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Publication: The Review of Metaphysics
Date published:
Language: English
PMID: 28386
ISSN: 00346632
Journal code: PRMP

THE QUESTIONS RAISED by the great pre-Socratic philosopher Parmenides were perhaps the main challenge for Plato and Aristotle, two of the greatest post-Socratic philosophers. To summarize the challenge briefly: Parmenides denied that there was any change in the world. Although the average person has intuitions from sense experience that run contrary to this claim, Parmenides had a logically valid argument that proved his theory. Parmenides denounced the intuitions of sense experience as falsities, the way of opinion. The way of truth was to accept his theory, that there is no change, all being is one, and the multiplicity of individual beings is a mere illusion.

Parmenides' line of argument is as follows. Change is coming into being. If something comes into being, it comes into being from something that existed before. What was it before? There are only two possibilities, which make up the Parmenides problem:

either : 1. Being comes from being.

or. 2. Being comes from nonbeing.

If #1 is correct and being comes from being, in that case the same thing exists before and after, and no change occurs. If #2 is correct and being comes from nonbeing, in that case nothing comes to be. Nothing comes from nothing after all, so no change occurs. The conclusion is that there is no such thing as nonbeing, and no such thing as change. The world is all one being, and there is no division into separate individual beings that interact and change.

If Parmenides' argument seems tricky, it ought to. It has seemed tricky to all thinkers who have followed Parmenides. There were even a few unscrupulous thinkers who took advantage of this trickiness and used it as a justification for moral relativism. These thinkers were the sophists, and the most brilliant of them was Protagoras. Protagoras claimed that each individual man was "the measure of all things," so the same thing that was good for one man might not be good for another based on perspective.1 Ultimately, Protagoras claimed there was no measure of goodness based on human nature because human nature as a separate individual form did not exist. Only being exists, as Parmenides argued; Protagoras said the rest of what we take to be reality is an illusion and subjective. Protagoras' argument is a stronger version of the sophist arguments about convention and nature (nomos and phusis). As Plato and Aristotle both recognized, the Parmenides problem had implications for politics as well as for philosophy.

No philosopher was able to accurately interpret and refute the Parmenides problem until Plato and Aristotle. Plato answered it in an important way in his dialogue the Sophist, and Aristotle followed this up with the complete answer in Physics book 1, chapter 8. My thesis is that Plato's answer would have been good enough to defeat Protagoras in extended argument, thereby remedying the political aspects of the Parmenides problem. However, Aristotle's answer is required to answer some additional philosophical and scientific aspects.

The first section of this paper will summarize the history of preSocratic philosophy and explain why Parmenides was a turning-point. The second section will explain the sophist Protagoras' relation to the Parmenides problem. The third part will present Aristotle's complete answer to the Parmenides problem, and in the fourth part I will compare that approach with Plato's solution in the Sophist. Lastly, I will sum up by characterizing how I think Plato and Aristotle would have responded to Protagoras' Parmenidean sophistry in political life.


From what we know about early pre-Socratic thought, the speculations of the philosophers did not clash against the intuitions of the average man as they did after Parmenides and the sophists. The typical pattern of the school of Miletus was to propose an underlying element that could explain the world that philosophers experienced around them. Tha´es proposed water, Aniximander proposed "the indefinite," and Anaximenes proposed air. Each had arguments for their principle element, and development occurred as new hypotheses were debated. These scientific debates did not have much notable impact on the ethics, politics, or theory of knowledge of the average man, other than perhaps some influence on theology. The second major school of philosophy, the Pythagoreans, took a different tack when they proposed that abstract numbers were the ordering principles of everything, as opposed to a physical element. They made serious contributions to the Greek body of knowledge through discoveries in mathematics, music, and astronomy, and in this way had an impact on the advancement of Greek technology. However, the Pythagoreans' ideas about life and ascetic rituals were somewhat disconnected from their mathematical theories, so they did not cause too great of a disturbance for the views of the average Greek either.

