1. Introduction

It must be appreciated how tremendously influential Platonic philosophy has been in Western intellectual history—including Christian theology—so influential that it is probably impossible ever to catalogue the effects of that influence (this philosophers call effective history). Whether one realizes it or not, all participants in Western civilization bear the influence of Plato. For good or for ill, Plato stands as one of the pillars of Western civilization. What exists as a basis for the reconstruction of Plato's philosophy is his dialogues, all of which seem to have survived; it appears that these were composed with a general readership in mind, but also studied at Plato's school.  In addition, several letters that Plato wrote to various people have been preserved.  Plato taught near or at the gymnasion at Academos, near Athens; presumably, he spoke from notes and his students may have recorded some of his lectures.  This lecture material, however, did not survive in any form.  Now if Plato incorporated every aspect of his philosophy into his dialogues and letters, then the loss of this lecture material would be insignificant. Although it may be preferable to have Plato's lecture material, because likely he would have been more direct and comprehensive in setting out his philosophical position in them as compared to his dialogues and letters, nevertheless, the historian of philosophy would not be at disadvantage without this lecture material. Unfortunately, since Aristotle's discussion of Plato's views reveals that Plato's philosophy was more comprehensive than his dialogues would indicate, it seems that Plato differentiated his audience, so that he withheld some of his philosophical doctrines from the general public, teaching these privately to his students; in other words, Plato had an exoteric and an esoteric teaching.  The latter is only accessible now by way of what Aristotle says about Plato's philosophical beliefs.

     It is generally agreed that Plato wrote his many dialogues throughout his philosophical career, so that theoretically they are classifiable according to the time period in which they were written. There is some dispute, however, over the chronological order in which Plato's dialogues were written, for there is inadequate evidence from the dialogues themselves for their relative dating. Moreover, in spite of being written at different times in his life, Plato's dialogues manifest no significant development in philosophical outlook; with a few exceptions, they tend to present a uniform perspective. Now it is true that some possibily later dialogues take up topics not dealt with in other, possibly earlier ones, but one should not see this as development in the sense of a major revision of his previous views. Rather, it is a further development of a pre-existing ideas. Thus, it is preferrable to approach a summary of Platonic philosophy synchronically. In terms of method, it should be noted that not every dialogue is as useful as the others as means of reconstructing Plato's philosophy. (Some dialogues, for example, have no conclusions.) There tends to be a common core of dialogues deemed to be the most useful in this regard. Plato's more significant dialogues include used in the following summary of Plato's philosophy are Apology, Crito, , Meno, Cratylus, Phaedo, Philebus, Symposium, Republic, Theaetetus, Critias, Parmenides, Phaedrus, Sophist and Timaeus.

2. Biographical Information

Plato was born in Athens c. 428/7 BCE, and belonged to a distinguished Athenian family.  As a young man he had a close association with Socrates.  He describes him as "the most just man of his time" (VIIth Letter 324e).  After the fall of the "Thirty" in 403 BCE (This revolutionary, aristocratic government came to power in 404 BCE), Athens became democratic once again.  But some in power—Anytos in particular—brought accusations against Socrates, which Plato considered to be spurious (see Apology). Nevertheless, Socrates was executed for his alleged crimes, after which Plato left Athens and went to Megara.  Later, he traveled to Egypt, Magna Graecia and Sicily, where, it seems, he became acquainted with Pythagoreanism.  Returning to Athens, Plato founded his own school, in the groves near the gymnasion at Acadêmos.  During his three visits to Sicily, Plato attempted to convince the older and younger Dionysios to implement reforms consistent with his ideal system of government, but was unsuccessful.  He died in his eightieth year.

3. Platonic Epistemology

3.1.  Theaetetus

Although the problem of epistemology comes up in several of his dialogues, Plato dedicates the Theaetetus to this philosophical question. Using Socrates as his mouthpiece, he takes up the question of the nature of knowledge, what it means to know something. Socrates's partner in dialogue is Protagoras, the Sophist, although he is dead at the time that the dialogue is taking place; his views are presented by Protagoras's admirers and followers. As will become evident, epistemologically, Sophism is diametrically opposed to Platonism.

3.1.1. Wisdom as Knowledge

The dialogue begins with Socrates engaging Theaetetus, a student of Theodorus, in dialogue; he asks the question, "What is wisdom (sophia)?" By means of his dialectical method, he determines that wisdom is no different from knowledge (epistêmê), so that the two terms are synonyms. The dialogue then shifts to the question of the nature of knowledge. (Theaeteus 145d - 146a)

3.1.2. Protagoras's View that Knowledge is Perception.

Theaetetus eventually puts forth the proposition that knowledge is perception (ouk allo ti estin epistêmê ê aisthêsis), a view which is attributed to Protagoras the Sophist. To say that knowledge is perception is to say that what one perceives is true, so that perceptions are the objects of knowledge. This epistemology conforms to the Protagorean principle that,  "Man is the measure of all things (pantôn chrêmatôn metron einai anthrôpon)," or, more exactly, each individual perceiver determines through his perceptions the nature of reality. The implication of the Protagorean definition of knowledge is the denial of any transcendental standard of truth, independent of the individual knower, to which the knower is subject. It is also a denial that there is a reality to be known independent of one's own perceptions: either nothing exists beyond perception or whatever exists is unknowable. What you perceive is knowledge for you; there is nothing "behind" the perception, which you attempt to grasp or lay hold of by means of your perception; what is, is defined by your experience (sense perception). (Theaetetus 151d - 152a )

    Socrates admits the truth of the Protagorean principle in a limited number of cases. For example, whether a wind is cold is relative to the perceiver; if someone does not perceive a wind to be cold that you perceive as cold, you cannot rightly say that the other person's perception is wrong. Socrates then draws the further conclusion that, for Protagoras, appearance is knowledge because perception is nothing more than how things appear to a perceiver.  From this, Socrates concludes that for the one who espouses the Protagorean epistemology, it is wrong to say that something is, because something becomes what it is for us as it meets one of the senses. Perception requires a patient, a sense organ, and an agent, a potential perception (which one could call a stimulus); there is no perceiving, perception nor object perceived until the agent and patient are united. Thus, one cannot say that something is, but rather that it becomes for a perceiver what it is.  Likewise, one cannot say that an object perceived is the same object perceived at an earlier time, because this presupposes that an object exists independently of being perceived.  In other words, there can be no stable entities in existence, but only many perceptions from which one, out of convenience, infers the existence of a thing. (Theaetetus 156a - 157c)

Do you agree that knowledge is perception? If so, can you live with the consequences? If not, how does sense perception relate to what is?


3.1.3. Modification to the Protagorean Definition of Knowledge

Socrates offers objections to Protagoras's position. First, he points out that on Protagoras's definition, one cannot say that the perceptions of a madman are "wrong," nor can one distinguish between perceptions in dreams and waking life. But both implications go contrary to common sense, and would find no general acceptance. Second, if "Man is the measure of all things," then no one would be wiser than anyone else, including the gods, so that it hard to justify the status attributed to Protagoras as a teacher. Third, if perceiving is knowing, Socrates asks, why does not hearing a foreign language lead to knowing it? Or why does not seeing letters mean that one can read? Fourth, Socrates points out that one can know something by remembering it, but memory is not perception.

    Out of a sense of fairness, Socrates puts forward a rebuttal of his objections on behalf of Protagoras.  He has Protagoras distinguish between what is true and what is better. While it may not be truer than that of someone else, one person's perception may nonetheless be better, if the majority makes this determination. For example, if the majority decides that one mode of being ("wisdom") is "better" than another mode of being ("foolishness"), then it is, so long as the majority do not change its collective mind.  In such a social context, there is a place for teachers—Sophists—to help students learn how to be "wise" (Theaetetus 166d - 167d).

    Socrates concludes by pointing out the self-defeating character of an all-inclusive relativism, such as espoused by Protagoras: if "Man is the measure of all things," as Protagoras asserts, then the statement itself is relative, so that the opposite statement would be equally as true if someone thought it to be so.  This means that, in some cases, Protagoras would be wrong when he is right, i.e., if it appeared to someone that man was not the measure of all things.  (Theaetetus 170e - 171c)

Do you agree that relativism destroys itself as an epistemological theory?

