RE: SUO: RE: RE: RE: RE: Collections - Aggregation or Set
>Ah, I see. So a collection *is* a mereosum, but with a special
>'part-of' relation which defines a set of 'privileged parts' , which
>are the (necessarily disjoint?) members of the collection. OK, that
>works, as long as one bears in mind the implications of the
>collection being a mereosum. For example, this means that the Wallace
>collection is also a collection of very small pieces of wood, canvas,
>dried linseed oil and pigment, though with a slightly different
>notion of privileged part; and it is also a collection of largely
>organic molecules, with a still different notion, and so on. All of
>which does indeed make sense, I agree. Still I can see no real
>utility to insisting that the collection *is* the mereosum, and this
>identification can be quite misleading. Why not have the collection,
>as one thing, and the mereosum of the members of the collection, as
>something else?
>
>CP> As I think I have said before. This choice eliminates the need to
>(possibly?) have a hierarchy of collections of collections - and a mixed
>hierarchy of sets of collections and collections of sets, where these seem
>to have no use, at least currently in the ways we are describing the world.
>It seems like unnecessary complication - something that surely does not
>appeal to an engineer?
Everything should be made as simple as possible, but not simpler. (Einstein)
<snip>
>I have one worry with the Guarino/West approach as you characterize it
>above.
>If a collection is identified with a mereosum (or indeed with a set,
>for that matter), then how does one account for the fact that the
>membership of a collection may change without altering the identity
>of the collection? For example, if a farmer sells some of his sheep,
>we say a single flock has become smaller, but both the set of members
>and the mereosum are different after the sale than they were before
>it. For collections like teams and orchestras and opera companies,
>the membership may change entirely without altering the identity of
>the collection, in notable contrast to both sets and mereosums.
>
>CP> I have written on this problem in my book (characterizing it as the
>'Logical Paradigm'). It is because the view is neither 3d or 4d, perhaps
>3.5D. You need to take the full 4-d extension of the flock.
(1) It isnt a 'problem' unless one insists on identifying collections
with mereosums or sets, which they aren't in general.
(2) I think the basic point applies independently of whether one is
using a 3-d or 4-d or any other spatiotemporal ontology. The fact
that a sheep may leave a flock without changing the identity of the
flock, implies that the flock itself is neither the set of sheep nor
the mereosum of sheep-stuff. The only way it can be a set or mereosum
in 4-d is if the things in the flock can be somehow incomplete sheep,
ie temporal parts of sheep; and the only way it can be a set or
mereosum in 3-d is temporarily, since the set/sum may change without
the flock changing.
Pat
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