Greek philosophy entered a quite different stage during the time of Heraclitus and Parmenides. These thinkers began the first serious discussions about "being," incorporating the physical elements of the Miletians and the formal/abstract elements of the Pythagoreans. Heraclitus argued that everything is in flux, at war, and changing. Only the divine principle of "logos" keeps everything in nature together in harmony. Parmenides can be thought of as a near polar opposite of Heraclitus. Instead of thinking of everything as motion and "becoming," Parmenides claimed that everything is stationary and that all is "being." As was previously mentioned in the introduction of this paper, Parmenides' proof denying nonbeing and change made his claims appear irrefutable. A clash between common sense and the theories of the philosophers developed as a result of Parmenides' work. As Plato's Stranger says in the Sophist, the "Eleatic tribe" of philosophers "look down upon us the many and despise us to excess, for they don't care whether we're following them as they speak or we fall behind, but they severally get on with their own thing."2 That is a good way to describe the natural philosophers after Parmenides and before Plato.

The generation of philosophers after the introduction of the Parmenides problem was forced to accept it or find some way to bypass it. Zeno, one of the followers of Parmenides, came up with dialectical arguments to further back up his claims about the oneness of all being. In Zeno's proofs, he would agree with the opposition's claim and then use a reductio ad absurdam argument to show how that claim was flawed. ' One strategy for dealing with the Parmenides problem, taken by Anaxagoras, was to accept the seemingly absurd premise that there are an infinite number of basically different elements. Another philosopher, Empedocles, proposed four elements that would maintain the characteristics of Parmenides' one "being," while the compounds and separations of those elements would constitute the world of appearances and plurality.4 Diogenes accepted Empedocles' four elements, but claimed those elements and everything else is made up of one unchanging being, again agreeing with Parmenides.5 These natural philosophers tried many different ways to deal with the Parmenides problem and retain the world of common sense, but the theories did not quite work.

One other school of philosophy that was created in response to the Parmenides problem lived on in different ways after the problem was solved. It was called atomism, and included thinkers like Leucippus and Democritus. The atomists claimed that all bodies are made up of an infinite number of tiny, indestructible particles. The beings we see are in fact aggregates of these atoms. This is why human beings think change can exist; they see different arrangements of atoms. However, the atomists argued that no change can ever happen to the atoms themselves. In this way they were able to agree with Parmenides while still explaining the phenomenon of motion. The atomists' theory was not wholly satisfactory in explaining what keeps the atoms bonded together, but it was sufficiently convincing to be maintained in Hellenistic times by the Epicureans, and was later revived (after a fashion) in modern science. A satisfactory answer to the Parmenides problem was developed in the meantime, so it could be said that the theory outlived the initial question that brought it into existence.

None of the authors discussed in this section solved the Parmenides problem. The next section will discuss one last group of ancient thinkers who did not have a solution to the problem, but an original interpretation of it: Protagoras and the sophists.


Parmenides' argument bore political fruit when his theory was adopted by Protagoras, an unscrupulous teacher of law and persuasion. Protagoras reacted to the Parmenides problem in a different way than the natural philosophers did. Instead of seeing it as a problem, he saw it as an opportunity for gain. Protagoras taught justifications for relativism, which his students used to write off evidence in court and often to defend bad actions.

In Plato's Sophist, one of the appellations the sophists receive is the title of "contradictors," and the "teachers of contradiction."6 Specifically in private associations, the sophists were very skilled at contradicting general statements "about being and becoming."' With regard to law and political things, the sophists applied contradiction to "all arts" and "each craftsman," telling them how to do their jobs.8 In Plato's Meno, Socrates says that "for more than forty years all Greece failed to notice that Protagoras was corrupting his classes and sending his pupils away in a worse state than when he took charge of them."9 Aristotle paints an equally negative picture of Protagoras in his Rhetoric: "(making the weaker argument the stronger] is why human beings were justly disgusted at Protagoras's pronouncement. For it is false, and not a true but an apparent likelihood, and not present in any art other than rhetoric and debating."10 Plato and Aristotle contended that the misleading of others through "apparent likelihoods" was also at play in the Parmenides problem, a basis for Protagoras' relativism."

