The Circus of Time

Point to the Circus Act

Imagine that you have befriended an alien from outer space who knows very little about human culture. In an effort to show them around, you take them to a circus. During one act, as an aerialist is climbing and twisting up suspended bits of fabric, your alien friend asks: “Is this the aerial act?” You explain, in a hushed voice, “yes.”

Life Visits the Circus in Florida- Acrobat Performer Nina Leen—The LIFE Picture Collection/Getty Images

But then a few seconds later, the alien asks, “Ok but then what is this? Is this the aerial act?” You respond, “Yes, this is still the aerial act.” Confused, the alien waits a minute and asks, “But wait. If all of that, before now, was the aerial act, then what is this thing that we’re watching now, right this second?”

Puzzled, you try to explain, “all of this is the aerial act. All of what we’re seeing now, and what we were watching a second ago, and what we were watching a minute ago, and what we will be watching for a few minutes from now. This whole thing is the aerial act.” You gesture with your arm to try to encompass all of the moments that compose the aerial act.

The alien looks around, concentrating very hard on where you’re gesturing, befuddled. “But I don’t see what you are pointing to. The moments that have been, that you said a moment ago were the aerial act, have now gone – they aren’t here, we can’t see them. The moments that are coming, that will be, which you say are also part of the aerial act, have yet to be – they aren’t here, we can’t see them. So when or where, exactly, is the aerial act? Can you please point to it?”

What do you say? Can you point to the circus act – the whole thing? Why not?

Our usual (human) understanding of a circus act is of something that spans across time. It is something that has duration. A circus act can be anywhere from one minute to one hour. The particular length isn’t important. But there has to be some kind of temporal length to it: no circus act takes place in an instant.

What we (humans) understand – which our alien friend does not – is that circus acts, like other events (music performances, play productions, movies, baseball games, senate confirmation hearings, and so on), are things that are stretched across time. No one of these things can exist in an instant or be fully present in a snapshot. Our alien friend is confused, it seems, because they are assuming that things such as circus acts fully exist in a single moment; we should be able to point to something, right now, and have the object of our pointing be the full extent of the thing that exists. It should all be there, the alien assumes. But in fact there are many things – circus acts, plays, movies, etc. – that we think exist but do not exist in a single moment. You cannot point to an entire circus act because, in it’s entirety, it is never fully in front of you in the way that, say, a painting or a car is.


Maybe not surprisingly, philosophers have thought (and do think) a lot about this issue. Let’s take a minute to get clear on some terminology, introduce some philosophical views on time, then we’ll come back to you and your alien friend.

The Ontology Box and Time

One area of study in philosophy is known as ontology – the study of what there is. We talked about this a couple of weeks ago when we read Quine’s “On What There Is” (see Class Notes – Week 6).

You might think that the study of what there is would be rather uninteresting. To find out what there is, just go out and look: a car, a cat, a running shoe. DONE. What’s so deep and interesting about that?

But as you’ve probably realized by now, questions or topics that may initially seem trivial or simple, are not so trivial or simple upon some reflection. So, let’s talk about what there is. And let us introduce a toy strategy for doing so.

Imagine that you have something called an “ontology box.” Everything that you think exists in the world is in this box. Each person has their own box, and each box will differ with respect to the contents in this box, depending on what each individual thinks exists in the world.

Suppose two friends, Gary and Larry, have different worldviews. Gary believes that God exists, but Larry doesn’t. Larry believes that the Loch Ness Monster exists, but Gary doesn’t. On everything else, Gary and Larry agree: they both believe that puppies, cars, and milkshakes exist; they both believe that the Tooth Fairy and Santa do not exist.  

One way to describe the difference between Gary and Larry is to imagine that their respective ontology boxes are different: Gary has God in his box, while Larry does not. Larry has the Loch Ness Monster in his box, while Gary does not. Both Gary and Larry have puppies, cars, and milkshakes in their boxes, but neither have the Tooth Fairy or Santa.

Now think about your own ontology box. What’s in it? Probably puppies, cars, and milkshakes. Maybe not the Tooth Fairy or Santa. Maybe God is in there, maybe not.

But what about time?

Most people think that time exists. We tend to think of ourselves as creatures who exist in time. We talk about being in the present, and living in the moment. We talk about time passing, about time going fast or slow, and about time standing still. We talk about time flowing. We talk about killing time, and wasting time; we say that time flies.

Are these all just metaphors, or do we really think that time exists in a way that allows for it to flow, pass, or as something that can go quickly or slowly? What is time? Does it exist? Is it in your ontology box? 

Maybe it will help to think about different aspects of time. Start with NOW. Surely, the present moment exists. What other time are we living if we aren’t living now? But are we always in the present moment? When isn’t it right now?

What about now?

Or now?

What about the past or the future? If the past doesn’t exist, why do things that have happened have an effect us? Why care about past events if they don’t (or no longer) exist? What about the future? Does the future exist? If you think it doesn’t, why care about decisions now that will have consequences later? Do you think the past or future exists in the same way that the present moment does?


Let’s look at some different philosophical views on time, and see if they can help navigate us through these questions.

Metaphysics of Time

Some people think that the past, present, and future are all equally real. This view is called eternalism. To grasp this idea, imagine that time is stretched out in the way that graphic timelines often represent it: all moments are mapped out equally – all at once, as it were. A plot on the line is just one temporal moment of many, and no single moment is privileged over any others. Whether a particular moment in time is past, present, or future is relative to one’s position in time (or on the timeline), just as what is right or left or above or below is relative to one’s position in space. In this way, the past, present, and future all exist, just as left, right, above, and below exist; they are all equally real. 

