


Overview
General Formal Ontology (GFO)

6.1 Endurants, Presentials, and Persistants
In our approach, we make a more precise distinction
between presentials and processes, because
the philosophical notion of endurant combines two
contradictory aspects.
Persistence is accounted for by two distinct
categories: presentials and persistants. A
presential exists wholly at a
timeboundary. We introduce the relation
with the
meaning the presential x exists at
timeboundary y.
We pursue an approach which
accounts for persistence using a suitable
universal whose instances are presentials. Such universals are called
persistants. These do not change, and they can be used to
explain how presentials that have different properties at different
times can, nevertheless, be the same.
Endurants exhibit two aspects that contradict each
other.
If, for example, an endurant is wholly present at two
different timepoints and , then there are two different entities
`` at '' and `` at '', denoted by and , respectively. Now
let us assume that persists from to . For example,
newborn Caesar exists at time , ,
while Caesar at age of 50 at , ; both entities
and are wholly present at these timepoints, and they are
obviously different. What would it mean to say that both are
identical? Our solution to this problem is to separate
endurants into wholly present presentials and persisting
persistants. That means, and are not identical, but they are
equivalent, because both are instances of the persistant.
If we assume that only those things exist that
exist at present (presence understood as a timepoint without any
extension), then presentials should be wholly present at the present
timepoint. Persistants are not arbitrary universals. They satisfy a
number of conditions, among them the following: (a) every instance of
a persistant is a presential; (b) for every
timeboundary there is at most one instance which exists at this
timeboundary; and (c) there is a chronoid such that for every
timeboundary of the persistant has an instance at this
timeboundary. Further conditions should concern the relation of
ontical connectedness and the relation of persistants to processes.
Robert Hoehndorf
20061018