Since Parmenides' claim that the world of sense-perceived objects belongs to the realm of illusion could not be refuted, judgments made by individuals upon those sense-perceptions were lowered to the status of opinions as opposed to facts. In other words, things are as they seem to me. According to Aristotle, "[Protagoras] said that a human being is the measure of all things, meaning nothing else than that what seems so to each person is solidly so."12 Things may seem different to you, but there is no way to judge who is right. This kind of sophistry brings all evidence into question, allowing Protagoras to "make the weaker argument the stronger." Protagoras' argument also brings the concept of human nature itself into question: "It is necessary for them [the Protagoreans] to say that all things are incidental, and that there is not anything which is the very thing it is to be human or to be an animal."" Different people's contradictory claims will lead to some bizarre conclusions: "the same thing would be a battleship and a wall and a human being, if something admits of being affirmed or denied of everything, as it must for those who repeat the saving of Protagoras."14

In tracking down Protagoras' trickery, Aristotle suggests that it can be resolved "by those who examine its source." There are two sources that Aristotle names. The first is the legitimate, common sense intuition that "not all people discern the same things about the same things, but this thing seems sweet to some people and the opposite to others."15 Protagoras, however made it seem as though things that were not matters of taste were matters of taste. The second source of Protagoras' trickery is theoretical: "it seems to have come about for some people from the opinion of those who study nature,"16 that is, the natural philosophers, Heraclitus, and Parmenides. Knowing that the natural philosophers had been stymied by the Parmenides problem,17 Protagoras was free to weave his lies, and dismantle arguments that might appeal to an objective standard of truth. Both sources of Protagoras' relativism needed to be dealt with for philosophy and science to regain their rightful epistemological statuses.

Plato and Aristotle both have extended arguments against Protagoras, as well as shorter answers. The extended arguments against Protagoras involve a refutation of Parmenides' theory, but the shorter answers focus on the common sense and perception of the average man. Plato's Theatetus offers a set of short answers to Protagoras in the context of the question of whether all knowledge is sense-perception. Sense-perception is tied to the question of being and nonbeing and Heraclitus' contention that everything is in motion. Plato's Socrates argues that "if all things are in motion- every answer, about whatever one answers is similarly correct. Or if you want . . . every answer becomes correct."18 This argument works well with Protagoras' relativistic statement that each man is the measure of all things. Classics scholar Richard McKirahan summarized the short answers offered in the Theatetus against Protagoras in this way:

Perceptual and ethical judgments apart, how plausible is relativism? If I think 2+2=5, does that make it true? If I think I can survive a fall from the roof of the Parthenon, does that guarantee I will? If I think Protagorean relativism is false, does that make it false?19

Plato's contention in the Theatetus was that not all opinions are equally true, and not all judgments are equally good. Plato makes a similar argument in the Sophist when the Stranger says that we "share in becoming through perception"; sense-perception itself is a certain motion in the mind necessary for the intake of knowledge."0 The Stranger's advice to those who love wisdom is to "refuse to accept the all as stationary," since observing motion is an important way of gaining knowledge.

Aristotle repeats Plato's short answers to Protagoras several places, particularly in the Metaphysics. In one of the more flippant and humorous passages Aristotle ever wrote, he explains why Protagoras is wrong on the level of common sense:

But if everyone alike is both in the wrong and speaks the truth, it will not be possible for a person to utter or say anything; for at the same time he says both these things and not these things. . . . And from this most of all it is most obvious that no one is in this condition, neither anyone else nor those stating this argument. . . . And why does he not march straight into a well in the morning, or straight off a cliff, if it happens that way, but why does he take care, as though not believing that falling was both good and not good? Therefore it is clear that he does conceive of one thing as better and the other as not better. . . . For one who has an opinion, as compared with the one who has knowledge, is not disposed in a healthy way toward truth.22

These short answers to Protagoras by Plato and Aristotle would work well in a debate, but in extended argument Protagoras might still appeal to the Parmem'des problem. Plato's Socrates demurred from taking up the Parmenides problem in the Theatetus, even though his interlocutors asked to have it answered. Socrates' reason was that "the speech we now awaken makes it impossible to handle by its immensity."21 Plato's response to Parmenides as found in the Sophist, and Aristotle's response as found in the Physics, will be discussed in the next two sections.