An alternative view is to think that only the present moment exists. This view is called presentism. You might think that this view is true because we can never ‘see’ the past or the future. We are always in the present moment – it is always NOW . There is no reason to posit the existence of times that we cannot see or access. Our alien friend might be tempted towards this view: the alien had difficulty comprehending how something could exist beyond what is presently happening, and what we (presently) observe. According to presentism, there is no past or future; the only things that exist are those that exist presently.  

Another view – the growing block view – claims that the past and the present exist, but that the future does not. You might think that this is view is true because, intuitively, we have asymmetrical attitudes towards the past and the future. The past, we tend to think, has already happened, and there is nothing that we can do to change it. “Don’t cry over spilled milk.” “What’s done is done.” These expressions indicate a belief that everything in the past is already set, has already happened, and cannot be changed.  The future, however, we tend to think of as not yet being settled. Most of us do not think that it is settled yet whether or not you will have a grilled cheese sandwich for lunch tomorrow. In contrast, we do think that it is settled whether or not you had a grilled cheese sandwich for lunch yesterday. According to the growing block view of time, time is like a block that is growing as time passes. Past events exist, and are continually being ‘added to’ as the block moves ‘forward.’ The present is the ‘growing edge of being’ at the edge of the continually growing block. The future is open, and has yet to be; it doesn’t exist.


Finally, let’s consider the moving spotlight view. This view claims that the past, present, and future all exist, but that they are not all equally real. The present moment, moving spotlighters claim, is special. It is more robust, more real, more highlighted, than the past or the future. Imagine a giant spotlight moving across the horizon. The present moment is the spotlight, the past is whatever used to be in the spotlight (but is now in shadow), and the future is what has yet to be in the spotlight (but, until then, is unlit). This view aims to capture some of the intuitions we have about the present moment: namely, that we seem only ever to immediately experience the present. Yet it also avoids some of the difficulties of denying that the past and future exist (as presentism does). 

Time permitting, we will be discussing advantages and disadvantages of each of these views in class. But the above brief descriptions will hopefully be enough for our purposes here, and will help you to think through your own thoughts on time.  


Let’s return to you and your alien friend.

And, for the moment, let us assume that eternalism is the correct view of time.

If eternalism is the correct view of time, how should we think of objects in time? How should we think of extended events, such as the circus act you and your alien friend are watching? And how should we think of ordinary objects, such as milkshakes and cars, or human beings and aliens?

One view, called Four-Dimensionalism,  claims that nearly ALL objects are extended through time the way a road is extended through space.

Imagine that you take your alien friend along Main St, point to it and say “This is Main St.” You then walk a bit further, point to the road you’ve been following, and say “And this is Main St.” This does not seem puzzling to us because we understand that a road is not located in any one spatial location. Yet your alien friend is unfamiliar with the convention of roads. Confused, they ask, “But wait. If all of that, over there, was the road, then what is this thing right here that you’re pointing to?”

Puzzled, you try to explain, “all of this is the road. All of what we’re seeing here in front of us, and what we saw over there, and what we will be seeing when we get over this hill. This whole thing is the road.” You gesture with your arm to try to encompass all of the spatial bits that make up the long road.

Our alien might be confused if they think that whatever you are pointing to must be fully present in one spatial location. If our alien friend doesn’t understand how certain objects can be spatially extended, and take up many points of space, then they will be confused as to how it is that a road can exist here, and there, and also way over there.

Similarly, as we explained at the beginning of this post, if your alien friend doesn’t understand how certain events can be temporally extended, and take up many temporal moments, then they will be confused as to how something (like a circus act) can exist a moment ago, and now, and several moments from now.  A circus act, a play production, a music performance – none of these things exist in a single moment; they are smeared across a bunch of moments. Someone who doesn’t get that will have a hard time understanding what an extended temporal event is.

So now I want you to imagine that not just certain events – such as circus acts – are extended through time, but that ordinary objects such as milkshakes and cars (and human beings and aliens) are temporally extended as well. What would that mean? 

For one thing, it would mean that an object such as a car or human being does not completely exist in any one moment. When you are hugging your friend, you are not hugging all of them, for they have many temporal parts at other temporal moments that you aren’t hugging. When you drive in your car, you are not driving your car in its entirety – there are past and future parts of your car that you are not driving. Ordinary objects, if they are spread out in time the way roads are spread out in space, are very rarely fully before us.

For another, an ordinary object is very rarely fully participating in an activity or instantiating a property. For example, are you sitting or standing? If four-dimensionalism is true, then you – the fully temporally extended object that is smeared across many moments from your birth to your death – is neither sitting nor standing. You may have a temporal part that is sitting or standing, but the temporally extended object is neither.

What other consequences are there for this view? How would such a view of objects make sense of objects going into and out of existence? What would it say about birth and death?


There is much more to say here. In particular, there are other views of time, and many other theories of how objects exist in time, to explore and discuss. But hopefully this has given you some things to think about. What advantages can you see for four-dimensionalism? Any disadvantages? If you dislike the view, what other way of thinking about objects in time makes sense to you? If you like the view, why do you like it?



Suggested Reading

**Originally published Dec. 08, 2017; updated Oct. 30, 2018

Got thoughts?