RE: SUO: Logic and Ontology
Bill,
Re: your beer example.
You wrote" That's a big assumption. I have to think this through better but
if you
make this move then you're committed to something like Lewis' view where a
predicate like "Beer" applies to all the beer there is, anywhere, at any
time (thus extensional). On this view "Beer" can't apply conditionally to
individuals at worlds or at times."
When talking about extensionality as a basis for identity one needs to be
careful whether one is talking about it at the property or object level - or
both. Beer can be a mass or count noun - but in phrases such as "all the
beer there is" it seems to me to read like a mass noun. In this case,
following Quine and Lewis it would be a scattered object - and one could,
like them, treat identity for objects extensionally. However, as you clarify
in your second message, you are talking about 'bits of beer' - things not
stuff - so (I presume) about property extensionality.
Regards,
Chris
-----Original Message-----
From: owner-standard-upper-ontology@majordomo.ieee.org
[mailto:owner-standard-upper-ontology@majordomo.ieee.org]On Behalf Of Bill
Andersen
Sent: 06 March 2002 01:57
To: SUO
Subject: Re: SUO: Logic and Ontology
On 3/5/02 17:20, "Leo Obrst" <lobrst@mitre.org> wrote:
> Yes, I would agree that if you assume extensionality, as Bill suggests,
> you are nearly to the end of your chain, Matt. But many people have real
> problems with this assumpton.
>
> I too received this Axiomathes issue (and I too have a problem with the
> extensionality assumption), but have not yet read the Cocchiarella
> article (though I am usually sympathetic to his views). But I didn't
> think that was Lewis's view: geez, Bill, I thought nearly the opposite,
> will have to review. I just thought Lewis took a realist position wrt
> possible worlds.
That's true - about as real as you can get. But if you look at Counterpart
Theory, his quantifiers range over all the objects, not just the ones at a
world - it's a completely standard first-order theory so you don't have the
world-bound truth values of Kripke semantics.
What he does is have a special predicate for which things are at a given
world. So, all the beer for him is just all the beer - or the class of all
bits of beer. It's only that some worlds will have beer as parts of them
(for him if I understand correctly they literally are 4D parts) and some
won't. He deals with modal phenomena by introducing all of these possible
(excuse me - counterpart) beers, some of which correspond to the beer in the
actual world and some that don't.
.bill