    After more dialogue, Socrates proposes a correction to Protagoras's position that knowledge is perception: rather than saying that what one knows is what one perceives, Socrates asserts that what one knows is known through (by means of) perception; this will prove to be a radical shift away from Protagorean relativism. Socrates determines that there must be a "mind" (psuchê) that forms an opinion about or judges perceptual data, because it is possible to consider of two different types of sense objects at once (e.g., sound and color) and to compare them in certain respects that they have in common or to abstract from both what they share in common. Theaetetus understands Socrates's point: "You are thinking of being and not being, likeness and unlikeness, sameness and difference, and also of unity and other numbers which are applied to objects of sense; and you mean to ask, through what bodily organ the soul perceives odd and even numbers and other arithmetical conceptions."  It is the mind that "manages" perceptual data, as it were; only it can grasp "truth" and "existence," since these are categories applicable generally to sense data, not one particular type of perception (186d). Since knowledge is forming of an opinion or a judgment with respect to the "truth" and "existence" of an object, it follows that it is the mind alone that knows and not the five senses, the means of perception. In other words, "The mind, by a power of her own, contemplates the universals in all things (ta koina...peri pantôn)."  The universals are those attributes applicable to many different perceptions, but not given directly in perception; one of these universals is existence and its opposite, non-existence. (Theaeteus 184d - 185e)

    One could expand on Socrates's point on the function of the mind. One could say that the mind takes the perceptual data and constructs from them objects of knowledge; the mind combines different perceptions into a single object. The objects that the mind constructs from sense data, which is by its very nature fleeting and impermanent, are stable—albeit hypothetical—and can be perceived again. Knowledge thus is no longer perception; rather perception provides the data from which the mind constructs what is; what is somehow causes the perceptual data but are not simply identifiable with them. When perceptual data do not exist the objects of perception hypothetically still do.

Does "mind" (or whatever term you want to use) exist?  If so what is it, and how does it relate to the five sense?

    Having determined that knowledge is not perception, Theaetetus then proposes a new definition of knowledge more in line with this new way of thinking:  true opinion or judgment is knowledge (hê aleithês doxa epistêmê einai). True opinion or judgment is the mind's construction from perceptual data of objects that are self-existent, existing apart from their being perceived and that correspond to the things of which they are thoughts. This is a version of the correspondence theory of knowledge:  knowledge is the correspondence between the known and the contents of a knower's mind as expressed propositionally or schematically. (Theaetetus 186e - 187b)

Would you define knowledge as correspondence between the known and the contents of the knower's mind?


3.1.4. Attempt to Define the Nature of False Opinion or Judgment

Socrates then discusses the nature of false opinion or judgment with limited success. He rejects the idea that in thinking falsely one is thinking about nothing, because one cannot think about nothing. Among the tentative conclusions reached are that false opinion or judgment can occur when the mind wrongly associates something known (objects of thought) and held in memory with a perception. Also error can arise through not successfully retrieving knowledge already possessed from the memory, but instead mistaking another piece of knowledge for it. To this latter assertion, however, Socrates raises some doubt that possessing knowledge could ever lead to not knowing. In the end, Socrates abandons the question of the nature of false opinion or judgment, and returns to seeking for a definition of knowledge, for without such a definition, one cannot define the nature of false opinion or judgment.

3.1.5. Further Modification to the Working Definition of Knowledge

Socrates determines that true opinion or judgment cannot be knowledge, because one may unintentionally make a true judgment, and this surely cannot be called knowledge. In response Theaetetus qualifies his previous definition of knowledge by saying that it is true opinion or judgment with logos (reason), i.e., an explanation or justification for its acceptance as truth. (Theaetetus 200e - 201d)

    Socrates then discusses just what this logos might be. He proposes three definitions of this logos:  1. It is an articulation of the true opinion or judgment; 2. It is an enumeration of the component parts of the true opinion or judgment; 3. It is the ability to differentiate the object of true opinion or judgment from other objects. Unfortunately, Socrates rejects each of the three definitions of logos as inadequate, and this is where the dialogue ends.

What makes a proposition knowledge as opposed to merely a "lucky guess"?  In other words, what is the logos that Socrates is seeking?


3.1.6. Conclusion

Although the dialogue falls short of providing a complete theory of knowledge, Theaetetus at least puts forward two epistemological assertions: 1. Knowledge is not perception, because the mind is operative in the process whereby someone comes to know; rather knowledge is true opinion or judgment; 2. Knowledge corresponds to what it, rather than, on Protagorean theory, being relative to the knower; there exists realities outside of the mind of the knower that the knower must then attempt to understand and represent in symbolic terms.


3.2. Cratylus

The theme of the dialogue Cratylus concerns the origin and nature of language, and for this reason is important for an understanding of Platonic epistemology. The question addressed is whether names are conventional or whether there is a certain fittingness to or naturalness to names. Although he is in dialogue with both Hermogenes and then Cratylus, Socrates' real partners in conversation are first the Sophist Protagoras and then Heraclitus. Early into the dialogue, Protagoras's dictum "Man is the measure of all things" (pantôn chrêmatôn metron einai anthrôpon) is rejected as contradictory, for if the truth were as it appeared to each individual, then no one could be wise, which is patently false (386a-e). Socrates concludes that all things are not relative to the individual: "It is clear that things have some fixed reality of their own (auta autôn ousian exchonta tina bebaion esti' ta pragmata), not in relation to us nor caused by us; they do not vary, swaying one way and another in accordance with our fancy, but exist of themselves in relation to their own reality imposed by nature (pros tên autôn ousian exchonta)" (386d-e). This means that, in order to be correct and meaningful, words—both nouns and verbs—must correspond to realities that exist independently of the human consciousness. Thus, Socrates adopts a correspondence theory of truth.

    Socrates then draws the further conclusion that words are instruments for distinguishing natures: "A name is, then, an instrument of teaching and of separating reality" (onoma ara didaskalikon ti estin organon kai diakriton tês ousias) (388c). A name identifies a reality (ousia) existing independently of the knower and so distinguishes this reality from other realities. A name thus becomes suitable to teach others concerning this reality. The dialectician serves to aid the one appointed to the task of assigning names (if this were possible), for the former seeks to understand the realities through the dialectical process (390c-d).

Do you agree that names must reflect reality or do you think that language is merely conventional, a human construct that creates a world rather than reflects the structure of an already-existent world?

    After much linguistic analysis in which he demonstrates that names are natural, in the sense of being expressive of the realities that they name, Socrates explains that the original givers of names gave them on the mistaken assumption, as Heraclitus said, that "all things were in motion and flux" (439c). In effect, this meant that they did not look beyond sensible experience to seek after the things themselves, such as beauty itself (auto kalon) or good itself (auto agathon) (439c). Along the same lines, he also distinguishes between knowing the realities "through names" and knowing the realities "through themselves." He asks,

Then if it be really true that things can be learned either through names (di' onomatôn) or through themselves (di' autôn) which would be the better and surer way of learning? To learn from the image whether it is itself a good imitation and also to learn the truth which it imitates, or to learn from the truth both the truth itself (ek tês aleitheias autên) and whether the image is properly made? (439a-b)

In other words, he proposes the possibility of knowing these realities directly, without the mediation of language; he no doubt means the eternal unchanging realities themselves, such as beauty itself and good itself. This is clearly better epistemologically than knowing a reality in the flux of perceptual experience by means of a name that reflects the nature of that reality. Socrates expresses doubt, however, that such a knowledge is possible: "How realities (ta onta) are to be learned or discovered is perhaps too great a question for you or me to determine; but it is worth while to have reached even this conclusion, that they are to be learned and sought for, not from names but much better through themselves (ex autôn) than through names." Whether it is possible ever to do so, Socrates at least has established the epistemological desirability of knowing the realities through themselves. Nevertheless, Socrates does exhort Cratylus to seek the beauty itself: "Then let us consider the thing itself, not whether a particular face, or something of that sort, is beautiful, or whether all these things are in flux. Is not, in our opinion, beauty itself always such as it is?" He then continues by denying that knowledge (gnôsis) can be of anything that is in flux and is not permanent, such as perceptual data are. He says,

But we cannot even say that there is any knowledge, if all things are changing and nothing remains fixed; for if knowledge itself does not change and cease to be knowledge, then knowledge would remain, and there would be knowledge; but if the very essence of knowledge changes (auto to eidos metapiptei tês gnôseôs), at the moment of the change to another essence of knowledge there would be no knowledge, and if it is always changing, there will always be no knowledge, and by this reasoning there will be neither anyone to know nor anything to be known. But if there is always that which knows and that which is known—if the beautiful, the good, and all the other realities (ontes) exist—I do not see how there is any likeness between these conditions of which I am now speaking and flux or motion.

