According to Kant, time is a pure intuition, meaning (in part) that its existence depends on the nature of human cognition. According to this doctrine, Other beings could in principle not experience time though they live in our universe. There are other accounts of time as well which attack the idea of time as an independent physical reality and make it something else. I find that I am unable even to grasp what it would mean for these sorts of things to be true.

It's not the same with space. Space is another pure intuition according to Kant, and in the case of space, I believe I can at least grasp the concept that space is just how humans intuit the relationships between objects. Other sorts of beings might have very different intuitions of space. Imagine, for example, a blind creature who lives in water and can't swim but can only crawl along the bottom. Such a being might detect objects through sound. What we see as distance, this being hears as volume. Horizontal angle might correspond to what we hear as differences in tone such as the difference in tone between a guitar and a saxophone playing the same notes. Distance above the surface might be represented by pitch. This being could understand position and motion as a theater of sound, having no sense of space as we understand it.

However, the creature would have to have a sense of time similar to ours. It has to recognize that events happen in order, and that there is no going back to a previous event. And the creature would have to have a sense that there are future events that must be prepared for (such as the approach of a predator). How else could it interact with the world? Or, taking seriously the notion that time is a pure intuition, how else could the creature interact with the temporal universe that humans experience in a way that is rational and leads to survival?

The notion of a sequence of events that plods on incessantly, with no possibility of going back or stopping or hurrying forward, and with the need to react to what is coming in the future, based on what is learned from what happened in the past--that's what time is. How could any creature exist in our universe without sensing that in roughly the same way we do?

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    Galileo rolls a ball down an incline plane and he tracks time by the periodic motion of a pendulum. During any instant of time there is only a space relation and time is only the perception of changes of the position of objects in space. Does reality keep time or have a time attribute inherent in the dynamic pendulum or processes that we call an atomic clock? We internalize the memories of events that are timeless in each instant of time and these memories or feedback loops in physical systems generate our sense of time. On the other hand some physical systems have a parameter: time constant. Aug 10, 2023 at 18:29
  • Time is what a clock measures therefore time is not real iff identical clocks cannot be synchronized or related by a transformation rule.
    – g s
    Aug 10, 2023 at 19:56
  • Kant had a very abstract conception of "intuition" and space as a form of it, I do not think your creature's intuitions of space are relevantly different from ours in his sense (he knew blind people can do geometry). What you describe as the creature sharing with us on time is similarly structural. "Creatures like us" are just those with "discursive" intellect, split into sensibility and understanding. In CJ he does describe unsplit "intuitive" intellect (hinting at God) that grasps temporal chains as wholes, no passage of time. We cannot grasp it because our intellect is not set up for that.
    – Conifold
    Aug 11, 2023 at 0:52
  • @Conifold, so Kant's notion of pure intuition is something that would be shared by any possible creature who was limited by space and time? That may be the answer to a dispute we had perhaps a year back when you labeled a position I was trying to explain as a form of psychologism when I was saying it was no different in principle from Kant's pure intuition. Aug 11, 2023 at 4:05
  • I explained my understanding in What is "intuition" for Kant?, but I do not remember what the dispute then was. I would rather say that creatures with Kantian sensibility frame their appearances in something structured like our space/time. "Temporal universe", "limited by" suggest they are real, but Buddhists, Kant and relativity eternalists contend reality is not what appears in time. It is maya/appearance/illusion on a timeless substrate. Our affinity to the creatures is here due to vaguely similar cognitive faculties, not shared reality.
    – Conifold
    Aug 11, 2023 at 4:33

4 Answers 4


'Time is not real' should be understood not as the claim that you do not experience time, but rather time is constructed by our brains and is not strictly speaking physical.

From the SEP article Time:

In a famous paper published in 1908, J.M.E. McTaggart argued that there is in fact no such thing as time, and that the appearance of a temporal order to the world is a mere appearance. Other philosophers before and since (including, especially, F.H. Bradley) have argued for the same conclusion.

