Plato claims that Parmenides visited Athens at the age of 65 c. 450 BCE, when Socrates was a young man, thus making him an older contemporary of Socrates (Plato, Parmenides, 127a-c). If Plato’s account is trustworthy, then Parmenides was born in the later part of the sixth century, c. 515-10 BCE. Diogenes Laërtius claims, however, that Parmenides flourished just before 500 BCE, which would put his year of birth earlier c. 540 BCE (Lives, 9.23). So the date of Parmenides’ birth is uncertain. Belonging to a wealthy and prominent family, Parmenides resided in Elea, a Greek city in southern Italy, which, according to Herodotus, had been founded by Ionian Greeks fleeing the Persians just before 535 BCE (1.164). For this reason, his philosophy is often referred to as Eleatic philosophy. Plato has Socrates say that he was impressed by Parmenides when he met him as a young man: "Parmenides seems to me to be, in Homer's words, 'one to be venerated' and also 'awful'. For I met him when I was very young and he was very old, and he appeared to me to possess an absolutely noble depth of mind." Two of Parmenides’ more prominent followers were Zeno of Elea and Melissus of Samos. Also Parmenides had an influence on Plato, who wrote a dialogue named Parmenides.
Parmenides wrote a poem
entitled On Nature, in which he expressed his philosophical views;
only fragments of this work have survived, quoted in the works of others.
Approximately 160 lines of Parmenides’ poem remain today; the original
text was supposed to have had 3,000 lines. Most of the fragments have
been preserved by Simplicius, who inserted them into his commentary. So
different from most of the other pre-Socratics, the historian is less
dependent on secondary sources for an understanding of Eleatic philosophy.
The poem On Nature was divided into three parts. First, it opened
with a proem (prooimion), which served as an introduction to the
entire work. Second, there was a section called “the way of truth”
(alêtheia) in which Parmenides explains the nature of reality.
Third, following “the way of truth” is a section known as
“the way of opinion” (doxa) in which Parmenides describes
how reality deceptively appears to human beings.
It is clear from his poem, On Nature, that Parmenides' philosophical method is an ancient form of what is now known as rationalism. Like all rationalists, he assumed that any proposition that was logically necessary, or self-evident, must be admitted as true. By logically necessary, or self-evident, is meant that one cannot deny the proposition without falling into logical contradiction. Any such proposition always has priority over a proposition about reality derived from sense data; no matter how at odds with the world of common sense it may be, a necessary proposition must always take precedence. Parmenides concludes that reality is the opposite of how it appears to the five senses. For him, being is one, uncreated, indestructible, unchangeable, finite and spherical. The experience of reality as the opposite of this is, for him, ultimately an illusion.
The poem On Nature by Parmenides of Elea distinguishes between two "ways," " the way of truth" (alêtheia) and "the way of opinion" (doxa). Obviously, the "way of truth" is the correct way, the correct understanding of Being, whereas the "way of opinion," the view of the majority, is illusory, although useful. In some cases, it is necessary to fill in some gaps in Parmenides' arguments. What makes the "way of opinion" illusory is the fact that its proponents naively accept the testimony of their senses, rejecting reason (logos); in other words, they assume wrongly that being is as it appears to be. The most basic, necessary or self-evident truth from which Parmenides deduces other, corollary truths is that "It is" (estin). This is true necessarily or self-evidently, so that one cannot deny it without falling into logical contradiction. What he means by "It is" is that "What is, is," which is an application of the what philosophers call the principle of identity: something is what it is, or A » A (if you have A, then you have A). It seems that he has made Being or existence into a predicate, so that "It is" means Being is real, from which it follows that Being cannot not be real at the same time, being the application of the principle of identity: What is, is and therefore What is, cannot be anything other than what it is. Parmenides says, "Come now, I will tell you—and 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 it not to be, is the way of belief, for truth is its companion" (4, 5). According to Parmenides, as contrary to the world of common sense as this may be, insofar as what is, is, it is impossible for it not to be. What is, therefore, is necessary: it cannot not be.
To provide further evidence for his position, Parmenides explains, "The other, namely, that It is not, and that it must not be,—that, I tell you, is a path that none can learn of at all. For you cannot know what is not—that is impossible—nor utter it" (4, 5). His point is that one cannot conceive of what is not, from which it follows nothing cannot be: it is impossible to hold that something is not or that nothing is. Only what can be conceived can be. He then adds what apparently he considers another necessary or self-evident truth: "For it is the same thing that can be thought and that can be" (4, 5). In other words, he espouses the rationalist dictum that thought and Being are identical. He might say in defense of this view that what is thought must be, for otherwise one would be thinking about nothing, which is impossible. In summary, since one can think about Being ("It is"), it follows that Being must be, and, if it is, it cannot not be. Conversely, since it cannot be thought of, nothing cannot exist.
