When we try to define time, we define it based on an event which happens periodically. For example, in a clock,we say that the time elapsed is 1 minute if the second hand completes 1 revolution. Here we define time based on the periodic motion of the second hand. From Wikipedia, Motion is defined as:

Motion is a change in position of an object with respect to time

Here we are trying to define time based on motion which is in turn based on time. So the question is - does time exist in reality?

  • Can you specify your concern here? For instance, are you asking after contradictions/paradoxes of motion like Zeno's paradox? – Joseph Weissman Oct 22 '11 at 16:49
  • Even if it is a tough question, it deserves to stay on its own, without any more material. The reference to motion related definition is sufficient (and adequate). – Geoffroy CALA Oct 23 '11 at 16:16
  • @Geoffrey just having a reference to a definition does not strike me as "adequate and sufficient" given the lack of specificity and vagueness of the question. It is basically a topic for discussion rather than an answerable question as formulated. Please feel free to offer edits if you feel you clearly understand the questioners' motivation and context, but as it stands without context or a specific, focused and answerable question this is simply not constructive – Joseph Weissman Oct 23 '11 at 16:49
  • wikipedia, as much as it is a supposedly self correcting medium, is not necessarily a definitive account of anything.
  • your question could just as well be about motion or space (based on the given definitions) or even more so about how definitions of physical phenomena work. At some point, to make definitions usable, they refer to others definitions and those to others, but it is not so easy to deal with infinite regress ("turtles all the way down"). There needs to be an 'end' which is either explicitly terminal,that is, altogether undefined (or rests on intuition or inarticulate gesture) or is circular (as on your given example).
  • whether defined well or not, does a definition make time(or space or motion) exist? No, I think things 'exist' without needing to be defined by humans (for some intuitive notion of 'exist'). Time will elapse without our awareness of it. Or more relevantly, we can have a concept of time that works for others who may not be aware of the concept.
  • more generally, does a concept need to be well-defined to exist? I think that is really dependent on what you want 'exist' to mean. Suppose you consider a circular or an inconsistent set of definitions is taken to be nonexistence. That doesn't mean there's not a better workable definition.
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  • +1: your 3rd point is key, specifically where the OP might be entangling certain concepts – stoicfury Oct 22 '11 at 21:47

The question of time is an incredibly difficult one, which has been treated of philosophers from Aristotle to Heidegger. Thus, it's not something that can be solved in this forum.

However, we can say this: time does not exist in the manner in which, say, the book on my table exists. Time is not an entity.

Second: we can also say that time is necessarily relational; it requires at least two moments.

Third: we can also say that time is deeply entwined with change (or motion), and it doesn't make sense to speak of one without the other.

The IEP article on Time provides a good introduction; I suggest you take a look there, and then come back with a narrower question (perhaps based on a single philosopher.)

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