Going back to the Hobbesian notion that change is motion (PhilSE), and as the user SystemTheory has noted, time is a shorthand for motion. A year is the motion of the earth about the sun. A day is the shorthand for the motion of the earth spinning relative to the sun. An hour is 24th of a day, and so on. Consider what seems so revolutionary when you first learn it, that time is relative to a frame of reference, really isn't. Time dilation is non-Netwonian because of the metaphysics that says the speed of light impacts our experience of clocks. You cannot smell time. You cannot feel time. You cannot weigh time or put it in a container. You can simply experience it by noting change. 'Time' in the abstract, simply is experience generalized over concrete experiences of definitive periods of time. The next best definition are the circular definitions of time, velocity, and motion, each defined in terms of the other.

Dennett is his book Consciousness Explained has a chapter devoted to the psychology of time which is much more contemporaneous and scientific than Kantian language. On page 144, in the chapter Time and Experience, Section 2. How the Brain Represents Time, he goes out to map how the brain functions in architectural terms and makes a simple argument. Time is a type of non-sensory neural calculation that is used to help sequence bodily events. As such, the building blocks of consciousness, events, are nothing more than a collection of events which are themselves delimited by two unique events: one of which marks the beginning and one which marks the end creatively delimiting events recursively temporal content.

Time as a construct of the mind is a concept supported by the framework of embodied cognition (SEP). The basic premise of embodied cognition is that the products of the mind, that is mentality and to a wider degree philosophical intentionality are directly grounded in, shaped, and constrained by the nature of the body that produces the mind. (Yes, there's a metaphysical presumption about the relationship between mind and brain.) In fact, it is a central contention of embodied cognition that mind is understood much more broadly than mere brain activity, but includes the body itself supported by such hypotheses as the somatic marker hypothesis and provides a foundation that cognition itself might be understood as extended or social in nature.

Given that we are born with naive realism as our fundamental cognitive strategy for organizing our mental activities, it is important to reflect on 'real' as understood through the lens of broader meta-ontological commitments. If your notion of 'real' is tied up in empirical claims, then it might sound nonsensical to declare time imaginary if imaginary is used as a synonym for bogus, illusory, or not accessible to the public. You invoke the term reality, but to a conceptualist like McDowell, it is important to differentiate among physical, perceptual, conceptual, and social forms of reality.

Classic physics notions like time, space, and energy aren't sensible. They are instead intuitive faculties that allow our consciousness to emerge and persist. They are not directly available to our senses, but rather allow our senses to come into being. This is what makes Kant's project of marrying Newton to Leibniz so fruitful. The recognition that time like space are intuitions that inhere to the mind helps us to understand the role intuition plays in framing our conscious experience and reframing the conversation in a layered model of reality leading from the noumenological with its pervading ontological ambiguity through the mysteries of qualia right to understanding the role language plays in shaping our concepts.

What about 'real time'? Doesn't time have to exist external to our thoughts? Well, that's not so clear. When talking about any form of reality, we are dealing with our thoughts about what reality is. If I make the claim 'time is real', reality itself is our model of the external world, and that model or any model of the universe is itself inescapably grounded in thought. This may be why the Wikipedia article on time says:

Defining time in a manner applicable to all fields without circularity has consistently eluded scholars.

Is human-like intelligence predicated upon this basic architectural feature of the embodied mind to create temporal content to augment mental representations for the purpose of sequencing and coordinating among the disparate parts of the body and keeping the sensory percepts organized? I would speculate yes. In much the same way that computer architecture has to have common features to embody physical computation, so too I suspect does language use and logical consequence depend fully on the same sorts of bodies that we broadly call animals.

For more information, see:

Time (SEP)
The Experience and Perception of Time (SEP)