Aristotle's answer to the Parmenides problem can be found in Physics, book 1, chapter 8. Aristotle takes the common opinion that change is real as the starting point for an extended philosophical argument against Parmenides. Philosophers had doubted their common sense intuitions because of Parmenides' theory. Aristotle's argument is that the premises of Parmenides' theory were true in one sense, but false in another sense.

The key to Aristotle's argument is the distinction between per accidens truths and per se truths. Something is a per se truth if it is true through itself, almost like a definition. It is per se true that "a golfer golfs." It may also be true that "a teacher golfs," but that is only true per accidens. Nothing about being a teacher per se implies that he would be a golfer. The example used by Aristotle is that of a doctor who might build a house. As Aristotle says, "the doctor (iatros} builds a house not as a doctor but as a housebuilder . . . but he heals (iatreue´) or becomes a failure at healing as a doctor."24

Aristotle keeps the per se/per accidens distinction in mind when looking at the two possibilities of the Parmenides problem, that:

either. 1. Being comes from being.

or: 2. Being comes from nonbeing. ,

Aristotle argues that #1 and #2 are both per accidens truths, but neither is a per se truth.25 In a per accidens way, animals are born from other animals, and "being comes from being." In another per accidens way, new animals come into existence that did not exist before, and "being comes from non-being."┐e Parmenides had treated each premise as if it were per se true, and that is how he moved to his absurd conclusion that no coming into being occurs. The Parmenides prob-lem is therefore a game played with per accidens truths pretending to be per se truths.

Aristotle proposes a different per se truth about change that encompasses the examples in a way that Parmenides' formulations cannot. The per se truth is that:

3. Potential being becomes actual being.27

The truth is that a golfer can golf, he has the potency to do so, just as a rational animal can reason. Some golfers may not actualize their potency at a given time, but they have the potency to golf because of what they are. Potencies may also conflict, for instance, if I wanted to golf instead of teaching today. What is important is that the number of potencies that I can fulfill is radically limited by what I am. As the Eleatic Stranger says in the Sophist, Theatetus cannot become a flying thing.28 Today, we could perhaps put Theatetus on a plane and he would fly, but he would only be flying in a per occidens sense; it would not be due to the fact that Theatetus is a human being. Being a certain kind of thing gives you a package of per se potencies which you can then actualize. Animals come from other animals because animals have a potency to produce offspring, which may or may not be actualized. In order for change to be real, there must be a plurality of beings before and after change,29 although an infinite number is not necessary.

Individual beings have potencies because they are composites of form and matter. Parmenides' two premises focus either on the form alone or the matter alone, and therefore end up as per se false. With #1, "being comes from being," we tend to think of the forms which are reproduced in a new being from parents who look the same. With #2, "being comes from non-being," we tend to think of the new matter that makes up the being, which we did not see before the change. However, change is not attributed to form or matter as such, but to composite beings made up of both. Composite beings have potencies that are not completely actualized, and can lead to generation or corruption. This shows in what way "a thing that comes to be comes from what is not and in what way [a thing comes to be] from what is."30 Consequently, what Aristotle calls "the very thing which is" must be pure actuality, admitting of no change.

Another misleading aspect of the Parmenides problem has to do with the ambiguity of the term "being." As Aristotle says in Physics, book 1, chapter 3, "he [Parmenides] takes being to be meant simply when it is meant in more than one way."31 We are made to think of an individual being or animal when the Parmenides problem is posed. However, when Parmenides spells out the consequences of the argument, he refers to "being" as both "one thing" and "the very thing which is and is one."32 It is not valid for Parmenides to switch back and forth by treating the two as the same/13 Aristotle holds that being refers both to "one thing" and to "the very thing which is," and shows that Parmenides simply could not do the same given his argument. This is yet another strike against Parmenides for those who believe in common sense. Aristotle says, "For who understands being itself other than as being some very thing that is? But if this is so, still nothing prevents things from being many, as was said."14

