All the things we perceive undergo changes as time goes by. Even if we didn't do anything, Time does 'its' work. For communication we use this word as an idea. If 'Time' were just an idea it couldn't have made any changes by itself. If so, is 'Time' just an idea?

Motion & Time may be interrelated. I wish to get a logical answer to this question (that does not include particles & waves).

  • According to Kant, it isn't a (mere) idea, but our form of (inner) perception/intuition and a necessary presupposition to think the perception of objects as objects at all.
    – Philip Klöcking
    May 31, 2016 at 15:25

5 Answers 5


Because time can be measured by clocks, time is a property of our environment and exists independently from the human mind. It is neither a mere idea nor solely a form of human intuition.

That answer from the viewpoint of physics contradicts the characterization due to the philosophical viewpoint of Kant, as correctly stated by Philip.

One of the deepest insights into the nature of time is due to the Special Theory of Relativity: Time has always to be considered in connection with space as part of a four-dimensional physical object called spacetime. There is a certain arbitrariness how we decompose spacetime into space, measured by yardsticks, and time, measured by clocks. As a consequence, events which happen simultaneously for one observer, may happen at different times for a second observer.

To understand these features of time requires some familiarity with physics - but I think you did not ask for an explanation which goes too far into this subject :-)

  • Just some nitpicking: It is questionable wether Kant did not in fact describe an undestinguishable space-time of experience for all objects of spacetime, where space and time are mere abstractions. Then, Special Theory of Relativity would only make scientifically explicit what Kant philosophically showed as necessary for experience of (outer) objects as such. He had a theory of necessarily relative space(s) as well, but I am not aware of such reflections on time/spacetime.
    – Philip Klöcking
    May 31, 2016 at 18:21
  • 1
    @Philip Klöcking I read your comment as considering whether Kant's conception of space and time is compatible with, or possibly even anticipating the spacetime concept of Special Relativity. In that case the decisive test would be: Did Kant mention somewhere that simultaneity of events can depend on the oberserver? I read from your comment that you do not know any passage where Kant discusses such questions. Because you know Kant very well, this suggests that there are no such passages in his work.
    – Jo Wehler
    May 31, 2016 at 18:50
  • To be more specific, "events which appear to happen simultaneously for one observer, may appear to happen at different times for a second observer." Since Minkowski space is time-orientable, given known topology, adjusted clocks can be truly synchronised, as with those on GPS satellites, so we can actually keep track of absolute simultaneity, Feb 14 at 11:12

This question is the subject of a vast amount of philosophical inquiry which includes idealist views, realist views, and everything in between.

Since Kant has been mentioned by other users, and your question is about the idealist view, I thought I’d tempt fate by attempting to summarize Kant’s “idealist” position - if nothing else, it will be helpful to me.

For Kant, space and time are not “things in themselves”; they are “forms of experience”. This is to distinguish between what we experience and the nature of experience - i.e., what we find in our experience and the nature of our experience. Another way of saying this is that we do not experience things in time and space, rather we experience things spatially and temporally. Note the noun/adverb distinction.

At this point, it is probably safer for me to continue by directly quoting a professional philosopher, Adrian Bardon :

Just like Parmenides and Augustine, Kant concludes that reality itself is atemporal. Is such a thing (i.e., the atemporality reality) even thinkable? Yes and no, Kant would say. His theory explains imagination’s inevitable failure in this regard: Because this way of experiencing things is an irreducible part of our sensibility, we literally cannot imagine any other way for things to be. Yet we can intellectually come to terms with the ideality of time. In this way the ideality of time is like the mathematical concept of infinity : We cannot imagine the infinite (we cannot call up a mental image of, say, an infinite number of apples), but we can understand what it means. Kant thinks that an atemporal reality is something we can grasp in the abstract, even if it can never mean anything to us in practical terms.

As Bardon notes, Kant has been roundly criticized for this view.

Bardon summarises Kant’s position as follows :

Just as space and time are forms of sensibility, the concepts of substance and cause are just rules for organizing experiences in time and space. The idea of temporal succession is innately present in our cognitive make-up, via a set of organizing principles. Thinking in terms of temporal succession of experiences depends on relating those experiences to successions of events outside us; and we can only do that because we already have a certain schema built in for interpreting our sensory inputs in these terms. Part of our innate information-processing scheme is that we interpret our perceptions on the presumption that we are dealing with a world of enduring items and events, interconnected by causal relations.... We are guided by this scheme into imposing a pattern on experience consistent with such a world; this scheme involves sequences of events occurring in accordance with causal rules. So this is how we come to have the idea of succession: It is a pattern corresponding to the concept of objectivity itself that we ourselves impose on sense data to make them tell a coherent story.


"Time is that which clocks measure" -Einstein

The moving hand of a clock does not "prove" the existence of time any more than the markings of a ruler "prove" the existence of space. A ruler allows regular, repeatable comparisons of length, nothing more. The moving hand of a clock is just a regular, repeatable motion that allows people to synchronize their movements and activities. Additionally, because the first clocks were based on pendulums, and the definition of a second is based upon the wavelengths of radiation emitted by a Cesium atom, we see that our notion of "time" comes back to and reduces to distance.

"The distinction between the past, present and future is only a stubbornly persistent illusion" - Einstein

Neither the past nor the future actually exist [in any physical sense]. The past is what we call a collection of memories. The future is speculation upon what memories might be added to the existing pile. Both are mental constructs, and have no physical characteristics.

Time is simply the way we manage our pile of memories, and arrange them into a logical procession, a filing system and nothing more.

[Einstein demonstrated] that space IS time, and time IS space. It is equally correct to say that something is X miles long as it is to say it is Y seconds long. Time is an indication of movement. Time is how we make sense of movement. Movement produces the sensation/experience of time, not the other way around. Indeed, if a giant button was pressed that stopped all movement in the universe, would we not think that time had stopped as well? How could we confirm time's "flow" or even its very existence with a universe in which no movement occurred? Without motion, the ability to compare two different physical states, time loses all meaning.

That thin demarcation between the ideas of past and future is the present, and is the only thing that truly exists.

(The above lifted from a previous answer of mine)


Time is not 'just an idea,' nor does it have substance, therefore can not cause anything. We can observe that time is neither cause nor effect. Time is without intrinsic feature, except for the events and conditions it contains. There can be no time without events. Time is the duration between events.

  • A no event is also event; if you have 5 mints break between two events its also has the same importance of an event in the context. I think time is deeply embedded with space. Eg i was at US; but if i say i was in US at 2010 jan 1 it make more sense and we have much clear statement than the previous one.
    – Eldho
    Dec 2, 2017 at 17:27

Change, really, is what we are talking about. What we call time is a rate of measure for a particular change.

So then change becomes the question at heart.

Does anything actually change or is change itself just a ping pong of atoms colliding off one another, and also bonding together.

To quantify change or capture its essence seems an absurd notion, yet people everywhere are constantly adjusting and molding out their life as if it where possible.

I believe Leibniz and Nicola Tesla both agreed time was a temporal illusion, though important in its own right.

  • 1
    I think that time/change/reality is seen as an illusion comes from a misunderstanding from what these philosophers are saying. It's a temporal illusion from the vantage point of eternity. As mortals, we do not have the privilege of this vantage point. So for us, time/change/reality is real. Feb 14 at 23:28
  • Interesting. I enjoyed reading your profile @MoziburUllah as too write a lot poetry. Anywho, yeah.. time being an illusion is okay if the right mind-set can take it as still important. Sort of what I meant I think in in my above comment. "Important in its own right". Have a good day Sir!
    – Kris
    Feb 16 at 6:21

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