51. Why Time Might Not Be Real

Probably one of the most counter-intuitive notions has been raised within the title of this article; why time may not be real. Yet, in 1908, the British idealist philosopher J.M.E. McTaggart (1866-1925) wrote a paper entitled ‘The Unreality of Time’ which intended to disprove the existence of time. McTaggart himself recognised that it is “doubtless paradoxical to believe that Time is unreal” but he also noticed that this belief “has proved singularly attractive.” Bearing these details in mind, we can begin to summarise his argument and see whether it has stood the test of time (hehe).

The first part of McTaggart’s paper is to demonstrate that there are two ways of viewing time, his distinctions are between what he called the ‘A series’ and the ‘B series’. The ‘A series’ essentially states that there are three different characteristics of time, which flow into each other; past, present and future. The ‘B series’ states that positions of time are always earlier than or later than another time position. It is of paramount importance to believe that change exists, since as he states, “a universe without change would be a universe without time.” McTaggart then performs some metaphysical gymnastics and suggests the following:

“No event can cease to be, or begin to be, itself, since it never ceases to have a place as itself in the B series. One event cannot change into another.” – J.M.E. McTaggart.

Change now seems possible without the A series, but the B series by itself does not distinguish between past, present and future, so it is insufficient by itself. With the A series we are forced to the conclusion that all change is but a change of characteristics, i.e: an event was in the future, then it was present and then it became past. McTaggart has shown that without an A series, there could be no change, but such a notion is so counter-intuitive to our perceptions of time. McTaggart now seems reasonably comfortable in suggesting that the A series is pretty essential to time.

But McTaggart is not finished yet. In the second part of his paper, he pokes the reader with the next logical step in his argument to show that “If the distinctions of time are never true in reality, there is no reality in time.” McTaggart’s aim is to somehow disprove the A series. He starts by suggesting it is contradictory for any event to simultaneously possess pastness, presentness and futurity. Seems pretty reasonable. Interestingly enough, these three characteristics are mutually incompatible and yet true of every event. Our language with its tenses seems to explain away this difficulty, since we say of an event that “it is present, will be past and has been future.” But that doesn’t seem right, we are presupposing the very thing whose nature we are disputing; we are using ‘time’ to talk about time. Stick with me. Getting back to McTaggart’s argument, we are really saying that an event is presently in the future (‘present-futurity’), then it will be in the past (‘future-pastness’) and this event used to be in the future (‘past-futurity’). However, an event cannot have all of these characteristics at the same time. These characteristics are also incompatible, since ‘future-pastness’ suggests an event is in the future and ‘past-futurity’ suggests that this event is not in the future. This is a vicious circle, and in this way McTaggart has shown that the A series is quite contradictory, and since the notion of time relies on the A series, we must reject the A series and subsequently reject time.

McTaggart’s paper was a landmark in the fascinating and understudied philosophy of time. To this day his paper contains a robust and relatively reasonable argument. What seemed at first to be highly paradoxical – on McTaggart’s own admission – is now fairly intuitive. John McTaggart was a peculiar philosopher in his own right, known to “walk with a curious shuffle, back-against-the-wall, as if expecting a kick from behind.” Up to now, no such “kick” has been delivered, but it doesn’t necessarily mean that he is right. McTaggart himself claimed that: “Time must be rejected, not because it cannot be explained, but because the contradiction cannot be removed.” In any case, if you are feeling quite nauseous, or have a throbbing headache as I did after I read his paper, bear in mind the following quote from our old friend, Aristotle:

“It is the mark of an educated mind to entertain a thought without accepting it.” – Aristotle.


  • (1908) “The Unreality of Time” by John McTaggart Ellis McTaggart.
  • Geach, Peter, 1979. Truth, Love and Immortality: an Introduction to McTaggart’s Philosophy, Berkeley: University of California Press.
  • “The Persistence of Memory” by Salvador Dali.

6 thoughts on “51. Why Time Might Not Be Real

  1. Of course time is nor real! And of course it is as real as reality itself! The notion of time is a human construct and always has been. The perception of time is perceived differently in each moment of perception depending on the states influencing the process of perception itself. And yet, entropy always increases unidirectionally and inexorably. There’s no way around that, and that’s enough to define the arrow of time for all observers. But all that stuff about events and past, present and future, is just child’s play and plain silly. Just turn to modern physics and in particular the mathematical framework for the special and general theories of relativity and you’ll find all the answers you want about the relationship between past, present and future; the fact that all of these are relative to an observer and cannot be treated in absolute terms; that events in the physical world are defined in space and time; that space and time are aspects of each other, and that motion, matter, energy and radiation all intermingle in their influence on the shape of space time and therefore on the lengths of meter stick and rates of running clocks. I like philosophy, but physics should be treated with the most appropriate mathematical frameworks developed today in which real measurements and real observations can be made to verify the behaviour of space and time. And we really always have to be careful about not getting confused by the words and definitions we use for certain things like events, past, present and future, and time. So, if you’re serious about getting to the bottom of this, get on the study of General Relativity even if it is not in order to do calculations with full mathematical rigour. But surely, the sooner your start the better off you’ll be because it’s not that straight forward 🙂