  • i sort of get it when you say "it is not physical", but without real time in what sense is what we experience changing? doesn't the existence of a changing illusion imply real change? how can time be illusion all the way down?
    – user67155
    Aug 10, 2023 at 20:45
  • sometimes i get the idea, other times i do not. ok the time isn't/nothing is changing. but then how is it that there are changes to how things appear?
    – user67155
    Aug 10, 2023 at 20:52
  • "time is a shorthand for motion. A year is the motion of the earth about the sun" It seems to me that you are equivocating between time and periods of time. A year is a period of time, it is not time itself. This is like saying that space doesn't exist because a meter is just a multiple of a certain wavelength of light. This makes no sense because the argument that space does not exist presumes that space exists, and similarly the argument that time doesn't exist presumes the existence of time. Aug 10, 2023 at 20:56
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    @user66697 I have been meditating on the notion that time only makes sense if you intuitively accept time exists before proving it. I have for many years. I have just accepted it's an infinite regress. Maybe that's the wrong way to go?
    – J D
    Aug 11, 2023 at 4:38
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    @JD, my objection isn't against non-well-founded definitions (as an anti-reductionist, I embrace the non-existence of well founded definitions). My objection is that when the issue is the unreality of time, any account of time trying to show that time does not exist cannot presume that time exists. The contradiction is in trying to demonstrate non-existence by assuming existence. Aug 11, 2023 at 15:35

Ok so you need two things. How we think about the function of dimensions. And our sensorium gets composed into experiences of the world, outside of our conscious awareness.

In this answer I relate our mathematical intuitions, to shared experiences of continuous symmetries: The Unreasonable Ineffectiveness of Mathematics in most sciences Consider time-crystals as an analogue to patterns in spatial arrangement, that generate properties. You can also look at Does light experience time? to understand how experiencing time is not necessary to have impacts on the world, but, it is required in order to travel below the speed of light, and have a rest mass.

This answer covers how the forward direction of time can be understood as the spreading out of information: How does entropy explain consciousness and the forward direction of time? Almost all fundamental physics is time-reversible, except a few CPT invariant processes involving the weak force, like beta decay, and these are thought to created the matter-antimatter assymetry in the universe. So know the ordinary processes of our biology could literally run backwards. What would that feel like? Information (quantum correlations) would get more concentrated - and that would relate taking away memory, instead of adding it. So maybe we can go backwards in time, we just can't remember it, and our subjective experience stitches together experiences in time order, only because our memory requires it.

Loop Quantum Gravity has a picture of emergent time, from a spin-lattice network. Carlo Rovelli describes events as like they are surrounded by a crowd of probabilities, and the timeline picks from them to move onward. The probabilities existence have real physical consequences, like the Higgs Mechanism, and Renormalisation Groups.

Time can be related in terms of Noether's Theorem, to the continuous symmetry of conservation of information, the conjectured but not proven law, used in solving the blackhole information paradox and indicating the holographic principle.

Anil Seth is a particularly clear expounder of how our brains do substantial work on our sensory inputs, to structure the information we have coming in so as to be suited towards us acting, like in this TED talk: How Your Brain Hallucinates Your Conscious Reality. We catch sight of this when we see how blind people use the same visual cortex, to include a lot more stored and non-geometric information from all their other senses. We can also look at how how our brain hemisphere assymetries (see hemispherectomy), seem to be related to having two models of the world, one with a slight bias inwards, one outwards, sustaining a sense of an external world which we are a mind-body within - even though for physics there are just, events.

It's easy to think of causality as fundamental, as a clear intuition. The real-patterns of particle physics mislead us, that all causal units are so self-evident. When we really think about it, causality even of particles, is really only a kind of story-telling. Discussed here: Is the idea of a causal chain physical (or even scientific)?

Imagine a being, with parts inside itself moving sufficiently quickly, that they would experience time dilation relative to each other. How would that being experience time? It would be a bundle of timelines with rythmic variations (what moves away would have to move back, if it's not fragmenting), not your intuition of one clear one.

Or consider by analogy with us observing a being in Flatland, how a being in higher dimensions than us would observe our own. Discussed here: Is it possible to visualize higher dimensional space? Even bound by time, they would have a radically different experience of events, seeing our timeline as just one surface in a volume containing all the branched possibilities.