Knowledge requires a permanent knower and a permanent object to be known. If one or both are in flux, changing their natures constantly, then there can be no knowledge. As Plato expresses it, if the "essence itself of knowledge" changes insofar as knowledge is now defined no longer by the permanence of the knower and the object known then knowledge would no longer exist. It is clear that, for Plato, knowledge requires for its object the unchanging realities and not the flux (roa) or motion (phora) characteristic of perceptual data. In other dialogues, Plato calls the permanent thing itself as the only object of knowledge ideas.


Do you agree that knowledge can only be of the permanent?

4. Doctrine of Ideas and the Soul

The tentative epistemological conclusions in Theaetetus and Cratylus anticipate Plato's doctrine of Ideas (ideai or eidê) (Plato's "Ideas" are often called "Forms," since forma is the Latin translation of idea or eidos.) His doctrine of Ideas is inseparable from his conception of the soul, since the soul is what knows the Ideas. As was seen, Aristotle reports that Socrates sought after universal definitions. The question that Plato asked is what is the ontological status of these universal definitions and how is it that human beings can know these?  His answers to this question constitute his teaching about Ideas and the soul.  An effective approach to this investigation is to examine relevant dialogues or parts thereof where these two concepts are discussed at length.

4.1. Phaedo

4.1.1. The Philosopher and Death (Phaedo 59c-70c)

In the dialogue Phaedo, Socrates is speaking with some of his friends and followers in the last hours of his life. Fittingly, the question that he undertakes to investigate is whether the soul (hê psuchê) is immortal. Socrates affirms that the man who has devoted himself to philosophy should be cheerful in the face of death, for, during his whole life, the philosopher has been preparing himself for death (59c-70c). The philosopher's goal has been to become as independent of the body as possible, so that death is really only the ultimate independence of the soul from the body.  During this discussion, Socrates explains that it is the soul alone that can understand absolutes (things themselves)—"the essence or true nature of everything" (apantôn he ousia)—such as justice, beauty or good; the body with its sense organs can only perceive individual things, not the absolutes that inhere in the individual, but the true nature (alêthestaton) of the individual thing. (Phaedo 65d - 66a Socrates then advises that one ought to be rid of all bodily distractions as much as possible, in order to become wise, because wisdom consists in the soul's knowledge of absolutes. It follows that death will be an advantage to the philosopher, because no longer will the body be able to distract the soul.

4.1.2. Arguments for the Immortality of the Soul (Phaedo 70c-80c)

Upon hearing of Socrates's discourse on the philosopher and death, Cebes asks whether Socrates knows that the soul can actually survive death; it is one thing to say that the soul is impeded by the body but something else to prove that it survives its dissolution. There follow three arguments for the soul's immortality.

    First, Socrates argues that, since opposites are generated from opposites that life must be generated from death. Since the principle of life is the soul, then the soul must survive death, or else life would soon cease. (Phaedo 70d - 72a) (This is the basis of belief in the reincarnation of souls.) Second, Socrates argues that, since learning is recollection, the soul must have pre-existed or else there would be nothing to recollect; when the soul enters the body it "forgets" what it once knew and must "recollect" it.  Added to this is the fact that human beings have an innate knowledge of absolutes by which to judge perceptual data, which they recollect as they receive these data. For example, one needs to have knowledge of "equality itself" to be able to judge two objects to equal or unequal in some respect.  Socrates concludes that the knowledge of these "absolutes" are innate in the soul, although it has been forgotten, which means that the soul must pre-exist its incarnation in the body. (Phaedo 75c - 76c)  Thirdly, Socrates argues that, since it is like the Ideas in its invisibility and incorporeality, the soul must also be incomposite as they are, which means that the soul is incorruptible. In this context, Socrates contrasts the realm of invisible, unchanging absolutes with that of the realm of the visible and changing material exemplifications of these absolutes. To the former belongs the soul, while to the latter belongs the body. When the soul contemplates the absolutes, being free from the impediments of the body, it enters into the condition of wisdom (phronêsis).  Socrates describes this as passing "into the realm of purity, and eternity, and immortality, and unchangeableness." (Phaedo 78c - 79d)

Do you find Plato's arguments for the immortality of the soul convincing?  If not, what are the flaws in the argument?


4.1.3. The Body and the Soul (Phaedo 79d - 84b)

Socrates then explains that, upon the death of the body, the soul goes to the realm of the invisible, pure and noble, into the realm of the good and wise God. If it has remained uncontaminated by contact with the now-deceased body, then the soul may remain in this realm. Souls that are so contaminated, however, return to the realm of the visible and changing to be reincarnated. The philosopher is the one whose soul is able to go beyond the realm of the visible, and sees the true reality, which is intellectual and invisible (Phaedo 79d - 83c). Souls that practice philosophy attain to the divine nature (Phaedo 82c).

4.1.4.  Ideas as Causes (Phaedo 99c - 105b)

Socrates argues that things in the realm of the visible and changing are what they are insofar as they participate in the Ideas; they cause things to be what they are, allowing individual things to be identified as an instance of a universal. Beautiful things are beautiful because they participate in (metechein) beauty itself. He says, "For I cannot help thinking that if there be anything beautiful other than absolute beauty, that can only be beautiful in as far as it partakes of absolute beauty-and this I should say of everything" (100c). These absolutes are named Ideas, and visible and changing things that bear the name of an Idea are so named because they participate in that Idea. This is Plato's theory of causation (aitia): the Ideas cause individual things to be what they are. (Phaedo 100b - 100e)

Is it true that for there to be beautiful things there must exist beauty itself?  If you do not agree, how do you account for the existence of abstractions such as beauty or the beautiful?


4.1.5. The Soul as Partaking of the Idea of Life (Phaedo 105b - 107a)

Socrates argues further  that the soul is immortal because it participates in the Idea of life, thereby giving the body life; if the soul participates in Idea of life it must be immortal, since opposite Ideas cannot co-exist.

4.2. Phaedrus

In the midst of a rather distasteful discussion of homosexual love, Socrates expounds on the soul and beauty itself. Reversing his earlier position that love (eros) is an evil, Socrates now argues that the madness of love is the greatest of the blessings of heaven. The love of physical beauty is the first step towards a knowledge of a love of beauty itself.  As a preliminary to his establishing this position, Socrates discusses the soul.

4.2.1. The Immortality of the Soul (Phaedrus 245c - 246a)

Socrates affirms that the soul is immortal, because it is the nature of the soul to be self-moving and therefore eternally moving: "For that which is ever in motion is immortal" (to gar aeikinêton athanaton). It is the nature of the soul to be immortal, since motion is life. In addition, the soul is the first principle of motion (archê kinêseôs) in the body; without the soul there can be no motion. Since a first principle is unbegotten, it is indestructible. The soul as first principle of bodily motion, therefore, is unbegotten and indestructible. (Phaedrus 245c - 246a).

Does the body need a principle of life to be alive?  Is the idea of a soul an illusion?


