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
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. But also material objects in daily use also undergo
material changes due to maintenance etc. without changing 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
Rename E77 Existence into E77 Persistent Item.