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
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http://people.ifomis.uni-leipzig.de/pierre.grenon/
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