4.2.2. The Chariot Metaphor  (Phaedrus 246a - 250c)

Socrates now turns his focus on the nature of the soul. He compares the soul to a winged charioteer who controls two winged horses, one good and the other evil, representing the good and evil natures of human beings. The winged charioteer, like the gods, should aim to ascend to the highest sphere, beyond the heavens, where she will behold Being itself or "truly existing existence" (ousia ontôs ousa), "with which true knowledge is concerned; the colorless, formless, intangible essence, visible only to mind" (achrômatos te kai aschêmatistos kai anaphês...psuchês kubernêtêi monôi theatê nôi, peri hên to tês alêthous epistêmês genos) (247c). As the sphere rotates, the soul sees also "justice, and temperance, and knowledge absolute, not in the form of generation or of relation, which men call existence, but knowledge absolute in existence absolute (tên en tôi ho estin on ontôs epistêmên ousan)" (247d - 247e). It is not, however, that the soul beholds the absolutes for the first time, because, being immortal, the soul has already had a contemplation of "Being itself." Socrates says, "For, as has been said, every soul of man has by nature beheld the beings" (pasa men anthrôpou psuchê phusei tetheatai ta onta) (249d - 250a); when the soul in its embodied state manages to grasp the highest reality, it is only recalling what it already knew. It is clear that this "myth" is intended to communicate the distinction between the realm of the visible and changing from that of the intelligible and unchanging. The soul's task is to apprehend the latter, in spite of the hindrance of  the body. Moreover, it seems that ontologically (as opposed to spatially) beyond the realm of Ideas is Being itself (or "truly existing exisence"), which has no qualities at all, being beyond all distinctions. Those souls that behold "Being itself" will escape from the necessity of rebirth into the realm of the visible and changing.  (Phaedrus 246a - 248c).

What is this Being Itself of which Plato speaks?  Is it to be identified with God or the divine?


4.3. Republic 5-7

The doctrine of Ideas finds its most complete expression in Republic 5-7; the discussion up to Republic 5 deals mostly with political and social issues, but in Republic 5-7 the conversation turns towards the nature of philosophy and the philosopher. This is because Plato's ideal ruler is the philosopher/king: to be a good ruler one must be a philosopher. Necessarily, therefore, Plato must describe what a philosopher is.

4.3.1. Republic 5

Towards the end of Republic 5, Socrates, acting as Plato's literary mouthpiece, says that the philosopher are "lovers of the visions of the truth" (475e). He then differentiates between knowledge (gnôsis) and ignorance (agnôsia): the former has Being (to on) for its subject-matter or object, while the latter has non-Being (to mê on). In other words, to know is to know what is, while not to know is to "know" nothing, which is really impossible. There is, however, an intermediate cognitive faculty, which Socrates calls opinion (doxa); it stands between knowledge and ignorance partaking of both. The subject matter or object of opinion likewise partakes of both being and non-being. To opine is to recognize the participation of the objects of perception in absolutes but without being to recognize the absolutes themselves. For example, a man may perceive and name many beautiful things, but not be aware of beauty:  "Then those who see the many beautiful (polla kala), and who yet neither see beauty (to kalon), nor can follow any guide who points the way thither; who see the many just, and not justice, and the like—such persons may be said to have opinion but not knowledge?"  (479e)  Opinion is what Plato calls knowledge of the manifestations of the Ideas in the sensible world, but without differentiating the Ideas from that which which participate in the Ideas. The objects of opinion are in constant flux, so that opinion by its very nature is impermanent; this is why it cannot be knowledge, because knowledge has for its object what is permanent (Being). But because it  recognizes the presence of the Ideas in sensible world, opinion cannot be called ignorance either. (Republic 5 [473c - 480])

Must one posit the existence of "Absolutes" in order to speak of something as something?  What does knowledge have as its objects?  What alternatives might there be to Plato's position? 


4.3.2. Republic 6

In Republic 6, Plato expands upon his philosophical reflections begun in the previous chapter. Socrates continues his discussion of the nature of the philosopher, who, ideally, will rule the State. He is defined as one who is able "to grasp the eternal and unchangeable" (hoi tou aei kata tauta hôsautôs echontos dunamenoi ephaptesthai) (484b), and not be one who wanders "in the region of the many and variable." (484b).  (Republic 484b) The philosopher is one who contemplates the absolutes and is not content to live in the realm of perception. Further defining him, Socrates says that the philosopher loves "knowledge of a sort which shows them the eternal nature not varying from generation and corruption" (485b) (ekeinês tês ousias tês aei ousês kai mê planômenês hupo geneseôs kai phthoras).  (Republic 485b)  In other words, the philosopher seeks to know the Ideas. After describing by means of a parable how the philosopher should have control over the affairs of state, Socrates describes the philosopher as one who, a "true lover of knowledge" (philomathês) always strives to know "the true nature of every essence" (to on), not being content with the multiplicity of individual things. What is meant is that the philosopher seeks the absolutes, the Ideas, in which individual things called by the name of that absolute participates  (Republic 490a - b). Socrates then explains that the true philosopher looks upon the fixed and immutable order (all' eis tetagmena atta kai kata tauta aei echonta horôntas), by which is meant the system of Ideas; in this way the philosopher "holding converse with the divine order (theioi dê kai kosmioi), becomes orderly and divine, as far as the nature of man allows" (500 c-d). When compelled to take control of the state, the philosopher will fashion a constitution that is an expression of the absolute justice and beauty and temperance. (Republic 500a - 501d)

    Those with an inborn capacity for philosophy should be nurtured in their philosophical development, in order that they may be fit to take power.  Socrates contrasts this ideal education with what the Sophists provide the young; the differences are fundamental and presuppositional. Socrates criticizes the Sophists for equating knowledge with popular opinion; in other words, the Sophists wrongly espouse a form of relativism, equating reality with what the majority say of it. The task of the Sophist educator is to train the young to know popular opinion, in order to operate effectively in that social context.  (Republic 493a - 494a)

     Later in the chapter, somewhat unexpectedly, Socrates asserts that those philosophers in training to be rulers must reach the highest knowledge of all, which is the knowledge of the Good (to agathon). Glaucon then asks Socrates about the Good. (For the sake of orderliness of presentation, it is preferable to postpone a discussion of the Good until later.)  This discussion leads eventually to Socrates's attempt to classify the types of cognitional activity and their corresponding subject matters or objects; these are set in a hierarchy that reflects the degree of truth and reality of the corresponding subject matters or objects and therefore the relative importance of the cognitional activities. The assumption is that something is more true and real insofar as it is ontologically more original; ontological originality is the attribute of having priority with respect to Being, i.e., being the cause or basis of other things, their principle or cause. Plato divides all cognitional activity into two types: section BC represents the intelligible whereas AB represents the visible. These two types are then each subdivided again into two types (AD, DB, BE and EC). It seems that the major division among the objects of cognitional activity is between knowledge (epistomê) and opinion (doxa), a distinction already introduced in Book Five. The objects of knowledge are the principles of mathematics and the Ideas, whereas the objects of opinion are the objects of the material world and representations of these.

     Eikasia (Representation) is the cognitive activity of perceiving sensible representations of perceptual objects; this is the lowest level of cognitional functioning, so that its objects have the least reality.  Pistis (Opinion)  is the cognitive activity of perceiving by means of one or more of the five senses; the objects corresponding to pistis are perceptual objects, i.e., material objects susceptible of being perceived by means of one or more of the five senses. Perceptual objects have greater reality than images of reflections, because the latter are derivative of the former in their being. One then moves above the line into the level of the intelligible. Dianoia (reasoning) is the cognitive activity of reasoning from first principles (i.e., axioms) to mathematical truths. What Plato calls noêsis (knowledge), on the other hand, is the understanding of Ideas or Absolutes by means of dialectic. These are the most true and real of all objects of cognitive activity. Ideas are essences or definitions—pure concepts—in which individual material things participate and become what they are. They are eternal, immaterial conceptual realities that provide the means by which visible things are classified. It must stressed again that for Plato the Ideas have objective reference; this means that they do not simply exist in the mind but that they really exist apart from their being thought and apart from their presence in the visible world.  It is only by means of the Ideas that one can have opinions of the visible world at all, because without them one could not identify anything as something, i.e., as an instance of an universal. (Republic 510d - 511d)

If you do not agree with Plato's view of Ideas, what are abstract concepts or generalizations?

