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History of Science Ancient Egypt

History of Science Online

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LibraryThing: Science in Ancient Mesopotamia Week 3: Ancient Egyptian and Aegean science

Parmenides of Elea (fl. 485 B.C.)

| Presocratics Index | Intro | Thales | Anaximandros | Anaximenes | Herakleitos | Parmenides | Zenon | Melissos |
| Atomists: Leukippos and Demokritos | Anaxagoras | Empedokles | Significance of the Presocratics |

ParmenidesParmenides founded one of the most remarkable and influential schools of early natural philosophy in the Greek colony of Elea (modern Velia), located in west-southern Italy. Elea was founded around 540 B.C. by Greeks fleeing the Persian invasion of Ionia.

Parmenides' work, On Nature, is a poem in three parts, consisting of a "Proemium," or introduction; "The Way of Truth" (aletheia); and "The Way of Opinion" (doxa). How far can one travel on the "way of truth" without giving in to the "way of opinion"?

Parmenides of Elea took the premises of monism and extended them to a logical but radical conclusion.

"The horses which bear me conducted me as far as desire may go, when they had brought me speeding along to the far-famed road of a divinity who herself bears onward through all things the man of understanding. Along this road I was borne, along this the horses, wise indeed, bore me hastening the chariot on, and maidens guided my course. The axle in its box, enkindled by the heat, uttered the sound of a pipe (for it was driven on by the rolling wheels on either side), when the maiden daughters of Helios hastened to conduct me to the light, leaving the realms of night, pushing aside with the hand the veils from their heads. There is the gate between the ways of day and night lintel above it, and stone threshold beneath, hold it in place, and high in air it is fitted with great doors; retributive Justice holds the keys that open and shut them. However, the maidens addressed her with mild words, and found means to persuade her to thrust back speedily for them the fastened bolt from the doors; and the gate swinging free made the opening wide, turning in their sockets the bronze hinges, well fastened with bolts and nails; then through this the maidens kept horses and chariot straight on the high-road. The goddess received me with kindness, and, taking my right hand in hers, she addressed me with these words: --Youth joined with drivers immortal, who hast come with the horses that bear thee, to our dwelling, hail! Since no evil fate has bid thee come on this road (for it lies far outside the beaten track of men), but right and justice. 'Tis necessary for thee to learn all things, both the abiding essence of persuasive truth, and men's opinions in which rests no true belief. But nevertheless these things also thou shalt learn, since it is necessary to judge accurately the things that rest on opinion, passing all things carefully in review." (Hanover Historical Texts Project)

In the Proemium (above), he wrote as if he had experienced a prophetic revelation from the gods, who revealed that only reason -- not sense experience -- may apprehend nature truly. Reason is the road to truth; sensory experience is the way to opinion.

In other words, the ultimate conclusion of monism is that everything is a single plenum, with no void. All is One, an indivisible plenum, and change of any kind is impossible!

If you say, "But changes seem to occur all around us!," then Parmenides would reply, "Our senses, obviously, deceive us. Let us pursue the road of truth rather than of opinion."

If you then ask: "If our senses deceive us to such a great extent, then how could we ever know anything?" Parmenides would reply: "Reason, not experience, is the one true way that nature is known!"

"CONCERNING TRUTH Come now, I will tell thee -- and do thou hear my word and heed it -- what are the only ways of enquiry that lead to knowledge? The one way, assuming that being is and that it is impossible for it not to be, is the trustworthy path, for truth attends it. The other, that not-being is and that it necessarily is, I call a wholly incredible course, since thou canst not recognise not-being (for this is impossible), nor couldst thou speak of it, for thought and being are the same thing. It makes no difference to me at what point I begin, for I shall always come back again to this. It is necessary both to say and to think that being is; for it is possible that being is, and it is impossible that not-being is; this is what I bid thee ponder. I restrain thee from this first course of investigation; and from that course also along which mortals knowing nothing wander aimlessly, since helplessness directs the roaming thought in their bosoms, and they are borne onward deaf and likewise blind, amazed, headstrong races, they who consider being and not-being as the same and not the same; and that all things follow a back-turning course. That things which are not are, shall never prevail, she said, but do thou restrain thy mind from this course of investigation." (Hanover Historical Texts Project)

Catherine Osborne summarizes the importance of Parmenides' "powerful distinction between appearance and reality.... [that] helps us to see that there might be truths that no one knows. And there may be beliefs that are universally held but actually false. It also shows that science does not proceed by observation, as one might have thought. Observation can only ever provide the untested appearance." Presocratic Philosophy, p. 50.