In the context of Aristotle's discussion in the Physics, these arguments against Parmenides are important for explaining what motion is. Aristotle says that motion is an incomplete actualization, which is only completely actualized when the object comes to a rest. To give an example, a book that is dropped has the potency to fall until it hits the floor. Solving the Parmenides problem and formulating the concept of potency contributed to perhaps Aristotle's greatest scientific discovery: a definition of motion. Aristotle's precise definition of motion is in Physics book 3, chapter 1: "The being-atwork-staying-itself of whatever is potentially, just as such, is motion."35

In a broader context, Aristotle's argument that change is real is important because he believes all forms are known through the senses.* Aristotle could just as well have disproved the Parmenides problem on a case by case basis by pointing to change in the real world around him. If Parmenides were right, he could not even know it, since his claims would not be able to escape the way of opinion. We would not be able to know if we ourselves were real or unreal. Thankfully, Parmenides was wrong, and Aristotle provided a per se true basis to explain change, being, and nonbeing.

There is an upshot from Aristotle's argument that should make us reconsider some of the things Plato said in his various dialogues. It follows from Aristotle's argument that individual men are truly real, as is the form of humanity. By contrast, in the Republic Plato stresses that the form of humanity is more real than individual humans. Both Aristotle and Plato stress that the form of humanity is real, which answers Protagoras' moral relativism, but in the Republic Plato describes individual humans as if they were known only through Parmenides' way of mortal opinion. However, Plato did not rely on such notions for his account of change in his dialogue the Sophist, which I will now discuss.


The majority of Plato's Sophist is a discussion between Theatetus and the Stranger from Elea, who, we are told, was a "comrade of the circle of Parmenides and Zeno, and a man very much a philosopher."37 Socrates asks the Stranger if he has come to "look us over and refute us,"38 but instead the Stranger ends up refuting his own teacher, Parmenides. The Stranger is asked by Socrates to discuss with Theatetus three different topics: the sophist, the statesman, and the philosopher. The Stranger says this inquiry will require "a very lengthy speech,""' and chooses first to discuss the sophist. The sophist, as it turns out in the course of the analysis, is a "fugitive into the darkness of 'that which is not.'"40

The Stranger first touches on the Parmenides problem in arguing that when the sophists say "false things in their being are," it is easy to get tangled in the contradiction of saying "that which is not is."41 The Stranger tells us that Parmenides had instructed him "on every occasion both in prose and meter" never to say that nonbeing is. However, the Stranger suspects that Parmenides himself knew that nonbeing does exist in some sense; rejecting his teaching, the Stranger says that "if it should be put to a fair degree of torture, [it] would as certain as anything make its own confession."42 Nonbeing has a tendency to hide or be "woven in with 'that which is.'"41 In a strict sense, nonbeing does not exist "alone by itself,"44 but is mixed into other things, such as images and false opinions.4" To say that nonbeing exists by itself would be to "talk as if it were one,"46 and assign it number - which the Stranger tells us we should "not even try" to do.47 On the other hand, if nonbeing is not mixed with opinion and speech, then "it is necessary that all things be true,"48 which was the contention of the relativist Protagoras. The main aspect that Plato observes in his diagnosis of the Parmenides problem is the confusion caused by the parasitical relationship of nonbeing to being.

Plato's explanation of nonbeing is that it exists in what Aristotle would later call a per accidens way. As was said in the Aristotle section of this paper, a being has a limited number ?? per se true things that can be said of it, but an unlimited number of per accidens true things, such as "Theatetus flies." In the Stranger's words, "'that which is' is extensive, but 'that which is not' is infinite in multitude."49 The Stranger defines nonbeing as the following: "one genus of everything else, scattered and distributed across 'all the things which are.'"(TM) Plato uses a special term for all of these accidental connections: "the other." The Stranger explains that "whenever we say 'that which is not,' we're not saying, it seems, something contrary to 'that which is,' but only other."61 The sophist, like Parmenides, claims that nonbeing "in no way participates in being,"52 but that is simply not true. The Stranger proves his teacher Parmenides wrong by showing that "the nature of the other both is and has been chopped into bits to extend over 'all the things that are' in their mutual relations."" False speeches involve nonbeing inasmuch as they affirm a connection that is not the case, and yet, both the predicate and the subject really exist; as the Stranger says, the sophist's false speeches are always "of something."54 This is the main refutation of the Parmenides problem that Plato makes in the Sophist.

