Parmenides · Philosophy
Parmenides’ doctrine of the two ways of inquiry - the Way of Truth (‘It is’) and the forbidden Way of Not-Being (‘It is not’) - and his momentous denial of the void, the empty space that the Atomists would later resurrect to rescue motion and plurality.
At the heart of Parmenides’ poem stands a stark choice between two paths of inquiry, presented by the goddess as the only two ways that can even be conceived. The first is the Way of Truth: ‘that It is, and that it is impossible for it not to be.’ This way, the goddess says, is the way of conviction, for truth accompanies it. The second is the way of Not-Being: ‘that It is not, and that it must needs not be.’ This way, she declares, is utterly impassable - ‘a path that none can learn of at all,’ for ‘what is not’ can neither be known nor uttered. To set out on the second way is not to reach a false destination; it is to set out on no road at all, to think nothing, to speak nothing.
This sharp fork - between the thinkable ‘It is’ and the unthinkable ‘It is not’ - is the engine of Parmenides’ entire philosophy. Everything follows from closing off the second way. If ‘what is not’ cannot be thought or spoken, then it cannot figure in any account of reality; and since change, plurality, and motion all seem to require ‘what is not’ (empty space to move into, the not-yet for things to come from, the not-this that separates one thing from another), all of these are ruled out along with it. The two ways are not two competing theories to be weighed; one is the only possible way of truth, and the other is a blind alley that the careless mind only imagines it can travel. The discipline of philosophy, for Parmenides, begins with refusing the second way - refusing to let the mind drift into the illusion that it can think ‘nothing.’
One of the most consequential applications of Parmenides’ logic is his denial of the void - empty space, the ‘nothing’ between things. To common sense, and to physics, empty space seems obviously real: things move through it, are separated by it. But for Parmenides, empty space is precisely ‘what is not’ - a region where there is nothing - and since ‘what is not’ cannot be, there can be no void. Reality is a plenum: completely full, with no gaps, no empty space, no nothingness anywhere. Being is ‘whole and continuous,’ for any gap would be a patch of not-being, and there is no not-being.
This denial of the void has a devastating consequence for motion. For if reality is completely full, with no empty space, then there is nowhere for anything to move into - every place is already occupied by Being, and a thing cannot move unless there is empty space ahead of it to move into. So the denial of the void entails the denial of motion: in a completely full reality, nothing can move, and the appearance of motion is another illusion. Here Parmenides’ abstract logic about ‘is’ and ‘is not’ reaches all the way down into physics, dictating that the world must be a single, motionless, gapless fullness. And here, too, lay the problem that would generate one of the greatest ideas in the history of science: for to rescue motion, later thinkers would have to find some way of admitting empty space - of saying, against Parmenides, that ‘nothing’ somehow is.
Parmenides’ denial of the void is a perfect illustration of how the most fruitful ideas in the history of thought often arise as responses to a powerful error. By arguing, with a rigour no one could ignore, that empty space cannot exist and therefore motion is impossible, Parmenides forced the question: what would reality have to be like for motion to be possible? And the answer the Atomists gave - atoms moving in a void - became the foundational framework of physical science for over two thousand years, the picture of reality as particles in empty space that runs from Democritus through Epicurus and Lucretius to Galileo, Newton, and the kinetic theory of matter.
The deeper lesson is about the strange productivity of rigorous philosophy. Parmenides reached false conclusions - there is a void, there is motion - but he reached them by an argument so clean that it could not simply be ignored; it had to be answered, and answering it required inventing new and powerful concepts (the void, the atom, the distinction of being and not-being). This is the pattern of his entire influence: a magnificently wrong argument that, precisely because it could not be waved away, compelled the creation of the ideas that would form the backbone of Western science and metaphysics. The denial of the void gave us the concept of the void; the denial of plurality gave us atomism; the denial of change gave us potentiality and actuality. Few philosophers who reached so many false conclusions have done so much to advance human understanding. Parmenides shows that in philosophy, as in physics, a sufficiently sharp problem is worth more than a vague truth - and that the history of thought is driven as much by brilliant errors demanding solution as by discoveries quietly accepted.
This is the opening of the lesson. The rest — the dialogue, the primary source, and the recall — is in the app.
You learned that Parmenides distinguished two ways of inquiry - the true ‘It is’ and the impossible ‘It is not’ - and denied that the void (empty space, ‘nothing’) could exist, which (since motion seems to need empty space to move into) led him to deny motion, and forced the Atomists to resurrect the void. Explain the…
Leads to Gorgias.
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