Historian of science G.E.R. Lloyd argues, in Magic, Reason and Experience, that in Parmenides we find the earliest examples of sustained, rigorously logical, argumentation. For example, Parmenides employed the formal logical techniques of Modus Tollens, reductio ad absurdum, and the principle of Sufficient Reason.

Parmenides applied his affirmation of monism and the principle of sufficient reason to argue for the eternity of the universe:

"And let not long-practised habit compel thee along this path, thine eye careless, thine ear and thy tongue overpowered by noise; but do thou weigh the much contested refutation of their words, which I have uttered. There is left but this single path to tell thee of: namely, that being is. And on this path there are many proofs that being is without beginning and indestructible; it is universal, existing alone, immovable and without end; nor ever was it nor will it be, since it now is, all together, one, and continuous. For what generating of it wilt thou seek out? From what did it grow, and how? I will not permit thee to say or to think that it came from not-being; for it is impossible to think or to say that not-being is. What would then have stirred it into activity that it should arise from not-being later rather than earlier? So it is necessary that being either is absolutely or is not. Nor will the force of the argument permit that anything spring from being except being itself. Therefore justice does not slacken her fetters to permit generation or destruction, but holds being firm." (Hanover Historical Texts Project)

In effect, Parmenides' argument is "how can what is, come to be from what is not?" This seems like a logical argument, but the principle of sufficient reason is added to it in the sentence that is italicized above: What would then have stirred it into activity that it should arise from not-being later rather than earlier? Imagine a timeline with points A, B and C:

Suppose that the universe had been created at time B. Why should the universe come to be at time B, rather than at time A or C? If there were a sufficient reason for it to come to be at time B, then the very same reason would have caused it to be at time A and time C, because before the creation of anything, times A, B and C were indistinguishable. Therefore, if the universe exists at any point in time, it will have existed forever and will continue to exist forever. In other words, either the universe is eternal or its cause is irrational. This argument for the eternity of the universe proved compelling to Aristotle and later natural philosophers until Augustine answered it around 400 A.D.

“It never was nor will be, since it is now, all together, one, continuous. For what birth will you seek for it? How and whence did it grow? I shall not allow you to say nor to think from not being: for it is not to be said nor thought that it is not; and what need would have driven it later rather than earlier, beginning from the nothing, to grow? Thus it must either be completely or not at all.... Therefore Justice has never loosed her fetters to allow it to come to be or to perish, but holds it fast. And the decision about these things lies in this: it is or it is not. But it has in fact been decided, as is necessary, to leave the one way unthought and nameless (for it is no true way), but that the other is and is genuine. And how could what is be in the future? How could it come to be? For if it came into being, it is not: nor is it if it is ever going to be in the future. Thus coming to be is extinguished and perishing unheard of.” (Hanover Historical Texts Project)

In any case, Parmenides wrote in verse, as befitted a prophet entrusted by the gods with this astonishingly fruitful approach to knowing nature that is reason. To refute Parmenides' conclusions it would be necessary to engage in similarly sophisticated intellectual discourse, as his followers Zenon and Melissos pressed home (next two pages). With the Eleatics, then, important questions are raised, including the void vs. plenum, sense experience vs. reason, atomism vs. continuously divisible matter, finite vs. infinite cosmos.

First principle
Thales of Miletos
Anaximandros of Miletos
Anaximenes of Miletos
Herakleitos of Ephesos

Parmenides of Elea,
Zenon of Elea,
Melissos of Samos


Monism, Plenism, Rationalism, Necessitarianism, Sufficient Reason, Akinesis, Eternity of the World


"Inconsistencies cannot both be right; but, imputed to man, they may both be true." Samuel Johnson

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HSCI 3013. History of Science to 17th centuryCreative Commons license
Kerry Magruder, Instructor, 2004
Brent Purkaple, TA

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Many thanks to the pedagogical model developed in Mythology and Folklore and other online courses by Laura Gibbs, which have been an inspiration for this course.

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