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Re: [ontolog-forum] The concepts can change?

To: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: "Chris Partridge" <partridge.csj@xxxxxxxxx>
Date: Tue, 17 Jul 2012 22:25:44 +0100
Message-id: <008301cd6462$ba6dc0e0$2f4942a0$@gmail.com>
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
> 
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>     (012)


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