Hi John, (01)
So a Sowa-class can change extension "at different times, places, and
possible (or actual) worlds." (02)
But some Sowa-classes do not change extension and some do - agreed? For
example the singleton set {John Sowa} does not change extension; but maybe
it is not a Sowa-class?
So we have some fixed extension Sowa-classes and some variable extension
Sowa-classes.
Sowa-classes that change extension can be indexed by the ways in which they
change extensions, fixing them modulo variables.
Sowa-classes that don't change extension don't need to be indexed. (03)
It sounds as if you are agreeing with me. (04)
Sowa-classes sound awfully like what a lot of people call concepts/terms.
They certainly aren't like sets.
I guess, if we want to have something that does not change extension, these
concepts/terms aren't up to the job. (05)
> In either case, there is no "instance" of a meter. The length of
something is
> always determined by a relation (some procedure that carries out some kind
> of comparison). (06)
Better to say, the length of something is always determined by a relation
(that *can* be evaluated some *possible* procedure that carries out some
kind
of comparison). Otherwise unmeasured metres are not a metre - an odd claim. (07)
> In either case, there is no "instance" of a meter (08)
Either way I can easily work out the instances. It is the actual (or if you
take on board the amendment above - the possible) evaluations. Unless there
is a Sowa-law that says it is bad manners to do so. (09)
For more see e.g. this excellent book
http://www.amazon.co.uk/Basic-Concepts-Measurement-Brian-Ellis/dp/0521095565
/ (010)
Best regards,
Chris (011)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F Sowa
> Sent: 17 July 2012 22:00
> To: ontolog-forum@xxxxxxxxxxxxxxxx
> Subject: Re: [ontolog-forum] The concepts can change?
>
> On 7/17/2012 3:35 PM, Chris Partridge wrote:
> > It looks to me as if one can distinguish between (a) terms/classes
> > whose definitions (membership conditions) change over time but whose
> > extension remains the same across time and (b) terms whose extensions
> > change over time, so are probably not classes in any set-theoretic
sense.
>
> For each class, the defining relation is fundamental. The set of
instances can
> change at different times, places, and possible (or actual) worlds.
>
> > for a standards body at any particular time there is an official
> > definition of a metre and so the extension of the class metre at any
> > particular time is fixed by the official definition at that time.
>
> The old standard was the distance between two marks on a bar made of a
> platinum-iridium alloy when measured at the melting point of ice.
>
> The current standard is equal to 1,650,763.73 wavelengths of the
orange-red
> emission line in the spectrum of a krypton-86 atom in a vacuum.
>
> In either case, there is no "instance" of a meter. The length of
something is
> always determined by a relation (some procedure that carries out some kind
> of comparison).
>
> Basic principle: the *relation* is fundamental.
>
> John
>
> _________________________________________________________________
> Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
> Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
> Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
> Shared Files: http://ontolog.cim3.net/file/ Community Wiki:
> http://ontolog.cim3.net/wiki/ To join: http://ontolog.cim3.net/cgi-
> bin/wiki.pl?WikiHomePage#nid1J
> (012)
_________________________________________________________________
Message Archives: http://ontolog.cim3.net/forum/ontolog-forum/
Config Subscr: http://ontolog.cim3.net/mailman/listinfo/ontolog-forum/
Unsubscribe: mailto:ontolog-forum-leave@xxxxxxxxxxxxxxxx
Shared Files: http://ontolog.cim3.net/file/
Community Wiki: http://ontolog.cim3.net/wiki/
To join: http://ontolog.cim3.net/cgi-bin/wiki.pl?WikiHomePage#nid1J (013)
|