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The Greeks

An Ancient Conversation About Motion

Matei Tanasă imagines the sort of conversation about change, motion, appearance and reality that philosophers were having in ancient Athens.

(Heraclitus, Parmenides, Zeno, and Pyrrhon are sitting at a table in Athens. A worried looking Athenian approaches.)

Athenian: Oh, you who are the wisest of men, I long for freedom from illusion, the hardest of chains and cruellest of servitudes!

Heraclitus: Tell us your problem with no hesitation. We gladly help the ones who seek for knowledge.

Athenian: I have heard it said that many philosophers claim that movement – that which seems most evident of all – is not real, but a mere phantasm. Tell me now, you with the brightest minds, is this so or is it not?

Parmenides: You came to the right place, friend, and I shall answer your question. Tell me, is it not true that if something moves, it either moves itself or is moved by another?

Athenian: Indeed.

Parmenides Changing Yet Unchanging by Clint Inman
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Parmenides: Yet all that moves does so as a result of either pulling or pushing, may it be in whatever direction. So, if something moves itself, something needs to either pull or push itself. But something cannot be behind itself, nor can it be in front of itself, above itself, or under itself. Thus nothing can push or pull itself. Therefore, nothing can be moved by itself.

Athenian: You seem not to be wrong.

Parmenides: So, the only way in which something can move is if it is moved by another. Yet nothing can move something if it does not itself move first. Since the mover needs to be moved, we need a second mover to move the first. The same we need for the second mover. And so we need an initial mover that is moved by nothing other than itself. Nothing can move itself, as said already, so such an initial mover cannot exist. Thus there is no movement, and any movement you may think you see is a mere illusion.

Athenian: By Zeus!

Heraclitus: But, Parmenides, how do you know, I wonder, that the only way in which something is moved is either by pushing or by pulling? It is true that these are the only ways we have seen; yet from this we cannot say they are the only ways that exist. Even more, I have heard that Democritus claims movement to never have started, yet exists. So movement, even if it is only a result of pushing and pulling, does not actually require an initial mover.

Zeno: May it be as you say Heraclitus. Let’s assume that Socrates moves from place A to B. It seems clear that he would have to pass through the middle, place C, in order to get to B. Yet in order to get to place C, he would have to pass through the middle of the distance between A and C – let’s call that D. But the same we can say about the distance between A and D: that he would have to pass through the middle of that distance, too. And in this way we can continue forever. So it is clear that in order to get from place A to place B, Socrates would have to pass an infinity of places, which would take an infinite amount of time. It follows, then, that no movement is possible.

Heraclitus: But what if all things move by a specific distance – let’s say the distance between X and Y – and so they do not need to pass through all the points between, but instead jump directly from X to Y?

Zeno: That, Heraclitus, seems unbelievable.

Heraclitus: More unbelievable than the absence of movement, I wonder?

Zeno: If you are right, then this movement from X to Y would either be instant or it would take time. If it is instant, then the result is that all things get anywhere instantaneously, for all things would just repeat this instantaneous movement to get anywhere, which is absurd. Yet if the movement from X to Y would take time, then in the time in which the movement takes place, the object would either be in place X, in place Y, in both, or nowhere. But if it is in place X it has not yet started moving, and if it is in place Y is has already finished moving. The object cannot simply disappear then reappear. So this means that it is in both places at once – which is, again, absurd. Let’s, however, forget all this and assume that you are right. Tell me, then, can an object act in a place where it is not?

Heraclitus: It cannot.

Zeno: Then where does an object move – in the place in which it is, or in the place in which it is not? Something cannot do anything in the place in which it is not. Yet if it moves only in the place in which it is, it does not move at all!

Heraclitus: What about the sphere? If you rotate it perfectly, it moves – yet it does not change its place.

Parmenides: But the parts of the sphere change their place, do they not?

(Heraclitus does not answer. There is a moment of silence.)

Athenian: Oh, Zeus, what have I come to hear? Have I lived in a mirage all my life?

Heraclitus: Tell me, Parmenides, do not our representations of the world change? For example, earlier today it appeared to me that we were walking towards this table, now it appears to me that we are sitting at it.

Parmenides: Indeed, the appearances change.

Heraclitus: Yet the appearances are either the result of the relation between an object and ourselves, or they are simply the product of our own minds, with no actual object corresponding to them.

Parmenides: I agree that those are the two options.

Heraclitus: If appearances are the result of the relation between an object and ourselves, then if the appearances change, it follows that either the world, ourselves, or both, change. And if the appearances are simply the product of our own minds, then it means only we change. But in both cases, change exists. But if there is change, then there must be movement.

Parmenides: How so?

Heraclitus: Well, it seems clear that if a part changes, the whole changes.

Parmenides: Indeed.

Heraclitus: So, if anything changes, then the group containing all the things that exist changes. Let’s call this group, ‘ That which is’, by which is meant, everything that is. Yet there are only three ways in which something can change: by adding to it, by subtracting from it, or by repositioning its parts.

Parmenides: I cannot think of any other way of change.

Heraclitus: But nothing can be added to That which is, for nothing exists exterior to it, and nothing can be subtracted from it either, for nothing which is can become something which is not, as you yourself claim.

Parmenides: I agree. No thing can turn into nothing, and no thing can come out of nothing.

Heraclitus: But if that is the case, and change exists, then the repositioning of the parts of That which is must be possible. Yet we cannot talk about changing position without movement, for that is absurd. Therefore, movement exists.

(Parmenides and Zeno remain silent.)

Athenian: Oh the merciless gods! I came here to find answers, yet deeper in questions I’ve sunk! What should I do when I have heard such good arguments, some proving, some disproving, the same thing?

Pyrrhon: Suspend judgement.

Matei Tanasă is a student at August Treboniu Laurian National College in Romania. He was first philosophically challenged by Plato’s Apology, which he read during train rides to school in Sweden.