Parmenides continues, "It must be that what can be thought and spoken of is; for it is possible for it to be, and it is not possible for what is nothing to be" (6). Parmenides asserts that what can be thought must be insofar as it can be thought; the objects of thought exist as thought. What is excluded by this is the possibility of thinking and speaking of objects that are usually considered not to exist, such as unicorns or cyclops; to think and speak of about such objects of the imagination, contrary to popular opinion, implies their existence as thought. Later in the poem he reaffirms this position, "The thing that can be thought and that for the sake of which the thought exists is the same; for you cannot find thought without something that is, as to which it is uttered" (8). Thinking cannot think about nothing, since thinking must have an object; this means that thought must be of something, even if it does not exist as perceptible by the senses, but is only imaginary. Although he does not say so explicitly, one could say that Parmenides attributes existence primarily to objects of thought, as opposed to objects of sense: something is insofar as it is thought. This would commit him to some form of idealism: the primacy of spirit or mind over the material, that the cosmos is primarily thought. Parmenides then adds, "For this shall never be proved, that the things that are not are; and do restrain your thought from this way of inquiry" (7). Again he asserts that is is a contradiction to affirm that something that is not, is; one cannot think about or speak about what is not as if it existed.
Knowing the truth that "what is, is" and "what is not, cannot be," Parmenides rebukes the ignorant masses, "Undiscerning crowds, in whose eyes it is, and is not, the same and not the same, all things travel in opposite directions" (6). The unreflective person, relying upon the testimony of his senses, affirms that something is and is not; in other words, something comes into being and then perishes. The same person will also say that a thing is the same and not the same: insofar as it changes, something is not the same as it was before it changed, but insofar as in every change something remains the same (the substratum), the thing that changes is the same. He concludes, "One path only is left for us to speak of, namely, that It is." (8) In his view, Being is what it is and cannot change in the sense of becoming what it is.
In the next section of On Nature, Parmenides draws out implications for his conclusion that what is, is and what is not, cannot be. He says:
If it is, then what is (or Being) has always been what it is and will not cease being what it is. In other words, what is did not become what it is, but has always been that, nor will it cease to be. This is what he means when he says that what is "is uncreated and indestructible...and without end." The implication of what he is saying is that generation in time is ultimately unreal: "Nor was it ever, nor will it be; for now it is, all at once, a continuous one." The reason that Parmenides holds this view is that to say otherwise is to affirm that something comes from nothing, which is nonsensical since nothing comes from nothing. In his view, only two alternatives are given: it is or it not. He states, "Therefore must it either be altogether or be not at all." But the latter statement is contradictory, which leaves only the former statement as true: "Surely it is adjudged, as it must be, that we are to set aside the one way as unthinkable and nameless (for it is no true way)." For him, generation is impossible since this requires that something not be either in the past or the present: "If it came into being, it is not; nor is it if it is going to be in the future." Something cannot be said to be now but not in the past or not be now but to be in the future, because that would mean that something (the subject) was not but is now or is not yet but will be, which is a contradiction, since it is said both to be and not to be at the same time. Aristotle further explains the rationale behind Parmenides' view as follows: "First, if it comes into being from something, then it does not come into being at all, since it already exists; second, if it comes into being from nothing, then it cannot come into being, since something cannot come from nothing” (Physics 187a 34). Parmenides adds that something cannot come from nothing because, there could be no reason found for why something would come from nothing at one time and not another: "And, if it came from nothing, what need could have made it arise later rather than sooner?" In addition, he holds that something cannot cease to exist: "Thus is becoming extinguished and passing away not to be heard of." Something cannot cease to exist because then nothing would become a predicate of a subject, which is nonsensical, since nothing is not something. It follows that, if generation and destruction are impossible, then what is (or Being) is eternally the same, unchanging. This Parmenides expresses by saying that what is (or Being), "is complete, immovable." It is immovable because generation and destruction are impossible and it is complete because it already is what it is. He concludes, " Wherefore, Justice does not loose her fetters and let anything come into being or pass away, but holds it fast."
Parmenides also concludes that what is (or Being) is indivisible: "Nor is it divisible, since it is all alike, and there is no more of it in one place than in another, to hinder it from holding together, nor less of it, but everything is full of what is. Wherefore it is wholly continuous; for what is, is in contact with what is" (8). Divisibility means the separation of what is from itself. What is (or Being) could not divide itself from itself, however, since it is uniform and continuous. Although he does not say so explicitly, it seems that he holds that what is (or Being) is indivisible because nothing could separate it from itself, since nothing cannot be something by which to produce this effect.
Parmenides says further that what is (or Being) is not infinite, in the sense of being unformed or unfinished. Rather, "It is immovable in the bonds of mighty chains, without beginning and without end." For what is to be "immovable in the bonds of mighty chains" makes it finite, since, if it were infinite, it would not be something, but be incomplete and therefore have a lack or nothingness in its being, which is a contradiction. To have such a lack would mean that it is in part nothing, but nothing cannot be for reasons already explained. In fact, he concludes that what is (or Being) is a sphere. He writes:
Since, then, it has a furthest limit, it is complete on every side, like the mass of a rounded sphere, equally poised from the center in every direction; for it cannot be greater or smaller in one place than in another. For there is no nothing that could keep it from reaching out equally, nor can anything that is be more here and less there than what is, since it is all inviolable. For the point from which it is equal in every direction tends equally to the limits. (8)
As finite, what is (or Being), is complete or finished on every side; since he concludes earlier that what is, is uniform—"cannot be greater or smaller in one place rather than another"—Parmenides decides that what is (or Being) is spherical: a sphere is equal and identical in every direction from its center until it reaches its limits, the circumference of the sphere. His view is that what is (or Being) must be the geometrical shape that is most simple (incomposite) and uniform; if nothing cannot be, then what is (or Being) can only be a sphere. Apparently, Parmenides cannot conceive of what is (or Being) as anything but physical, and so as having a three-dimensional shape.