    According to Plato, there is something more real than the Ideas or Absolutes. This necessitates a return to the question of the Good. Socrates says that the Idea of the Good (hê tou agathou idea) is the greatest object of study, so that one Idea is elevated above the others (505a). He insists, however, that the Good  can only partially be known; he refuses to talk about the Good, but prefers to talk about the child of the Good, the sun. Why is the sun the child of the Good? The sun is related to sight as one of its conditions; it is not light or sight, but is the condition of both of these; one can say, in Plato's view, that light and sight are sun-like but not sun. To say that the sun is the child of the Good is to say that the sun functions in the visible world analogously to the way that the Good functions in the intelligible world, the realm of Ideas. The Good is the condition for the eyes of the soul to know its objects, the Ideas; the Good is not the eyes of the soul nor the Ideas, in the same way as the sun is not sight or light.

    Socrates actually says that Good gives truth (tên aleitheia) to the objects of knowledge and power to know (tôi gignôskonti tên dunamin) to the mind; it is the source of knowledge and truth and as such knowledge and truth are Good-like. Socrates explains,

Now, that which imparts truth to the known and the power of knowing to the knower is what I would have you term the idea of good, and this you will deem to be the cause of science, and of truth in so far as the latter becomes the subject of knowledge; beautiful too, as are both truth and knowledge, you will be right in esteeming this other nature as more beautiful than either; and, as in the previous instance, light and sight may be truly said to be like the sun, and yet not to be the sun, so in this other sphere, science and truth may be deemed to be like the good, but not the good; the good has a place of honor yet higher. (508e-509a).

To say that the Good gives the power to know to the mind is to say that the Good is manifested as consciousness. To say that the Good gives truth to the objects of knowledge is to say that the Good is the source of all the Ideas. And insofar as the Ideas are the source of all visible things, as that which makes them what they are, i.e., gives them intelligibility, the Good is the source of the visible world as well. In other words, the Good has ontological originality, being the first principle of all things. Thus, the Good is both absolute subject and object, the self-same principle of being and of knowing.

    Socrates stresses that the Good cannot be said to be the same as those things that are caused to be by the Good: "The good may be said to be not only the author of knowledge to all things known, but of their being and essence (kai to einai te kai tên ousian), and yet the good is not essence (ousia), but far exceeds essence in dignity and power" (509b). For Plato, the Good transcends essence, which means that it transcends the Ideas, which are the essences of all visible things. Thus, the Idea of the Good is not like the other Ideas; one can now understand why Socrates is reluctant to talk about the Good: one cannot talk about what is beyond essence. (Republic 504c - 509c)

Is it necessary to have one first principle, such as Plato's "the Good"?


4.3.3. Republic 7

In this chapter is found Plato's famous cave-metaphor; its purpose is to depict the ascent of the soul to the level of noêsis. The natural state of a human being is to be as if in a cave with his face permanently pointed towards the inside wall of the cave; between the people and the mouth of the cave there is a fire and between the fire and the people there is something like a screen. Behind the screen people walk carrying statutes of animals and human beings so that they cast shadows upon the inside wall of the cave. A person who has from childhood only seen these images and nothing else will naturally assume that these images are real, indeed the only real. This represents the level of eikasia.  If one broke free and looked at the statues causing the images, one would see that which has been causing the shadows.  This represents the movement to the level of pistis. Imagine then that the same person next ventured outside the cave and saw the objects of the world as illumined by the sun; this corresponds to the level of understanding wherein a person knows the Ideas (noêsis). Finally,  if he looked up at the sun, the same person would see that which causes one to see anything at all. This represents knowledge of the Good.  If this now-enlightened person went back into the cave and tried to convince his fellow-prisoners of what he had seen, he would scarcely be believed; thus his task would be the educate his fellow prisoners so that they can eventually come to understand.

    In Republic 517 b-c, part of the cave metaphor,  Plato makes two important points. First he speaks of "the ascent of the soul into the intellectual world" (tôn anô tên eis ton noêton topon tês psuchês anodon). Coming out of the cave into the light of day represents the soul's ascent through the levels of cognition to the level of knowledge ("the intellectual world") terminating in the contemplation of the Idea of the Good. Second, Socrates says of the idea of the Good that it is "the universal author of all things right and beautiful (orthôn te kai kalôn), parent of light and of the lord of light in this visible world, and the immediate source of reason and truth in the intellectual; and that this is the power upon which he who would act rationally, either in public or private life must have his eye fixed." The Good is the cause in the visible world of light and the source of light (sun); in the intelligible world, the Good is the cause of knowledge and truth. Thus, it would seem that Plato thought that there was more than simply an analogy between the sun and the Good: the sun is the actual manifestation of the Good in the material world in addition to being analogous to it in its function. (Republic 514a - 517c)

4.4. Parmenides

In the dialogue Parmenides, Socrates converses with Parmenides concerning the question of how things in the visible world relate to Ideas (eidê); this is the problem of how the one is related to the many, for the visible manifestations of the Ideas are many. Parmenides aims to demonstrate that the belief in Ideas leads to absurdity. After summarizing Socrates's understanding of Ideas, Parmenides inquires into how the many individual things relate to the Idea to which these individual things are supposed to participate (metalambanein). Parmenides begins by having Socrates agree that he believes in the Ideas of likeness (homoia) and unlikeness (anomoia), in which the many individual things participate. In this way, one thing may share in opposite attributes, insofar as it participates in opposite Ideas, so that one thing is both like and unlike other things. Socrates also explains that it is not strange that a thing can be one, insofar as it participates in the Idea of unity, but also be many, insofar as it participates in the Idea of the many and thereby has parts. It is not true to say, however, that unity is many and many unity (128e-130a). Parmenides then asks Socrates whether there are Ideas of things not only such as man, fire, water, but also such things as "hair, mud, dirt, or anything else which is vile and paltry." (130b-d). Socrates responds that he once thought this but now recoils from the position that all perceptual objects have Ideas. The point, it would seem, is that such things are too trivial and lowly to have Ideas in which they participate. (That this is Plato's view, however, does not seem to be the case.) (Parmenides 130a - d)

    Socrates proposes that individual things participate in (metalambanein) Ideas; this is put forward as an explanation of  how the two are related. Parmenides then seeks to draw absurd conclusions from this assertion, thereby refuting it. He asks whether individual things participate in the whole Idea or part thereof. On the first hypothesis, it follows that the entire Idea is found in every individual thing, which leads to the absurd conclusion that the one, by definition a unity, will be separated from itself. On the second hypothesis, it would follow that parts of the one Idea are found in the many individual things.  But this leads to absurdities, for the Idea of greatness, when divided, is no longer greatness, since it is now divided into a multitude of not-so-great parts. In response, Socrates says that one should not think of Ideas as magnitudes that can be divided, but as thoughts. Unfortunately, Parmenides finds this amendment unsatisfactory. If an Idea is a thought, then for something to participate in an Idea it must be a thinker, because there cannot be thought without a thinker; this means that all individual things think. (Parmenides 130e - 132c)

    Socrates's second proposed explanation for how individual things participate in Ideas is that the Ideas are patterns existing in nature (paradeigmata hestanai en têi phusei) that individual things imitate. Socrates says, "These ideas exist in nature as patterns, and the other things resemble them and are imitations of them; their participation in ideas is assimilation to them, that and nothing else" (132d). In other words, things are copies of an original Idea, with the result that the individual thing is not only like the Idea, but the Idea is like the individual thing. But if two things are alike, they must be so because they participate in the same Idea. So Parmenides objects that, were this so, there would be introduced necessarily a third "thing" (or Idea) to which the Idea and individual thing are more similar than they are to each another (otherwise they could not be said to be alike), and so on in an infinite regress. The assumption is that the Idea is an individual thing and that its copies are not exact duplicates of it. (Of course, this is not how Plato conceives Ideas.)  Parmenides adds that, if they existed, Ideas would be unknowable, because human experience concerns individual things and their relations to one another, not absolutes. Only the Idea of knowledge could know the Ideas. (Parmenides 132c - 134e)

    The dialogues continues with Parmenides's drawing innumerable conclusions from the assertion that Reality is One or Many. Since Parmenides is probably one of his later dialogues, it is possible that  Plato was reflecting further on the question of how an individual, visible things participate in the Ideas. The fact that the dialogue comes to no conclusion could indicate further that when he wrote Plato was still working through the question of how things in the visible world relate to the Ideas.

