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Re: [ontolog-forum] Thing and Class

To: "'[ontolog-forum] '" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Matthew West <dr.matthew.west@xxxxxxxxx>
Date: Tue, 9 Sep 2008 08:45:45 +0100
Message-id: <48c629cd.2009360a.2304.309d@xxxxxxxxxxxxx>
Dear John,    (01)

> MU> The names I find most useful for these things are (substituting
>  > into the text above)
>  >
>  >  1. THING: the set of all things in the universe of discourse
>  >  2. CLASS: the set of all things that have member individuals
>  >  3. INDIVIDUAL: the set of all things that do NOT have member
>  >     individuals
>  >  4. ORDINARYCLASS: the set of all things whose members do not
>  >  themselves have members...
> 
> As we've discussed many times, the terms 'set' and 'class' are
> extensional, but the categories of an ontology are intensional.
> When Boeing designs a new *type* of aircraft, the *set* is empty
> until the first instance is built.  When any design changes are
> made, the result is a new type or subtype.    (02)

[MW] Under 4-dimensionalism, which looks at the universe from outside 
time and sees time as just another dimension, this is not the case. 
The set of Boeing 777s includes all those that are to be built as 
well as those that have been built.
> 
> But even for a fixed design, the set changes with every instance
> that rolls off the assembly line.    (03)

[MW] Only if you take a 3D perspective which sees what exists as 
What exists NOW.
> 
> You can't use extensional terms such as 'set' and 'class', which
> change with every instance that rolls off the assembly line.
> It's essential to use intensional terms, such as 'category' or
> 'type'.  Since 'type' takes one syllable instead of four, that
> is a good choice.    (04)

[MW] But you can if you are a 4-dimensionalist.    (05)

Regards    (06)

Matthew West
http://www.matthew-west.org.uk/     (07)


> 
> John
> 
> 
> 
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