Lucretious, in his poem de rerum natura had atoms moving through the void. It seems at least from a modern perspective that his void is what we would call space.

The interesting question, which I have asked here is did anyone in antiquity discover or intuit that space itself must be something.

Now, Parmenides denied the reality of void. This leads one to suppose that he would have discounted Lucretious' void as a true void. It certainly is. Hence, one is led to the thought, that space is not a nothing but a something.

Obviously, this thought is retrospective. It takes Parmenidian ideas and applies it to concepts which have only been elucidated now. In particular, it is only since Einstein that space has been taken for a thing and not a stage, though in actual fact the thought can be traced earlier to Clifford after Riemanns ideas on space & geometry was elucidated. Of course, Einsteins description is quantitative, following the tradition laid down by Galileo; and Milesian science is purely qualitative.

Still, it seems Parmenides was concerned with a very basic analysis of what it means to be and to be not, with motion, and thus space.

Is there any evidence in Platos Parmenides that backs at least some of this up; or elsewhere?

2 Answers 2


We have a good number of fragments that are attributed to Parmenides himself. Specifically regarding the void, Parmenides asserts that you cannot separate what is from what is, because doing so implies a something that is not. Since what is not is not, it can't be used as a property of difference. Thus, there can't be any difference in the world, which implies a pure monism.

It then further implies that there is no motion, because that would require a difference in location, but we can't have a difference of any kind. By the same logic, we have no motion, indivisiblity, one-ness, and sameness of all things.

In Plato's Parmenides, we see Plato's take on Zeno as a type of negative proof for Parmenides' monism, but that's a slightly different story. When reading Plato's book though, there are some questions surrounding if what is referred to in Part I and Part II are the same thing (Parmenides' Monad vs Plato's One-ness the form).

I would suggest reading the fragment's of Parmenides' poem and Zeno's paradoxes prior to reading Plato's Parmenides.

  • I'm familiar with zenos paradoxes and the fragments of the Parmenides poem. I find Platos Parmenides difficult. I'd venture that the atomists tried to broker a middle ground between the pure monism of Parmenides and the Heraclitean flux of phenomena; in fact each democritian atom seems to be a Parmenidian one, intriguingly. Commented Sep 20, 2013 at 7:30
  • Although you've admirably explained Parmenides monism, it doesn't quite answer my specific question. This maybe because Parmenides did not directly state it, but surely from your description, it must imply that space is in fact not a void, and therefore must be something; for surely Parmenides was addressing the real world, even though the relation between the his monism and the world as it stands in relation to us is unclear, and possibly not addressed in his poem, or more likely lost. Commented Sep 20, 2013 at 7:34
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    Aetius (Placita 2.7.1) writes that Parmenides says that the world is the whole (monism) that is partitioned by the human mind into interwoven rings/spheres. For P., his cosmological construction was directly influenced by him monism, and thus, there is no void.
    – jacob
    Commented Sep 22, 2013 at 2:07

From Parmenides's On Nature:

Come now, I will tell thee - and do thou hearken to my saying and carry it away - the only two ways of search that can be thought of. The first, namely, that It is, and that it is impossible for anything not to be, is the way of. conviction, for truth is its companion.. The other, namely, that It is not, and that something must needs not be, - that, I tell thee, is a wholly untrustworthy path. For you cannot know what is not - that is impossible - nor utter it;

His objection to non-being does seem, as you supposed, an objection to a clear paradox (i.e. a non-being being). This is a very formal and verbose objection (it's Parmenides), stating something cannot be both not P and P. So, then, what is being? Or, as that's a very broad question, what is 'space'? I'll propose three relevant definitions.

Defining it first as a kind of matter, the four elements were well accepted. So, space around us (air) was a thing. Aristotle (in Meteorology) mentioned Aether as the divine air that took up what we consider outer space. He mentions that Anaxagoras considered it filled with fire. So, outer space was also a thing.

A second definition regards dimension. Space can refer to the volume that an object fills, the surface it has, etc. Plato loved this kind of space. It clearly exists.

A third definition is 'nothingness'. No properties, no nothing. This is the definition that Parmenides seems to be using. It's solid, but not particularly useful. Nothingness, by definition, cannot exist (as half-seriously shown by "no nothing"). Doesn't stop him from thinking about it though.

As for the Atomist 'void', it seems to qualify more as the second definition. It has dimensional properties, and so can meaningfully be discussed. Atomism allowed for the flux (change) of Heraclitus as well as the permanence of Parmenides. That is, atoms change over the eternal void.

You're right that we should not read too much into this, but they all do grapple with our complete inexperience with nothingness. Parmenides was very fond of permanence, as a being with a beginning implies that it was a non-being being before its beginning.

To finish half-answering your question, Aether theories of one sort or another lasted until Maxwell and Einstein, who replaced aether (definition 1) with a field (definition 2). Quantum physics helps complicate things even more. When we find that nothingness has properties, we make it something.

  • Parmenides wrote a poem, and what comes across, to me at least, is a grand, high and ornate tone; rather than a formal & verbose. I think your definition of nothing is something that Parmenides would object to. He says quite clearly 'you cannot know what is not - nor utter it', a definition in the proper sense is not possible. Dimension is somewhat anachronistic, but of course the greeks implicitly recognised it. Although the traditional history is that the idea of a field replaced the aether; I'd simply say that they refined it. This was a continuity is established between the older Commented Sep 20, 2013 at 7:44
  • theory and the newer. The salient feature of both theories, for me, is that they both fill space. Aether was introduced by Plato as a kind of refined air, and by Aristotle as a fifth element that filled the celestial sphere, after Newton it became mechanical and after Einstein & Maxwell a field. Commented Sep 20, 2013 at 7:52

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