  • "[time] is required in order to travel below the speed of light" presumes the existence of time. Time reversible mechanical theories don't say anything about time, only about the symmetry of the equations. Aug 10, 2023 at 21:05
  • @DavidGudeman: A cosmos with only photons has no time, see Penrose's Conformal Cyclic Cosmology. Time reversal is permitted by the physics, so I asked you to engage in a thought expetiment: What would reversing the time direction on your body feel like? I argue, you could not experience the reversal, it would feel like time going forwards.
    – CriglCragl
    Aug 10, 2023 at 21:46
  • If the photons are moving with respect to each other then there is time. Any motion or change presupposes time. Aug 10, 2023 at 23:57
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    Time is nature's way of keeping everything from happening at once --John Archibald Wheeler Aug 11, 2023 at 2:34
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    @DavidGudeman: Not for a photon, because "the photon itself experiences none of what we know as time: it simply is emitted and then instantaneously is absorbed, experiencing the entirety of its travels through space in literally no time" forbes.com/sites/startswithabang/2016/09/30/… Or see discussion here: physics.stackexchange.com/questions/29082/…
    – CriglCragl
    Aug 11, 2023 at 8:40

The relationship of time to space has been known since the appearance of Special Relativity. The relativity of simultaneity means that if an observer observes a succession of events then another observer who is moving relative to the first may observe these as events laid out in both space and time.

The image shows how time and space are related

Given that a sequence of events for one observer can appear as events spread out in space for another observer any questions about time also become questions about space. The question "does time exist?" is also asking "does space exist?".

For a given observer time is an independent direction for arranging events. A bit like space but it enters the metric of space-time with an opposite sign to that of spatial dimensions - see https://en.wikipedia.org/wiki/Spacetime.

Your question was about how we experience time. The experience of time is like the experience of space: how do we experience space? The experience of space, such as the background of this text, is a simultaneous set of events surrounding an apparent observation point. How is that done? Answer that question and you will answer the problem of space and time perception. The clue is in the word simultaneous. There is too much to explain further here, see https://drsimonrobin.substack.com/p/our-reality for many of the answers.

I have been asked to explain a bit further.

Notice in the top right graph in the illustration above that the x-axis of the moving observer crosses several events in the "stationary" observer. These events, which were successive for the stationary observer are simultaneous for the moving observer.

Suppose we have a line of events arranged in space. The physics of simultaneity tells us that these events could be successive events for another observer. The events which, in one frame are separated by time are separated by space in the frame of reference of the moving observer. They are the same events in both frames. What has happened is that there has been a rotation in four dimensional spacetime - a bit like things can rotate in 3D. (The rotation is possible because the 4 dimensions are part of the same 4D pseudo-Euclidean manifold. https://en.wikipedia.org/wiki/Manifold).

If spatial length can be interchanged with temporal length then we cannot simply wish time away. See https://en.wikibooks.org/wiki/Special_Relativity/Simultaneity,_time_dilation_and_length_contraction for a simple introduction to relativistic simultaneity.

This analysis tells us a great deal about physical time. Could we find an animal that did not know time or had a different time from physical time?

We can use clocks to show that we are not aware of any mental processes that take no time. Knowing is a mental process so knowing without time would be nigh impossible.

Processes occurring without time are not entirely impossible but they would entail components that are outside of spacetime - outside of both space and time because spacetime is a continuum. If we are allowed to stray outside of spacetime then the possibilities are unimaginably infinite so the original question would have no definite answer.

  • how did you do the graph?
    – user67675
    Nov 20, 2023 at 17:56
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    – Meanach
    Nov 20, 2023 at 19:18
  • When you edit on stack exchange there is an add image icon. Click on this and then click on the pop-up. A data entry box appears that looks like it is for text, paste your image into this. Nov 21, 2023 at 9:40

I think your intuition is self-evidently correct- animals must have some experience of time just as they must have some experience of space. So either Kant's claim was incorrect or perhaps he had something else in mind when he said that time was pure intuition- perhaps he did not meet that it was wholly a product of the human imagination. What I suspect, but cannot prove, humans do which animals do not is to speculate on the nature of time in a more abstract sense, and it is perhaps that aspect of time that Kant treats as the product of the human mind. Time and space exist in some sense, as they are indispensable to our understanding of the working of the Universe. Curvature of space and time explains why apples fall to the ground, and our best models of the Universe suggest that more than thirteen billion years of time elapsed well before there was a single human to imagine what it was.

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