For Aristotle, there is no separate void. It is thought that if there is movement of simple bodies, then the void must exist. In particular, if one body moves toward or upward, it is because there is a void. So, it is thought to be a sort of place deprived of body. Aristotle casts a doubt on this argument by asking where moves a void when a body takes its place. Is this inserted body into the void considered to be in place or in the void? Those who defend a thesis of an existence of void would say that a body is carried into a separate place where there is the void. Let’s consider that a body as a whole is placed in a separate place. The problem with this statement is that a part of the body will not be in a place but in the whole. If we believe that a body is a part of the universe, then it will be in the whole as well. So, separate place does not exist. If it does not exist, neither will void.

Saying that if bodies move then the void must exist turns out to be the opposite. How then these bodies move in the void? In the void things must be at rest, for there is no place to which things can move more or less than to another. If void is uniform, then it admits no difference. Further, if we consider that all movement is either compulsory or according to nature, how then movements can be differentiated in the void? There is no difference in what is nothing. However, natural locomotion must be differentiated. Otherwise, nothing has a natural movement, or else there is no void. Finally, it is thought that a body moves into the void because it yields. How then a body moves into only one direction? The void should yield equally everywhere, so that things in the void should move in all directions.

The same argument applies as against those who think that the void exists because we see the same weight or body moves faster than another. There is a difference in what bodies move through, as between water, air, and earth or the moving. There is also a difference in weight of bodies which may explain why some bodies move faster then others. Aristotle argues that if there is some ratio of lightness between bodies, this is not possible that this ratio is the same in the void. Why one body should move faster than the other in the void? It should differ in no respect from the other.

In conclusion, Aristotle refutes all arguments of the existence of the void. He argues that we cannot posit the void in a separate place, as the latter does not exist. In addition to it, a movement of bodies in respect to place shows the opposite of what the proponents of the void state. If the void existed, the bodies would move in it and through it in a different way.

Bibliography:

  • Aristotle, Physics Book IV, Chapter 8 in The Scientific Background to Modern Philosophy, Selected Readings, Edited by Michael R. Matthews, Hackett Publishing Company, Indianapolis/Cambidge, 1989.