realistcat wrote:
i still don't understand what you're trying to say. If it's a question of what "really exists", then it seems to me a criterion of this is anything that does anything or is needed to explain something or anything that actually occurs or has any causal powers.

We don't perceive an instant, which is infinitesimally small, but we do perceive things as occurring "now." We can take "now", at time of use, to designate a finite duration. In particular, to designate the time when we say or think "now". Thus the "interpretation" for "now", as an indexical, requires its referent to be determined by the time of use of the word.

Of course it is a true that a thing may be changing during that finite time designated by "now." In practice "A is F" is taken to be true if A has property F at some time during that duration or througout that duration, depending on how reference to time is interpreted in that case. In a number of non-Indo-European languages (such as Chinese) verbs do not pack in a reference to time. You need a separate temporal adverb for this purpose.

Thus if it's a question of something's location "now", and that thing is moving, we could interpret the reference to location as incorporating the entire area occupied by it throughout that time. So if it's moving from P1 to P2 during the finite time designated by "now", we can take that P1-to-P2 trajectory as the location designated by "there" in "It's there now".

realistcat wrote:

then it seems to me a criterion of this is anything that does anything or is needed to explain something or anything that actually occurs or has any causal powers.