In some of the most difficult passages of the dialogue, Plato argues against the Parmenides problem's ambiguous usage of the term "being." At Sophist 244b, the Stranger asks: "Mustn't we inquire to the best of our ability of those who speak of the all as one[;j whatever do they mean by 'that which is'?" The difference between individual beings and being itself is collapsed in Parmenides's scheme into one spherical "whole." However, any spherical whole must have a "middle and extremes,"55 and therefore parts. This contradicts Parmenides' contention that the one whole is "completely without parts."56 Instead of this arrangement, the Stranger suggests that both individual beings and being itself exists without any additional Parmenidean "whole." The Stranger proposes that a new kind of science should investigate these matters. It would proceed "through speeches" to discover "which of the genera are constant with which and which don't receive one another," and "whether there are some that hold them together through all of them."" The subject matter of this "science of the free" would be the senses "being."58

Plato comes close to making Aristotle's potency argument at the end of the Sophist. The Stranger says, "every power [dunamin], whichever became a cause for the things which previously were not to become subsequently, was a making."(TM) In this passage Plato limits the per se truth of the potency argument only to the per accidens case of "being comes from non-being," while for Aristotle potency also incorporates the per accidens case of "being comes from being." Plato's conception is also different because the Stranger goes on to say that the potency would be actualized by "a divine art," a principle outside of the being itself.60 This point highlights one of the major differences between Plato and Aristotle: Plato argues that there is participation in being in the Sophist, while participation is a concept foreign to Aristotle's teachings. In two different passages, the Stranger argues that both motion and "the other" participate in "that which is."''1 This participation is an important difference between Plato and Aristotle, and perhaps is the reason for their different ways of handling the Parmenides problem.

Plato's refutation of the Parmenides problem in the Sophist focuses on the question of how nonbeing exists. So, when looking at the problem,

either. 1. Being comes from being.

or: 2. Being comes from nonbeing.

Plato argues that Parmenides is wrong to reject #2 outright. In spite of Parmenides' contention that nothing comes from nothing and nonbeing is nothing, nonbeing in fact does exist in a per accidens sense. Aristotle picks up on Plato's argument when he talks about the "impasse of an ancient sort," that:

all beings would be one thing, being itself, unless one went to battle with and refuted the claim of Parmenides, that "never will it be brought under the yoke, that things that are not are," and that it was necessary to show that nonbeing is, for in that way, if things are many, beings would come from the one and something else.62

This is precisely what Plato does in the Sophist. In addition, Plato makes the same point in the Sophist that Aristotle makes in Physics book 1, chapter 9, namely, that Parmenides switches between the senses of "being" when spelling out the consequences of his argument. Although Plato does not lay down the complete per se truth about change that Aristotle does using the concept of potency, Plato's Sophist shows that he can at the very least refute the Parmenides problem.


In the preceding three sections, I discussed Aristotle's and Plato's answers to the Parmenides problem. In section II, I discussed their short answers that appealed to the common sense and perception of the average man. In sections III and IV, I discussed their extended arguments that involved a solution to the Parmenides problem, which prove that change is real through a proper understanding of being and nonbeing. There was even another longer and more complicated way of answering Parmenides that involved distinguishing the senses of the term "being.""'' Some interesting questions remain: how would Plato and Aristotle have responded to Protagoras' sophistic use of the Parmenides problem, if they came across it in political life? Which arguments would they have presented before the people of Athens?

I think it likely that both Aristotle and Plato would have presented the short proofs that appeal to common sense. Rhetoric, the art of persuasion, relies on making connections with shared terms. Sense experience is an ultimate shared term that everyone can understand. Perhaps it would have been necessary for Aristotle or Plato to publicly present the extended arguments about being and nonbeing once or twice during their lifetimes, just often enough that the public would remember that Parmenides' denial of change had been decisively refuted. I doubt that Aristotle and Plato would ever have presented their teachings on the senses of "being" in a public debate, since the concepts involved in those proofs are too complicated.

