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Re: [ontolog-forum] Thing and Class

To: "[ontolog-forum] " <ontolog-forum@xxxxxxxxxxxxxxxx>
Cc: "[ontolog-forum]" <ontolog-forum@xxxxxxxxxxxxxxxx>
From: Pat Hayes <phayes@xxxxxxx>
Date: Tue, 9 Sep 2008 16:57:58 -0500
Message-id: <p06240805c4eca054e16d@[]>
At 4:57 PM -0400 9/9/08, John F. Sowa wrote:

For many applications, I prefer a 4D ontology, but I also recognize
the need to map the categories of such ontologies to the language
that people use in everyday life.

PH> But the key point is that to assert existence in the 4d framework
 > an assertion itself is not temporal. Assertions stand outside time
 > and speak about it, rather than being embedded in it and having
 > to speak about other times indirectly, for example by using tenses.
 > Moreover, it frees one from the confusion that relates intensionality
 > to existence over time.

I agree, but Matthew claimed that the distinction between intension
and extension was not applicable to a 4-d framework.  To avoid the
temporal issues, I mentioned hypothetical statements, which might
not refer to anything in actual space-time in any coordinate system.

One can extend the 4-d to include hypotheticals in a straightforward way, as I'm sure you understand. In the terminology of my old 'liquids' paper, the basic universe comprises all possible histories: a 'possible world' is simply a maximal possible history under the obvious notion of parthood.

PH> There is no 'now' in a 4-d universe.

I used the word 'now' because Matthew used it.  But strictly speaking,
there is no here or now in a 3-d universe.

True, I spoke carelessly. The point is that there is no 'now' in an ontology which refers to entities as being embedded in space and time, rather than embedded only in space with an implicit assumption that the utterances refer contemporaneously with their use.

 The word 'here' and 'now'
are indexical terms that are always tied to a particular observer or
speaker.  In discussions of relativity in 4-d spaces, it is common
to talk about a different 'here' and 'now' for each observer.

Relativistic 4-d (Minkowski space) is a whole other ball of wax, not at all like the 4-d that Matthew and I are talking about.

But it seems clear that you and I agree on the essentials, so I won't go on and on about it :-)


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