Doug, (01)
DF> Don't you consider the distinction between physical objects and events/
> occurrences to be ontologically meaningful? (02)
As I am sure you know, the distinction has long been regarded as
problematic. The standard examples of problematic cases are avalanches and
waves - which seem to have the properties of both.
If one wanted to make it "ontologically meaningful" then a good description
would go a long way.
The syntactic difference between nouns and verbs is, of course, easier to
make - and might be the root for folk intuitions about objects and events. (03)
Regards,
Chris (04)
> -----Original Message-----
> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx [mailto:ontolog-forum-
> bounces@xxxxxxxxxxxxxxxx] On Behalf Of doug foxvog
> Sent: 04 February 2011 01:21
> To: [ontolog-forum]
> Subject: Re: [ontolog-forum] 3D+1 (was presentism...was blah blah blah)
>
> On Thu, February 3, 2011 4:37, Pat Hayes said:
> > Ian, here's a non-philosophical way to characterize it. Start with an
> > atomic sentence of the form R(a, b), with no time involved, and
> > suppose that a and b here are ordinary uncontroversial physical objects,
> say.
> > Intuitively, they are 3D things. Now add time, t. Where do we put the
> > time parameter? Several answers can be given.
>
> Pat, i like this description of 3D, 3D+1 and 4D.
>
> > 1. Attach it to the sentence, meaning that the sentence R(a,b) is true
> > at the time t. This gives you a hybrid or context logic where the
> > times are possible temporal worlds/indices or contexts, to which truth
> > is relativized. But the sentences being so relativized do not
> > themselves make any reference to time. Call this 3D.
> >
> > 2. Attach it to the relation as an extra argument, and call the
> > relation a
> > 'fluent': R(a, b, t) This gives you the classical AI/KR approach which
> > used to be called the situation calculus, where one quantifies over
> > times in the KR language itself, but the object terms are still
> > thought of as denoting 3D rather than 4D entities. Call this 3D+1.
> >
> > 3. Attach it to the object terms (using a suitable function, written
> > here as an infix @): R(a@t, b@t) This requires us to make sense of
> > this @ operation, and it seems natural to say that it means the
> > t-slice of the thing named, which now has to be re-thought as a 4D
> > entity. So the a, b things have morphed form being 3D (but lasting
> > through time) to being genuinely 4D, and having temporal slices or
parts.
> Call this 4D.
> >
> > For some folk this last step is apparently mind-boggling, although to
> > me it is puzzling how one can think of something being 3D and also
> > extended in time and have it *not* be 4D.
>
> One problem that people have with considering this 4D is that the 4th
> dimension is different. A physical object may be repositioned in any of
the
> three normal dimensions, but it can not be rotated in the fourth
dimension.
> Of course, nothing can happen to such a 4D object (unless a fifth
dimension
> is invoked), whereas an object with four spatial di- mensions could
> conceptually be rotated so that different parts of it intersect the
conventional
> three dimensional space.
>
> > For yet other people (think OBO), there are apparently two kinds of
> > thing in the world, one kind (continuants) which must be described
> > using the 3D+1 style , the other (occurrents) which should be
> > described using the 4D style. God alone knows why anyone would believe
> > that there are two ways to exist in time, but there's nowt as queer as
> > folk, as someone's grandmother used to say.
>
> Don't you consider the distinction between physical objects and events/
> occurrences to be ontologically meaningful? Why should it be curious for
> some people to think that elements of the two different categories exist
in
> different fashions?
>
> It is also useful to note that in a 4D model, aspatial temporal objects
> (accounts, laws, theories, ...) are one-dimensional objects.
>
> > What I like about this way of contrasting the options is that it makes
> > it be simply a matter of syntax - where in the sentence to attach the
> > temporal parameter - and not one of metaphysics.
>
> So do i.
>
> -- doug f
>
> > Syntax is way easier than
> > metaphysics. It also means that one can see quite clearly how to make
> > the various formal techniques work together, by allowing the temporal
> > parameter to 'float'. In fact, with a bit of extra work one can embed
> > almost all the necessary temporal reasoning into a generalized
> > unification algorithm which extracts temporal constraints during the
> > unification process. I have all the details somewhere if you (or
> > anyone else) are interested.
> >
> > Pat
> >
> >
> > On Jan 27, 2011, at 11:19 AM, Ian Bailey wrote:
> >
> >> Thanks John,
> >>
> >> So in a 3+1 approach, when they actually "cut some ontology code", if
> >> I've understood you correctly, I'm guessing they timestamp the
> >> properties and relationships ? This contrasts with a 4D approach
> >> where the Individual is sliced up into temporal stages and the
> >> properties are associated with the stages (apart from those
> >> properties that apply to the whole-life individual).
> >>
> >> If I've got that right, then 3+1 is the approach the oil and gas
> >> folks used in late 80s early 90s on EPISTLE and the first drafts of
> >> ISO10303-221.
> >> Am I
> >> in the right ball park there ? Matthew ?
> >>
> >> Cheers
> >> --
> >> Ian
> >>
> >> -----Original Message-----
> >> From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
> >> [mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of John F.
> >> Sowa
> >> Sent: 27 January 2011 17:05
> >> To: ontolog-forum@xxxxxxxxxxxxxxxx
> >> Subject: Re: [ontolog-forum] 3D+1 (was presentism...was blah blah
> >> blah)
> >>
> >> On 1/27/2011 11:17 AM, Ian Bailey wrote:
> >>> I get 4D, finally, after years of hanging on Chris and Matthew's
> >>> coattails, but the 3D+1 thing is a mystery.
> >>
> >> The basic issue is the definition of a physical object and its
> >> relationship to a privileged time called 'now':
> >>
> >> 1. In 3+1 D, which is the implicit assumption in ordinary
> >> language, an object (human, animal, plant, or artifact)
> >> comes into existence at some time t1 (e.g., birth),
> >> ceases to exist at some time t2 (e.g., death), and
> >> for each now between t1 and t2, all parts of it
> >> exist together now.
> >>
> >> 2. In 4D, a physical object extends over a 4D volume, whose
> >> lower and upper time coordinates are t1 and t2 and whose
> >> spatial coordinates trace out a volume that spans the
> >> object's travels.
> >>
> >> 3, In 3+1 D, the object undergoes various changes, which
> >> cause some properties to become true or false at different
> >> times called now.
> >>
> >> 4. In 4D, the object doesn't change, but it has time-dependent
> >> parts (slices or stages) at which various properties may be
> >> true or false.
> >>
> >> The analogy I prefer (since I studied fluid mechanics at one time in
> >> my life) is between Lagrangian and Eulerian coordinate systems for
> >> representing and computing fluid flow:
> >>
> >> 1. Lagrangian coordinates are like a 3+1 D system: the
> >> observer follows a particular parcel of fluid as it moves.
> >>
> >> 2. Eulerian coordinates are like a 4D system: the observer
> >> sits on the side and watches the flow of all the fluid
> >> as a whole.
> >>
> >> In our ordinary language, we talk about our bodies in Lagrangian
> >> terms. We observe our own motion through space and time, and relate
> >> everything else to where we are *now*.
> >>
> >> An Eulerian system is like a God's eye view of the universe.
> >> God sees everything spread out in all dimensions of space and time.
> >> There is no privileged point of time or space.
> >>
> >> John
> >>
> >>
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> =============================================================
> doug foxvog doug@xxxxxxxxxx http://ProgressiveAustin.org
>
> "I speak as an American to the leaders of my own nation. The great
initiative
> in this war is ours. The initiative to stop it must be ours."
> - Dr. Martin Luther King Jr.
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