4.5. Sophist

The dialogue Sophist features a stranger from Elea, a devotee—at least initially—of Parmenides, in dialogue with Theaetetus. The conversation centers around the attempt to define a Sophist. The method employed by the stranger is that of classification by division into mutually exclusive types, the result of which is a hierarchy of concepts. Eventually, it is decided that Sophist is a type of illusionist, appearing to be wise in their pronouncements without actually being so. This conclusion, however, leads to the philosophical problem of non-being: the status of that which is not, but, as in the case of the Sophist, merely appears to be. As Parmenides would do, the stranger argues that what is not, cannot be spoken of as if it were, so that the definition of the Sophist is meaningless. The stranger adds that one cannot use attributes applicable to what is, in particular number, to refer to what is not. One cannot, for example, even speak of the non-existent, because in so doing one attributes to it the attribute of unity, nor can one refer to non-existent things, for this assumes that what is not, can be a plurality.

    It is agreed upon that to define the Sophist as a type of illusionist, one who deceives people into thinking that he is wise on a whole range of topics, leads to the inadvertent acceptance of the proposition that what is not, is. Deception and the resultant error must be defined as thinking that things that are, are not and that things that are not, are. But this contradicts the Parmenidean principle that one cannot speak of what is not as if it were and of what is as if it were not. In response to this quandary, the stranger takes the radical step of re-examining the Parmenidean principle that what is not, cannot be and therefore cannot be spoken of as if it were. This leads eventually to Plato's justification for the existence of false propositions, which in turn allows the definition of the Sophist to stand. (This issue was left unresolved in Theaetetus.)

    After considering the nature of non-Being, the stranger enters upon an examination of its opposite, Being. He begins by discussing the implications of saying that Being (to on) is one. Socrates inquires into how all can be said to be one when two Ideas are attributed to this alleged one thing: Being (on) and unity or oneness (hen). The result is that there are three distinct things: the alleged one thing and the two Ideas (or names). Socrates also concludes that Parmenides' view of Being as a sphere implies that it has parts (e.g.'s a middle and extremities) and so must have oneness or unity by virtue of something other than itself, in which case it is no longer one (242c-245e). Socrates then states that there are two views about the nature of Being. On the one hand, some say that Being is what can be perceived, i.e., the corporeal, while, on the other hand, there are those who claim that Being consists of intelligible and incorporeal Ideas. On the former definition, Being is in constant motion, while on the latter, Being is motionless. (It is clear that these two views correspond to those of Heraclitus and Parmenides respectively.) In a somewhat convoluted argument, the stranger argues that both positions are correct. He says that soul is the principle both of life (motion) and intelligence in that in which it finds itself, the animated. Thus, where there is no motion, there is no intelligence, since there is no soul; the result is that, if it consists of eternally unchanging Ideas, Being would be devoid of intelligence, because Being would devoid of soul, the principle of life (motion). But such a conclusion is impossible, since Ideas are by definition the intelligible. Conversely, if Being consists of the corporeal and moving, there would be no intelligence in Being, since intelligence presupposes the motionless, i.e., the Ideas; the point is that there is no intelligibility without the static Ideas, by definition the intelligible, since they are the principles of knowledge and Being, functioning as absolutes by which to order and classify the moving things.  Eventually, it is concluded that Being is not one or the other, but a third thing, incorporating both definitions of Being:  "So he will include both the moveable and immovable (akinêta kai kekinêmena) in his definition of being and all" (to on te kai to pan) (249d).

    The discussion next moves to a consideration of the nature of Being, in particular how Being can be both one and include within itself many things, some of which are opposites. (Knowing the nature of Being will aid in understanding the nature of non-being, which has still to be determined.) It is then asserted that the intelligible aspect of Being exists as a hierarchy of Ideas; this presupposes the existence of more abstract and less abstract Ideas, down to the infimae species (the lowest class before the individual thing) and the possibility that the less abstract Ideas can participate in the more abstract Ideas. The stranger explains,

Then he who is able to do this has a clear perception of one Idea extending entirely through many individuals each of which lies apart, and of many Ideas differing from one another but included in one greater Idea, and again of one form evolved by the union of many wholes, 253e] and of many Ideas entirely apart and separate. This is the knowledge and ability to distinguish by classes how individual things can or cannot be associated with one another. (253d-e)

Thus, there arises the possibility that two opposing Ideas can participate in the same, more abstract Idea.  For example, the Ideas of moving and non-moving both participate in the Idea of Being or existence.  Since they are the most abstract Ideas, the Ideas of Being and Difference occupy the top place of the hierarchy of Ideas: all other Ideas have existence and are different from all the other Ideas. The individual things that constitute the moving and perceptial aspect of Being likewise participate in Ideas, and they may participate in many Ideas of varying degrees of abstraction at the same time. A woman participates in the Ideas of female, humanity, animality, etc. at the same time. (Sophist 253b - 254b)

    It needs to be stressed that not all Ideas are capable of intermixture, being blended with other Ideas; in some cases—such as the hot or cold, the wet and dry, etc.—two opposing Ideas can never be so intermixed. The stranger says,

Then, surely, he who can divide rightly is able to see clearly one Idea pervading a scattered multitude, and many different Ideas contained under one higher Idea; and again, one Idea knit together into a single whole and pervading many such wholes, and many Ideas, existing only in separation and isolation. This is the knowledge of classes which determines where they can have communion with one another and where not. (253d).

Also in this context, the stranger concludes that one can speak of what is not without attributing to it the Idea of non-existence, because non-existence results from participation of something in the Idea of the different (to thateron), so that, what is different may not be one thing but it is still something and not nothing. One can say that a thing is not another thing but mean by this that it is different from that other thing. To be different requires a thing's participation in the Idea of the different. In this way, things can be said to have non-being. The stranger says,

But we have not only pointed out that things which do not exist (ta mê onta), do exist, but we have even shown what the Idea (eidos) of not-being is; for we have pointed out that the nature of the different exists (tên gar thaterou phusin apodeixantes ousan) and is distributed in small bits [258e] throughout all existing things in their relations to one another, and we have ventured to say that each part of the different that is contrasted with being really is exactly not-being (to mê on). (258 d-e)

The stranger then explains further that all things participate in the Ideas of Being (to on) and the Different (thateron) and each of these participates in the other. The result of this mutual participation of the two Ideas in each other is, first, that the Idea of the Different is because it participates in the Idea of Being, but is not Being because it is the Different, so that inevitably it is a thing that is not (heteron de tou ontos on esti' saphestata ex anagkês einai mê on). Thus, when a thing insofar as it participates in the Idea of the Different is contrasted with another thing, because of its participation in the Idea of the Different, it can be said not to be the other thing. Second, because of its participation in the Idea of the Different, the Idea of Being is different from and, therefore, is not all the other things that participate in it as an Idea. Socrates says, "And since it is other than all of them, it is not each one of them or all the rest, but only itself. There is therefore no doubt that there are thousands and thousands of things which being is not, and just so all other things, both individually and collectively, in many relations are, and in many are not" (259b). Because of its participation in the Idea of the Different, Being (to on) is not any of the thousand upon thousands of things that participate in it as an Idea, but is itself. These myriad of things both are and are not, each thing is what it is but is not what is different from it. In other words, in a sense, the Idea of the Different functions to differentiate Being from itself. The Idea of Being causes things to be, and the Idea of the Different causes things to be different from other things and different from Being, but to be what they are. (Sophist 257e - 259b)

    The stranger then examines the nature of language to complete his justification for the possibility of saying that what is not, is (260a-264b). A proposition consists of a subject and a predicate; judgment is the affirmation of truth or falsehood to a proposition. False propositions result when one (or more than one) Idea is said to be mixed with another Idea or an individual thing (i.e., proper name), when they are not so blended or blendable. This allows for the definition of the Sophist as a type of illusionist: one wrongly attributes the Idea of wisdom to the Idea of the subject of Sophist; these forms are not blendable.

