Re: [ontolog-forum] Thing and Class

[Pat Hayes <phayes@xxxxxxx>]

At 4:57 PM -0400 9/9/08, John F. Sowa wrote:

> Pat,
>
> 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 :-)

Pat

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