    1. Thank you for your comment.

      To say “of course time is not real” is somewhat of a gross oversimplification of the matter, don’t you think? It’s not at all common-sense to doubt one of the things upon which your existence certainly depends. I wouldn’t call it child’s play either, like you said McTaggart was definitely not up to date with his understanding of physics, but this certainly doesn’t place his work within the domain of ‘silliness’. We’re dealing with one of the fundamental aspects of reality and, as much as I may like the sciences, philosophy shouldn’t be belittled just because it doesn’t have “real measurements”. The whole development of analytic philosophy in the 20th Century lends credence to the importance of logic and how philosophy is advancing more towards rigorous frameworks and not the other way around. In any case, physics and philosophy delightfully complement each other, if I might modify an Einstein quote: “Science without philosophy is lame, but philosophy without science is blind.” Epistemological skepticism is a gift to the physicist just as logical and mathematical precision is a gift to the philosopher. To your last point, I definitely want to advance my understanding of general relativity, if you have any suggestions please let me know 🙂

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      1. You’re right. I’m sorry I was cutting and unfair. And to be clear, I am definitely of the opinion that philosophy is essential in science. And to be even more explicit, it is only when I went to the philosophy department at McGill in my 3rd year that I met what I considered to be true scientists. It wasn’t in the physics department! Those professors in the philosophy department all had first done their PhDs in physics, in math, in biology, and then did a second one in philosophy of science. That, I thought, was very impressive. What I mean by true scientist, and of course these professors considered themselves philosophers and not physicists or mathematicians, is really just a person that asks profound and difficult questions and seeks answers to them. Until the 50’s-60’s, basically all physicists and mathematicians, thought deeply, read philosophy, and were philosophers themselves. This changed with the birth of Big Science and especially Particle Physics and all the other branches of applied physics that required a large amount of man power and, therefore, specialisation. The trend away from philosophy has only intensified with time, and I don’t see any reason to hope for a turnaround. It simply won’t happen. I get impatient when I see philosophy about things that I consider already well understood in a fundamental, physics-kind-of-way. And for me the existence or non-existence of time is one such subject. There are many examples of ways in which we can measure time objectively, the most used for precise clocks is the radioactive decay of unstable elements that have absolutely no idea we’re watching them and just do their thing. The next thing in precision will be a pulsar timing array where we will use the spin rate and spin-down rates of a large number of known pulsars (especially ms pulsars) in all directions of space, correlating all the signals from them to have the ultimate high precision clock with absolute timing accuracy that is mind boggling, and with the purpose of also measuring gravitational waves that would pass through and skew the spacetime and therefore change the timing slightly. Anyway, the point is, of course time in the sense of being something that can be quantised in measurements of a process that evolves in a particular direction completely independently of us is real. At the same time, the fact that the perception of time is different under different circumstances makes it a subjective thing, so time as sometime perceived is whole malleable in nature. And all of this set in the context of General Relativity tells us that even the real physical ticking of clocks is never absolute and depends on the metric tensor (defines how distances and times are measured), which in turn depends on the motion and on the stress-energy tensor defined by the distribution of matter/energy/radiation. So that in a very real sense, the faster you move the slower your clocks, and the stronger the gravitational field (the curvature of spacetime) the slower the clocks. And the catch that you do not perceive this because for you they click at the same rate. It is the other observer watching from a distance that sees your clocks running slow, and I mean see the rate of radioactive decay slowed down due to your motion and the curvature of spacetime. Anyway, this is much too long a comment already. In summary, I’m sorry I was unfair and demeaning. Historical work is important to consider. I am a bit of physics snob, but that’s only because I can afford to be 🙂 I think that in this day and age, deep-thinking scientists are found in philosophy departments mostly and rarely in physics departments; and in the end, I retain the right to get aggravated by philosophising that seems to me of little value in progressing towards a deeper understanding of whatever is it that is being discussed. My bias here is that I believe a philosopher of physics must be a physicist not in the sense of working as one, but in the sense of having studied physics, and not just in high school, but really studied physics out of curiosity and interest for it and in order to understand. It is not necessary to have formal training because self-teaching is very powerful. But I don’t want to listen to someone philosophise about quantum mechanics and the uncertainty principle when they have not worked through a graduate level course in QM, or philosophise about space and time when they have not worked through at least an introductory course in GR. That’s what I mean. About recommendations, if next year when you’re off to university, you still want to and have the time to study GR, I’ll recommend something for you. Until then, you need to concentrate on other things.

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      2. I completely understand where you’re coming from; of course I am an amateur when it comes to the philosophy of time and pretty much physics in general (Biology’s my science, I admit). I think, like you pointed out, there is a very important distinction between objective time and the perception of time; this I will definitely take into account. That being said, my mission behind this article was to highlight some of the thought behind why time might not be real. McTaggart clearly was unaware of quantum physics and had he lived about 20 years longer, his thought would’ve been blown apart by Heisenberg and other such thinkers. I do agree that you should have the right to be annoyed by philosophising which disregards science and perhaps I should consider trying to ground some of my philosophy in scientific rigor. I fear my articles are no longer in the criterion of ‘philosophy in seconds’, in reality they belong to ‘philosophy if you have a couple of minutes’ (not as catchy, but sure).

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  2. Oh, and I forgot to write that Einstein’s special relativity was published in 1905, and therefore by 1908 when McTaggart wrote his essay, a lot of serious discussion and maths had already happened around all these “philosophical” questions about the notion of simultaneity, past, present and future, the change from absolute time and space to times and spaces all relative to observers and their state of motion, etc. So, clearly McTaggart wasn’t up on the physics of the day, it seems, at least not when he wrote that piece. Other contemporaries concerned with these questions included Hendrik Lorentz and Herman Minkowski. Herman Weil was also very seriously involved in all of this since the start. Of course, all these guys were first mathematicians and physicists and then philosophers; not the other way around. That makes a big difference, at least in my view.


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