In Plato's Theatetus, Socrates imagines an argument with Protagoras and uses the short proofs appealing to common sense and perception.'"4 I would argue that Aristotle would have used similar short proofs based on what he says in his Sophistical Refutations. Sophistical refutations are defined as "arguments which appear to be refutations but are really fallacies, not refutations."'" Certainly Parmenides' proof that change does not exist and Protagoras' argument in favor of relativism are sophistical refutations. Aristotle discusses the Parmenides case explicitly in Chapter 33:

For an argument must be called identical when it depends on the same principle, but the same argument might be held by some people to depend on diction, by others on accident and by others on something else, because each, when applied in different contexts, is not equally clear. So, just as [of] fallacies due to equivocation, which are generally regarded as the stupidest form of fallacy, some are obvious even to ordinary minds (for almost all the most laughable remarks depend upon diction). . . . And so with almost all the rest of the ambiguities, but some even the most expert seem to fail to discern. A proof of this is that people often dispute about the terms used, for example, whether "Being" and "Unity" always mean the same thing or some thing different; for some people hold that "Being" and "Unity" are identical in meaning, while others solve the argument of Zeno and Parmenides by saying that "Unity" and "Being" are used in several senses. Similarly, too, of the arguments which are dependent on some accident and each of the other classes, some will be easier to detect and others more difficult, and it is not always equally easy to grasp into which class they fall and whether refutation takes place or not.66

Aristotle mentions the "different senses of 'being'" argument against Parmenides among the proofs that are often disputed and not obvious to ordinary minds. He cautions that even the most expert minds sometimes fail to discern this argument. Aristotle then mentions "the arguments which are dependent on some accident and each of the other classes." The per accidens truths that "being comes from being" and "being comes from nonbeing" come to mind as examples of arguments that many would find difficult to follow.0' These difficulties are the reasons why I conjecture that Aristotle would have averred from debating the sophists using the extended arguments, and would have used the short answers.

Regardless of the difficulty of the arguments involved, the fact remains that sophistical refutations must be refuted in order for the false to be rejected and for truth to prevail. Plato and Aristotle did a monumental service to philosophy by resolving the Parmenides problem.

Claremont Graduate University

1 See Joe Sachs' footnote 10 on page 214 in his translation of Aristotle's Metaphysics (Santa Fe, NM: Green Lion Press, 2002).

2 Plato, Sophist, trans. Seth Bernadette (Chicago: University of Chicago Press, 1986), 243b. Also see Aristotle, Aristotle's Metaphysics, trans. Joe Sachs (Santa Fe, NM: Green Lion Press, 2002), 1000a5.

3 Richard D. McKirahan, Philosophy Before Socrates: An Introduction with Texts and Commentary (Indianapolis, IN: Hackett Publishing Company, 1994), 181.

4 McKirahan, Philosophy Before Socrates, 267.

5 McKirahan, Philosophy Before Socrates, 346.

6 Sophist, 232b.

7 Sophist, 232c.

8 Sophist, 232e. The Eleatic Stranger mentions the "Protagorean writings on wrestling" specifically in this regard.

9 Plato, Meno, trans. W.R.M. Lamb (Cambridge, MA: Harvard University Press, 1952), 9 Ie.

10 Aristotle, Rhetoric, in Plato's Gorgias and Aristotle's Rhetoric, trans. Joe Sachs (Newburyport, MA: Focus Publishing, 2009), 1402a20.

11 At Physics 186al, Aristotle says that "Melissus and Parmenides reason like debaters."

12 Metaphysics, 1062bl2.

13 Metaphysics, 1007a22.

14 Metaphysics, 1007b20.

15 Metaphysics, 1062b25.

16 Metaphysics, 1062b24.

17 "Physics, 191a25.