4.6. Philebus (13e-18e)

In the dialogue Philebus, Socrates is in dialogue with a certain Protarchus concerning the question that Socrates and Philebus have been discussing, namely whether the good for all consists of pleasure or wisdom. The dialogue begins with Philebus having bowed out of the conversation and with Protarchus taking his place. Socrates makes an significant, but rather obscure digression in the dialogue concerning how and whether there could be a plurality and difference in knowledge (epistêmê), which is part of the larger question of how the one (to hen) can be many and the many (ta polla) one. He intends to investigate how it is possible to use abstract nouns like "man" or "the beautiful" as if these were each a "one," or a unity (monas), but also apply each abstract noun to a plurality of things. Socrates says,

The first question is whether we should believe that such unities really exist; the second, how these unities, each of which is one, always the same, and admitting neither generation nor destruction, can nevertheless be permanently this one unity; and the third, how in the infinite number of things which come into being this unity, whether we are to assume that it is dispersed and has become many, or that it is entirely separated from itself—which would seem to be the most impossible notion of all being the same and one, is to be at the same time in one and in many.

Socrates identifies three questions concerning these "unities." First, he seeks to know whether these "unities" really exist or whether such abstract terms have merely nominal existence and should not be mistaken are real entities. Assuming that these unities do exist and are not mere abstractions, what needs to be determined is how each of these unities can remain one, when the many that are also the one come in and go out of being. In other words, Socrates asks how each of these eternal unities can manifest itself as many instances of itself, coming into being and perishing, and still be itself as eternally one. The third question concerns the mechanism whereby the one becomes many. Is the one somehow dispersed to become the many or does it retain its oneness, so that the same unity is found in the one and the many.

    In order to answer these questions, Socrates proposes a method that he claims has been handed down from antiquity, indeed a gift from the gods: "That all the things which are ever said to exist are sprung from one and many and have inherent in them the finite (peiras) and the indefinite (apeiria)" (16 c-d). What follows is somewhat obscure but he seems to mean that any given thing as an individual is indefinite insofar as an individual thing it is not identified according to its participation in one of the unities or Ideas. Methodologically, one should search for the unity, the single Idea (mia idea) that gives unity to the thing; this is its limit. As Socrates says, "We must always assume that there is in every case one idea of everything [mia idea peri pantos] and must look for it—for we shall find that it is there" (16d). Having discovered that single Idea, however, one then searches for its other Ideas, which, though not defining the thing, nevertheless, removes it from its status as indefinite: "And if we get a grasp of this, we must look next for two, if there be two, and if not, for three or some other number; and again we must treat each of those units in the same way, until we can see not only that the original unit is one and many and infinite, but just how many it is" (16d). It seems that the goal is to enumerate exactly how many other Ideas there are, so that the thing's definiteness can be numbered. A thing is indefinite as an individual thing, but when one identifies the one Idea of the thing and the other Ideas belonging to it one has understood that thing, so that it is no longer indefinite. Merely to understand the one Idea is adequate to a complete understanding of the thing, because it is more than that one Idea. In other words, even though a thing is something by virtue of one Idea, and as such has a unity, nevertheless, the same individual thing has other characteristics or participates in other Ideas in addition to the one essential or defining Idea; these are subordinate and non-essential Ideas, but Ideas nonetheless. Moreover, these other Ideas will exist as a hierarchy of Ideas from the more general to the less general. For example, a man is such by virtue of the the Idea of manhood, but each individual man has numerous other characteristics implied necessarily in the idea of manhood: a man must be so tall, of a certain race, be so old, and so on. These further characteristics will be mutually exclusive: either a man is tall or short. Not only must one determine the limit or one defining Idea of a thing, but one must enumerate its other Ideas that further define the thing as a certain type of the thing identified in the one Idea. Beyond the lowest level of further classification implicit in the one Idea lies the individual as individual, or the indefinite or undefined. As Socrates obscurely expresses it, "And we must not apply the idea of indefinite to plurality until we have a view of its whole number between indefinite and one; then, and not before, we may let each unit of everything pass on unhindered into indefiniteness" (16d-e). The example provided by Socrates confirms this interpretation: sound is one but necessarily many. Sound is what it is by virtue of the Idea of sound, but implied in the Idea of sound are many other Ideas, because, for example, a sound is necessarily a certain pitch, somewhere between high and low (17b-d) or a certain magnitude, between loud and soft. In conclusion, Socrates issues this cautionary note, "The gods, then, as I said, handed down to us this mode of investigating, learning, and teaching one another; but the wise men of the present day make the one and the many too quickly or too slowly, in haphazard fashion, and they put infinity immediately after unity; they disregard all that lies between them (16e-17a).

    A confirmation of Plato's meaning concerning the limit and unlimited derives from the obvious Pythagorean influence on Plato in the Philebus. As explained by Aristotle, in Pythagoreanism, there exists the principle of the unlimited (or even), as a type of prime matter, without order or formal identity, co-eternal with which is the principle of the limited (or odd), which imposes order and formal identity on the unlimited (The unlimited is passive, whereas the limited is active) (Metaphysics, 986a 15-21; see also 987a 15). Read in light of its probable Pythagorean background, Plato's view seems to be that an individual thing in the sensible world is a combination of the limited and unlimited: from the absolute potentiality of the unlimited it has become limited or is a particular thing by virture of one Idea. But the individual thing stands between the limit and the unlimited because it is not simply the one Idea but necessarily numerous other, subordinate and hierarchically arranged Ideas, although these do not define it.

4.6. Important References to Plato's Teaching About Ideas in Aristotle's Works

4.6.1.  Eudemian Ethics

In Eudemian Ethics 1217b, Aristotle provides a summary of Plato's doctrine of the Idea of the Good the elements of which can be found in Republic.  In discussing Plato's doctrine of the Good, Aristotle further reveals that Plato and his school hold that the Good is also the One or Unity.  In addition, it seems that Plato teaches that all things are somehow drawn to the Good.  (Eudemian Ethics 1217b-1218a)

4.6.2. Metaphysics

Some of the summary of Plato's view in Metaphysics 1.6 is familiar to the reader of Republic.  Of special interest is that Plato is supposed to have taught that the Ideas are the cause of all things and the One, which Aristotle says elsewhere is identical to the Good, is the cause of the Ideas.  Aristotle gives evidence, however, that Plato had incorporated some Pythagorean elements into his philosophy, which are mostly absent from his dialogues. It is possible that these represented an esoteric teaching addressed only to the initiates of his school. Although it is difficult to reconstruct Plato's views owing to the brevity of Aristotle's account, it seems that Plato's One is similar to the Pythagorean Monad, from which comes numbers by the participation of the great and the small in the One. Also he claims that Plato says that the Ideas are numbers and that the dyad is matter in which the Ideas (as numbers) inhere. Aristotle enumerates more similarities and differences between Plato and the Pythagoreans, which are difficult to understand. (Metaphysics 1.6) (see also Metaphysics 1.9; 988a 10-11; Books 13, 14; Physics 1.9).

5. Cosmology in Timaeus

Although in all of his dialogues he touches upon cosmology, Timaeus is Plato's explicit attempt to to present his understanding of the origin and nature of the cosmos; it was very influential in the ancient world and remained well beyond that time period.  After relating a story about the ancient Athenians and the island of Atlantis, Timaeus takes up the task of explaining the origin and nature of the universe, by which he means the totality of created and corporeal existence.

5.1. The Probability of the Account of the Origin and Nature of the Cosmos

Timaeus, who, in the dialogue, represents Plato's views, says that, in setting forth his cosmology, he is operating in the realm of the probable only. (Timaeus 29b - d)  Plato believes that one can only speak truly of  the changeless and intelligible realm, "the eternal things themselves."  The reason for this is that only with respect to the eternal, the originals that are used as prototypes of things in the realm of becoming, words are used univocally:  they correspond exactly to the unchanging realities to which they refer.  When used to point to things in the realm of becoming, however, words used originally and primarily of the eternal things can have only an analogous sense.  For example, a beautiful flower is analogous to absolute beauty.  The realm of becoming is partially the realm of the unintelligible; it is the distinction made between knowledge and opinion set forth in Republic 5.  Thus, since he is dealing with the realm of becoming, Timaeus says that his hearers  must be content with opinion and probability, since words used originally and primarily of the eternal things only partially apply to things that are becoming.  They are not to be surprised to discover that the account has inconsistencies.  Timaeus reiterates that his account is only probable, and cautions his hearers that he is not to be taken as making dogmatic pronouncements (see Timaeus 48 c -e). Later in the dialogue, he again contrasts the "meditations about eternal things" with a consideration of the "truths of generation which are probable only."  (Timaeus 59 c - d)  The pursuit of former is, naturally, more important, but the occasional inquiry into the latter does provide a pleasurable diversion, even if one cannot attain to certainty.

