RE: SUO: RE: RE: Basics of Process and Event, 3D and 4D
Pierre,
You are quite right to point up the finer details of the metaphysical
choices and it correct to keep reminding ourselves of them. I do not want to
discourage you, but, if I may, can I add some more detail.
You wrote "There is a difference between having the same spatiotemporal
extent and having
the same (spatio)temporal parts. ... ..."
I agree in principle, but hope you accept that 4D's attractiveness is that
it enables an extensionalism which a 3D approach cannot - and so they go
hand in hand. I recall this point being made in a number of places - e.g.
Loux in 'Metaphysics'.
You also raise the question of being substantivalist about spacetime - and
say "It seems odd to me to require (3) as a principle for 4-D. I see that
this [3)] could be endorsed by some 4d theories and rejected by others.
Inter alia, it depends on how you regard spacetime itself."
I accept that you wrote 'require' - but this seems me maybe a little
disingenuous. It seems to me to be in the parsimonious spirit of 4D-ism to
NOT be substantivalist about spacetime. For someone who finds extensionalism
attractive, allowing two categories and so co-location across them is the
thin edge of a wedge that opens the door to even more (co-locating)
categories (am I mixing metaphors?). I know there is a tradition in
philosophy which analyses the conceptual dependence between the positions -
and agree this (and your point) is important. But it is also useful to
understand the motivation and how this links positions.
Also, some people (not you, of course) seem to be a little equivocal about
their spacetime substantivalism. Philosophers of physics (such as Nerlich)
raise questions about a physicist's spacetime that seems (to me at least) to
be very different from things such as 'the space between the two columns' or
even 'the equator' or 'countries' (sometimes offered as examples of
non-material-spacetime entities) - and so these require different arguments.
Regards,
Chris
-----Original Message-----
From: owner-standard-upper-ontology@majordomo.ieee.org
[mailto:owner-standard-upper-ontology@majordomo.ieee.org]On Behalf Of
Pierre Grenon
Sent: 20 June 2003 14:22
To: West, Matthew R SITI-ITPSIE
Cc: Standard-Upper-Ontology (E-mail); Fowler, Julian
Subject: Re: SUO: RE: RE: Basics of Process and Event, 3D and 4D
Dear Matthew,
I had to abstain from wandering on SUO lately (but for Jon's tutorials which
I
always make a point to followreligiously), I'm pleased to see that there's
good
stuff going on now.
Comments on your (3) below.
Best
Pierre
> > >
> > 4 dimensionalism as I learnt if from Chris Partridge, as I
> > had confirmed by Pat Hayes and as stated in Ted Sider is
> > founded on the following propositions.
> >
> > 1. Existence is a manifold of 4 dimensions, 3 space and time.
> > I.e. when I refer to things in the past they exist, and
> > when talking about the world I stand outside time.
> >
> > 2. Individuals extend in time as well as space and have
> > temporal parts as well as spatial parts.
> >
> > 3. When 2 individuals have the same spatio-temporal extent
> > they are the same thing.
There is a difference between having the same spatiotemporal extent and
having
the same (spatio)temporal parts. The former is about location in spacetime,
the
latter about mereology. (Unless I missed a terminological consensus about
extent in your discussion.) In a substantivalist treatment of spacetime,
having
the same spatiotemporal extent is called colocation or coincidence. If you
treat extents as parts of some kind of the entities existing in spacetime,
then
having the same spatiotemporal extent means overlap. (Even in this latter
case,
it is not obvious that the entities only have parts which are extents of
this
sort, so even here colocation doesn't collapse trivially to equality.)
It seems odd to me to require (3) as a principle for 4-D . I see that this
could be endorsed by some 4d theories and rejected by others. Inter alia, it
depends on how you regard spacetime itself.
> > JPF> I know what the intent here, but it doesn't come across
> > in this wording. How about "when individuals are identified
> > or described as being distinct but have the same
> > spatio-temporal extent, they are the same individual".
IMHU, this means the same thing as the previous statement or there is
somethimng fishy about 'identification' and 'description'.
> > Otherwise there is a mapping problem for individual <-> thing.
>
> MW: I think the "formal" definition goes something like:
>
> For some x and some y, for all z iff z is a part of x and z is
> a part of y then x=y.
>
> i.e. they are the same if they share all their parts.
There is an axiom of mereology which claims that (it's usually laid down
with
prper part). So you seem to take spatiotemporal extents as parts of
entities?
Again, see above, even if this is the case, why sharing extents means
sharing
all parts?
The principle 3 is:
For all x for all y (if x and y are spatiotemporally colocated then x = y)
(Again I think this is rather strong for a general version of 4D. The
converse
is trivial however.)
> > It is still possible to go in different directions from there,
> > but that foundation of what individuals are is shared.
Don't think so. 3 is optional.
[...]
> > thing. Item 3 is the one most at risk.
Indeed.
--
Pierre Grenon
IFOMIS Uni Leipzig
Haertelstr. 16-18
04107 Leipzig
http://people.ifomis.uni-leipzig.de/pierre.grenon/
pgrenon@ifomis.uni-leipzig.de
phone: 49(0)351971672
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