Persistence

• Perspective

- object (focus on spatial configuration) - process (focus on temporal evolution)

The concepts of endurant and perdurant implicitly rely on the concept of instantaneous 3D snapshot of the world object, that in the EMMO is not allowed since everything extends in 4D and there are no abstract objects. Moreover, time is a measured property in the EMMO and not an objective characteristic of an object, and cannot be used as temporal index to identify endurant position in time.

For this reason an individual in the EMMO can always be classified both endurant and perdurant, due to its nature of 4D entity (e.g. an individual may belong both to the class of runners and the class of running process), and the distinction is purely semantic. In fact, the object/process distinction is simply a matter of convenience in a 4D approach since a temporal extension is always the case, and stationarity depends upon observer time scale. For this reason, the same individual (4D object) may play the role of a process or of an object class depending on the object to which it relates.

Nevertheless, it is useful to introduce categorizations that characterize persistency through continuant and occurrent concepts, even if not ontologically but only cognitively defined. This is also due to the fact that our language distinguish between nouns and verbs to address things, forcing the separation between things that happens and things that persist.

This perspective provides classes conceptually similar to the concepts of endurant and perdurant (a.k.a. continuant and occurrent). We claim that this distinction is motivated by our cognitive bias, and we do not commit to the fact that both these kinds of entity “do really exist”. For this reason, a whole instance can be both process and object, according to different cognitive approaches (see Wonderweb D17).