18 Plato, Theatetus, trans. Seth Bernadette (Chicago: University of Chicago Press, 1986), 183b. Emphasis added.

19 McKirahan, Philosophy Before Socrates, 380.

20 Sophist, 248a. Compare with Aristotle, On the Soul, book 2, chapter 12.

21 Sophist, 249c.

22 Metaphysics, 1008blO-30.

23 Theatetus, 184a.

24 Physics, 191b5. I heard this golf example from Lance Simmons, whose seminar on philosophy of Being at the University of Dallas greatly influenced my thinking on these topics. It is a good example because the English verb "golf and noun "golfer" nicely share the same base, just as iatros and iatreuei do in Greek. Ralph Mclnerny also used this example in Aquinas: Classic Thinkers (Maiden, MA: Polity Press, 2004), 54.

25 Aristotle both says that "nothing comes into being simply from what is not, but surely in some way a thing comes into being from what is not, for example incidentally" (Physics, 191bl5) and that "likewise, neither does a thing come into being from what is, nor does what is come into being, except incidentally" (Physics, 191bl9).

26 Physics, 191b25.

27 Physics, 191b30.

28 Sophist, 263b.

29 Metaphysics, 1032b32.

30 Metaphysics, 1062b30. Aristotle or a subsequent editor crossreferences the Physics in this same sentence: "it has been said in the writings about nature."

31 Physics, 186a26. Aristotle's Metaphysics, book 7, focuses on the senses in which "being" is meant and offers further clarification of the Parmenides problem.

32 Physics, 186a34.

33 Physics, 186bl2. "The very thing which is cannot be a being." Aristotle also makes the different (but significant) claim at Physics 186b34 that: "The very thing which is cannot be an attribute of anything."

34 Physics, 187a10.

35 Physics, 20IaIO. Joe Sachs makes an interesting comment about the relation between motion and the distinction of form and material on page 48 of his translation: "Aristotle is often accused of taking this distinction from the realm of art and imposing it arbitrarily on nature. One needs only read chapters 5 through 9 of book 1 of the Physics to see that this distinction is in fact deduced as a necessary condition of change in general."

36 See Aristotle's On the Soul, 424al7-22.

37 Sophist, 216a.

38 Sophist, 216c.

39 Sophist, 217e.

40 Sophist, 254a.

41 Sophist, 236e-237a

42 Sophist, 237b.

43 Sophist, 24Oc.

44 Sophist, 238c.

45 Sophist, 239d.

46 Sophist, 239a.

47 Sophist, 23Sb.

48 Sophist, 26Oc.

49 Sophist, 256d5.

50 Sophist, 260b5.

51 Sophist, 257b2.

52 'Sophist, 26Od.

53 Sophist, 258e.

54 Sophist, 263c.

55 Sophist, 244e.

56 Sophist, 245a

57 Sophist, 253c.

58 Sophist, 253c. One cannot help but think of Aristotle's description of the "science of being qua being" in book 4 of the Metaphysics when reading this passage in the Sophist.

59 Sophist, 265b7. At Sophist 248c, the Stranger says "the definition of the things which are" is that they have "the power of being affected or affecting," and at 247e, "'the things which are' are not anything else but power."

60 Sophist, 265e.

61 Sophist, 256d and Sophist, 259a,

62 Metaphysics, 1089a5. Compare with Sophist 258d.

63 See, Aristotle's Metaphysics book 7 and Plato's Sophist 244e-245a.

64 Theatetus, 166a-168c. Socrates uses court language throughout the discussion, asking what court arguments Protagoras would offer in response at 178e.

65 Aristotle, On Sophistical Refutations, trans. E.S. Forster (Cambridge, MA: Harvard University Press, 1955), 164a20.

66 On Sophistical Refutations, 182blO-182b30. See also On Sophistical Refutations, 167al-20 for a discussion of fallacies connected with per accidens predication. "That which is not" and "that which is" are specifically mentioned.

67 Aristotle's example of the doctor who heals and the doctor who builds a house are easier to detect, and demonstrate the pattern. See Physics, 191b5.

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Correspondence to: C. J. Wolfe, School of Politics and Economics, Claremont Graduate University, 150 E. 10th Street, Claremont, CA 91711.

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