E77 Existence

E77 Existence encompasses (and thereby isolates) entities which share two attributes: having the potential to exist over a period of time, and having persistent identity during this period of existence. These attributes are intended to apply to both concrete objects, whether animate or inanimate and to ideas or concepts. Hypothetical or imaginary objects fall within this category insofar as they can be considered as conceptual objects i.e. E77 Existence is not intended to be restricted to physical existence.

The conditions under which an object can be deemed to maintain its identity are often difficult to establish - the decision depends largely on the judgement of the observer. Most people would agree, for example, that a building ceases to exist if it is dismantled and the materials reused in a different configuration. Human beings, on the other hand, in common with many other organisms, go through radical and profound changes during their life-span, affecting both material composition and form, yet preserve their identity. Identity in these cases would seem to depend more on continuity rather than the presence of any particular physical state or component.

The main classes of objects which fall outside the scope E77 Existence are temporal objects such as periods, events and acts, and descriptive properties, (such as materials) which function as adjectives and adverbs. The former may have persistent identity but are excluded primarily to avoid the possibility of a meaningless regression of beginning and ending periods of periods, the later because they have no real identity, or, to be more precise, their identity is of no interest in the present context.

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Remarks:
The name *Existence" is confusing and may be need to be changed. It contravenes the general requirement of the ISA hierarchy that sub classes may be described by the form "X is a Y". "Stuff is an Existence", for example, stretches comprehension into the realms of speculative metaphysics. Placing the accent on persistent identity rather on existence may provide an acceptable alternative: "Persistent Item", for example, or possibly just "Thing". However, this would appear to create some overlap with the E70 Stuff (cf scope note). I would suggest renaming E70 Stuff to emphasise the notion of potential use, (which is the only attribute introduced by this entity) "Useable Thing", perhaps. Apart from being disarmingly colloquial the term 'stuff' is arguably inappropriate since the scope note clearly indicates that the entity is intended to encompass 'items' - the word "stuff" suggests (at least to me) undifferentiated material rather than persistent, identifiable and useable items.

NC 18 January 2002

Incidentally, my copy of version 3.2 contains the erroneous label "The entity is not referenced:" followed by the references!