RE: RE: SUO: Re: Ballot Comment
>Dear Adam,
>
>See responses below.
>
>
>Matthew West
>Principal Consultant
>Shell Information Technology International Limited
>Shell Centre, London SE1 7NA, United Kingdom
>
>Tel: +44 20 7934 4490 Other Tel: +44 7796 336538
>Email: matthew.r.west@is.shell.com
>Internet: http://www.shell.com
>snip of headers.
> > > >
> > > > Matthew,
> > > >
> > > > At 10:09 AM 8/29/2001 +0200, West, Matthew R SITI-GREA-UK wrote:
> > > > >Dear Adam,
> > > > >
> > > > >If you don't mind changing the meaning of the concepts involved
> > > > >so that they are 4D rather than 3D concepts, then your
> > axioms would
> > > > >probably work.
> > > >
> > > > Could you explain further what you mean by "don't mind
> > changing the
> > > > meaning..."? The only meaning the terms have is from
> > their axioms.
> > >
> > >MW: I admit I am reading the words rather than the axioms, and it is
> > >possible that the SUMO has not added those axioms that would make it
> > >specifically 3D. The only point is that you can't be both at the
> > >same time, you have to be one or the other, or have each in different
> > >places (what I am proposing).
> >
> > Well, it sounds like we just disagree on whether this is
> > possible. I'm
> > looking for an operational, computational definition of what
> > it would mean
> > that they "can't be both at the same time". The only operational
> > definition I can think of would be the one could prove a
> > contradiction
> > using first order logical inference. Since that's not the
> > case I have to
> > conclude that it is possible unless someone offers another
> > operational
> > definition. But forgive me, I've said as much before, and I
> > know my saying
> > it again doesn't move us along. I wish I knew what would and
> > I appreciate
> > that you're still trying.
>
>MW: There are two issues here.
>
>1. I have not had the time to go through the relevant parts of
>SUMO to see whether there are inconsistencies with 4D, so I cannot
>say with certainty whether there are or not, and if so what they
>are. I estimate it would take me a manday or two to do this.
>
>2. There are basically 3 possibilities for the SUMO.
>
>a) It is a 3D ontology with appropriate constraints that specify
>objects as continuants.
>
>b) It is a 4D ontology with appropriate constraints that specify
>both static and dynamic objects as spatio-temporal extents.
>
>c) It is vaguer than either of these and has no constraints that
>would distinguish 3D from 4D objects.
>
>The third of these is the worst possible case of course, since
>someone's intent of being a 3D object or a 4D object could not
>be discerned or acted upon.
>
>One important difference between 3D and 4D objects is that in
>a 4D world an object is uniquely defined by its spatio-temporal
>extent and nothing else. This is not so for a 3D object. For
>example the clay (substance) a vase is made out of is always
>considered a separate object from the vase itself.
I think this distinction is strictly orthogonal to the 3d/4d one. One
could have a 3-d view which identified a vase with its constituent
clay (as in some mereologies) and conversely one could also imagine a
kind of intensional 4-d view which allowed a number of distinct
entities with the same spatiotemporal envelope (eg one which
distinguished the vase-considered-as-stuff from the
vase-considered-as-manufactured from the
vase-considered-as-fragile-object). It is however true that it is
more 'natural' to adopt strict extensionality in 4-d than in 3-d
since many of the examples which motivate nonextensionality in a 3-d
view involve change, and these examples are much less convincing in
4-d.
Pat Hayes
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