The fragments of the section part of On Nature, "The Way of Opinion," are less numerous than the first part. It is not difficult to figure out, however, what characterizes the second way: human beings err, when relying upon their senses; they conclude that what is (or Being) is plural, differentiated and becoming. Thus, he writes:
Mortals have made up their minds to name two forms, one of which they should not name, and that is where they go astray from the truth. They have distinguished them as opposite in form, and have assigned to them marks distinct from one another. To the one they allot the fire of heaven, gentle, very light, in every direction the same as itself, but not the same as the other. The other is just the opposite to it, dark night, a compact and heavy body. Of these I tell you the whole arrangement as it seems likely; for so no thought of mortals will ever outstrip you. (8)
Parmenides criticizes those philosophers who posit two ultimate, opposite "forms" or principles by which all things become what they are: light and darkness, light and heavy (or any other pair of opposing principles). It is wrong to think that things came into being through the interaction of these two opposing principles. This implies that one should not differentiate what is (or Being) from itself. In the quotation above, he says that one should not actually name one of the principles. His point seems to be that one of a pair of opposites is really only the negation of the other, and so does not and should not have a name since what is not is impossible (e.g. light and not-light, i.e. darkness). It is equally erroneous to name the things that supposedly came into existence through the interaction of pairs of opposites, as if they actually existed: "Thus, according to men's opinions, did things come into being, and thus they are now. In time they will grow up and pass away. To each of these things men have assigned a fixed name" (19). What appears to come into being from the interaction of opposite principles does not really do so. In spite of his pronouncement that it is fundamentally at odds with the truth, Parmenides does, however, seem to allow for a study of "opinion." He does not dismiss appearance as completely worthless delusion to be ignored and despised. Rather, he advises that a person know the phenomenal world, the world of sensible appearance: "You must learn all things, as well unshakable heart of well-rounded truth as the opinions of mortals in which there is no sure trust" (as quoted by Diogenes Laertius, Lives, 9.22). This implies that Parmenides worked with the notion of two "truths," an ultimate and a non-ultimate truth. Although it is illusion, the latter is still worth knowing for practical reasons.
There are a few accounts of Parmenides' philosophy in the works of others; these agree with what is found in his poem, On Nature.
2.1. Plato writes:
Plato's statement that "the all is alone, unmoved" refers to the fact that, according to Parmenides, what is (or Being) is one and eternally the same, and not subject to becoming. In addition, anything in the phenomenal world that can be differentiated from its source and from other things and so be named ultimately is the one thing, which is what Plato means by the statement "to this all names apply." Plato also identifies as belonging to Parmenides (and Melissos) the view that one has no empty space, which is required for locomotion.
2.2. Aristotle explains that, although he affirmed that one thing exists, Parmenides still formulated theories to account for observed facts:
For, claiming that, besides the existent, nothing non-existent exists, he [Parmenides] thinks that of necessity one thing exists, viz. Being (to on) and nothing else (on this we have spoken more clearly in our work on nature), but being forced to follow the observed facts, and supposing the existence of that which is one in definition, but more than one according to our sensations, he now posits two causes and two principles, calling them hot and cold, i.e. fire and earth; and of these he ranges the hot with the existent, and the other with the non-existent. (Metaphysics, 1.5; 986b 28-987a 2)
Aristotle says that for Parmenides ultimately only one thing exists, which he calls being (to on), even though he allows for non-ultimate explanation by appealing to two opposing principles (called hot or existent and cold or non-existent), so long as one recognizes that what one knows is merely opinion.
2.3. Theophrastus summarizes Parmenides' view of "twofold truth":
And succeeding him Parmenides, son of Pyres, the Eleatic—Theophrastos adds the name of Xenophanes—followed both ways. For in declaring that the all is eternal, and in attempting to explain the genesis of things, he expresses different opinions according to the two standpoints: from the standpoint of truth he supposes the all to be one and not generated and spheroidal in form, while from the standpoint of popular opinion, in order to explain generation of phenomena, he uses two first principles, fire and earth, the one as matter, the other as cause and agent. (Theophrastos, Fr. 6 ; Alexander Metaph. p. 24, 5 Bon.; Dox. 482)
Theophrastus indicates that Parmenides had two types of explanation: truthful and popular opinion. According to the former, nothing is created or destroyed but all is one, eternal and spherical. According to the latter, things are generated and destroyed by means of the interaction of two opposing principles: earth or passive matter and fire as agent.