Do you agree with Plato's theory of language?  Do words to be fully meaningful denote the Ideas, the eternal things?


5.2. The Destruction of Atlantis and the Original Athenians

The dialogue begins with the report from Critias that, when he was ten years old,  he heard a elderly man tell a story about Solon's conversations with an Egyptian priest; the priest said that Athens once led a united Mediterranean defense against invaders from Atlantis, defeating them. Afterwards, a flood and an earthquake destroyed both the Athenians and the whole island of Atlantis; the Egyptians survived and kept records of these events, whereas a new generation of Athenians emerged with no remembrance of their past and their relation with other peoples. This gives us a perspective on how some Greeks understood themselves in relation to other, more ancient cultures; there seems to have some embarrassment on the part of the Greeks for not being known as an ancient people. (Timaeus 20d - 27b)

5.3.  The Method of Creation

Timaeus sets out the well-known Platonic distinction  between the realm of the incorporeal, the eternal and being, which is apprehended by intelligence and  reason and that of the corporeal, the temporal and becoming, which is apprehended by opinion or sense perception. It is the distinction between, "What is that which always is and has no becoming; and what is that which is always becoming and never is" (27d). He further asserts that whatever is becoming must come into existence by some cause; the cosmos, therefore, since it is becoming, needs a creator. The realm of becoming is neither eternal nor self-caused, but was brought into being by the creator (dêmiourgos), the father of all; Timaeus cautions, however, that the creator is inscrutable:  "But the father and maker of this universe is past finding out, and even if we found him, to tell of him to men would be impossible" (28c). Because he is good, the creator made the cosmos after the pattern of the unchangeable and eternal:  "The world has been framed in the likeness of that which is apprehended by reason and mind and is unchangeable" (29a); thus the cosmos is a copy of the eternal and unchanging. (As will become clear, God did not create the universe ex nihilo.)  (Timaeus 27d-29c)

Is Plato's argument for the existence of a creator convincing?  Should this creator be considered inscrutable, as Plato affirms? Do you think that Plato's view that creator used the Ideas as the templates for creation makes sense?


5.4. The Process of Creation

According to Plato, God, the creator, took over that which was moving in irregular and disorderly fashion, and imposed on it regularity and order; this was done, as already indicated, by using the eternal things, the Ideas, as templates. He describes this process as the putting of a soul into the body of the universe, thereby putting intelligence (regularity and order)  into it. (Timaeus 29e-30c).  Into the center of the body of the universe, which is a sphere, God placed the soul, which is then diffused through the entire body and even envelopes it; the soul is to rule the body. This being is called a "blessed god."  Timaeus  describes the world soul as a third type of being created from "the being which is indivisible and unchangeable and from that kind of being which is distributed among bodies" (35a). He explains the process whereby the soul was created as follows: "And he made her out of the following elements and in this way: Out of the indivisible and unchangeable, and also out of that which is divisible and has to do with material bodies, he compounded a third and intermediate kind of being, partaking of the nature of the same and of the other, and this compound he placed accordingly in a mean between the indivisible, and the divisible and material. He took the three elements of the same, the other, and the being, and mingled them into one Idea (eidos), compressing by force the reluctant and unsociable nature of the other into the same" (34c-35a). In other words, the world soul is the combination of intermediate being with intermediate sameness and intermediate otherness or difference to form a composite; since the soul is composed not only of intermediate being, but also intermediate sameness and otherness or difference it can recognize sameness and otherness or difference in being in the world of generation and the world of eternal being as it encounters them. The world-soul is also said to be invisible, partaking of reason and harmony, and to be the best thing created. It is self-moving and turns in revolutions upon itself.

Does it make sense to speak of a world or cosmic soul?  Is this actually a mythopoeic conception?


5.5. The Cosmos as a Moving Image of Eternity

The creator desired to make the copy, the universe, as much like the original, the Ideas, as possible.  Since the latter is eternal, he attempted to make the former as eternal as possible.  Unfortunately, since the universe is not everlasting, the creator could only make the universe "a moving image of eternity." This means that he made part of the universe, the sphere of the heavens, move in predictable rotations, "moving according to number." It seems that, for Plato, time is the movement of the sphere of heaven; time comes into existence with motion or change. Circular motion stands closest to motionless eternity, because no permanent locomotion occurs, since that which is moving in a circle always returns to where it started. By the movement of the spheres, the becoming of the universe is measured, i.e., days, months, years etc. (Timaeus 37c - 38c)

5.6. The Cosmos as a All-Inclusive Creature

Timaeus explains that God made the cosmos after the likeness of  a living being that includes all other living beings: "The heavenly race of the gods; another, the race of birds whose way is in the air; the third, the watery species; and the fourth, the pedestrian and land creatures."  In other words, God created the cosmos after the Idea that includes all types of living beings. Since there is only one such Idea, there is only one cosmos. Because the cosmos is a copy of the one absolute Living Creature, the Ideas of all other creatures are to be found within it. The one universe is actually all beings at once.  (Timaeus 30c - 31b; 39e - 40a)

5.7.  The Third Type of Being

Timaeus says that there is another type of being than the indestructible and invisible Ideas and those things that perceptible objects that bear the names of the Ideas. This third type of being is unformed matter existing in space.  He calls this third thing, "the receptacle" and the "nurse of all becoming" (49b), and distinguishes this from "a pattern intelligible and always the same" and that which "was only an imitation of the pattern, generated and visible" (49a). Expressed differently, this third thing is a receiving principle that receives the Ideas and produces thereby an object of perception: "And we may liken the receiving principle to a mother, and the source or spring to a father, and the intermediate nature to a child." Although Timaeus calls this third thing "space," he does not mean that it empty space, but space filled with formless matter. This third thing is indestructible and eternal. Thus, it is this third thing that the creator took over and infused with soul and intelligence.  (Timaeus 48e - 52c)

Does Plato's view of space filled with formless matter make sense or is it a naive extrapolation of ordinary experience, i.e., an element of the world of common sense?


5.8.  Triangles

Within the formless matter of the receptacle, two types of triangles arise; these are the isosceles, which has only one form, and one particular type of the scalene triangle. The triangle is the first two-dimensional figure that can be created from points. These triangles combine in various ways to produce the four elements: earth, water, air and fire. The two-dimensional triangles become the three-dimensional elements. The elements, participating in the other Ideas, become all corporeal things. (Timaeus 53c - 55d)

5.9.  The Human Being

In Timaeus, the human being is one of the three classes of mortal beings created partially by the gods (which were created by the dêmiourgos and are visible—the stars and planets—and invisible) and partially by the dêmiourgos. The body, which is mortal, was created by the gods (cf. 42e-43a), whereas the soul was placed in the body directly by God; the soul is called the guiding principle and the divine part (41b-d). Individual souls are made out of the same stuff as the world soul, although it is explained that this stuff was not as pure as before (41d). Each soul was assigned a star (41d); if a person lived well, upon the death of the body the soul would return and dwell in his home star; if not, then the soul would be reincarnated (42a-c). Later in Timaeus, it is said that a human being has two souls, one immortal, created by the creator and one mortal, created by the gods, the offspring of the creator; the latter is subject to "terrible and irresistible affections" (69c). The mortal soul is placed in the breast and thorax, while the immortal soul inhabits the head. The mortal and inferior soul is subdivided into two parts occupying different parts of the body: "That part of the inferior soul which is endowed with courage and passion and loves contention, they placed nearer the head, midway between the midriff and the neck" (70a). This part of the mortal soul is allied with the immortal soul, which is to direct the other part of the inferior soul, the appetites, in check. (A similar statement of the tripartite view of the soul is found in Republic 4.)
Does Plato's view of the human being agree with your own?  If not, why not?


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