Re: SUO: Re: RE: Logic and Ontology
Chis,
In my previous note, I was not addressing 3d vs. 4d representations,
but the distinction between intensions (i.e., predicates or properties)
and extensions (i.e., the set of things that a predicate is true of).
I wanted to emphasize that if you have a single fixed universe of
discourse, the distinction between intensions and extensions can often
be ignored.
But if you are considering different universes of discourse, which could
be the state of the world at different times (if you are using a 3d
representation) or it could be the state of the world at different
hypothetical stages (which is just as relevant for a 4d representation
as it is for a 3d representation).
A 4d representation might be able to view the universe of discourse at
all points in time as a single set, but it still does not deal with
the question of different hypothetical worlds (as in the case of
different engineers discussing different design options for an airplane
whose design is still unspecified).
Bottom line: A 4d representation does not eliminate the need to
distinguish extensions and intensions. The "changes" may result from
shifts in the points of view or hypotheses instead of shifts in time.
John