions about possible cases.

Luminosity Everywhere

In July, I tried to show that Williamson's argument against luminosity fails for states that satisfy a certain infallibility condition. I now think that (for basically the same reason) Williamson's argument fails for any state whatsoever, including knowing something and being such that it's raining outside. (The latter of course isn't luminous, but this is not established by Williamson's argument.)

Quiddistic Knowledge, Quiddistic Belief

In their contributions to Lewisian Themes, Rae Langton and Jonathan Schaffer both argue that quidditism -- the claim that possible worlds may differ only in which intrinsic properties play which causal/nomological roles -- does not entail skepticism about intrinsic natures because standard replies to skepticism about the external world carry over to skepticism about intrinsic natures.

But it seems to me that there is an important difference: if quidditism is true, we not only lack knowledge about intrinsic natures, but also any beliefs about them.

Kripke's (Alleged) Argument for the Necessity of Identity Statements

I have often encountered in articles, talks and classes the following argument for the necessity of true identity statements, always attributed to Kripke:

1) a = b (assumption)
2) a = a
3) a = b (from 1, 2 by Leibniz' Law)

The argument is no good, and I think it is very doubtful that Kripke ever endorsed it.

Back home

On top of the Flüelapass

I'm back. Still not sure about the errors; something seems to be leaking memory here. I've turned a few things off, let's see if that helps.

Error Messages

Apparently something's wrong with my server causing it to randomly deliver 403 errors from time to time. I'm on my (roundabout) way back to Berlin and will investigate when I've arrived, probably on Monday. Until then apologies for the inconvenience.

It's the time of year again

I'm about to take the night train for my annual bike trip through the Alps. I will have internet access tomorrow, but then I'll be unreachable for about a week.

Nomic Facts and the Future

Suppose some thing x turns F, and a little later some other thing y turns G. x is the only F throughout history, so on a Humean account of laws of nature, it may well be just a coincidence that y's being G followed x's being F. Suppose it is.

But now consider another world just like this one except that in the far future, lots of G-turnings follow lots of F-turnings so that in this world, it is a law that whenever something turns F and another thing is suitably related, then that other thing turns G. In such a world, x's turning F caused y's turning G.