Theory of Forms

Theory of Forms

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Plato
Plato
Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

's theory of Forms or theory of Ideas asserts that non-material abstract (but substantial
Ousia
Ousia is the Ancient Greek noun formed on the feminine present participle of ; it is analogous to the English participle being, and the modern philosophy adjectival ontic...

) forms (or ideas), and not the material world of change known to us through sensation
Allegory of the cave
The Allegory of the Cave—also known as the Analogy of the Cave, Plato's Cave, or the Parable of the Cave—is an allegory used by the Greek philosopher Plato in his work The Republic to illustrate "our nature in its education and want of education"...

, possess the highest and most fundamental kind of reality. When used in this sense, the word form is often capitalized. Plato speaks of these entities only through the characters (primarily Socrates) of his dialogues who sometimes suggest that these Forms are the only true objects of study that can provide us with genuine knowledge; thus even apart from the very controversial status of the theory, Plato's own views are much in doubt. Plato spoke of Forms in formulating a possible solution
Platonic realism
Platonic realism is a philosophical term usually used to refer to the idea of realism regarding the existence of universals or abstract objects after the Greek philosopher Plato , a student of Socrates. As universals were considered by Plato to be ideal forms, this stance is confusingly also called...

 to the problem of universals
Problem of universals
The problem of universals is an ancient problem in metaphysics about whether universals exist. Universals are general or abstract qualities, characteristics, properties, kinds or relations, such as being male/female, solid/liquid/gas or a certain colour, that can be predicated of individuals or...

.

Terminology: the Forms and the forms


The English word "form" may be used to translate two distinct concepts that concerned Plato—the outward "form" or appearance of something, and "Form" in a new, technical nature, that never
...assumes a form like that of any of the things which enter into her; ... But the forms which enter into and go out of her are the likenesses of real existences modelled after their patterns in a wonderful and inexplicable manner....
The objects that are seen, according to Plato
Plato
Plato , was a Classical Greek philosopher, mathematician, student of Socrates, writer of philosophical dialogues, and founder of the Academy in Athens, the first institution of higher learning in the Western world. Along with his mentor, Socrates, and his student, Aristotle, Plato helped to lay the...

, are not real, but literally mimic the real Forms. In the allegory of the cave
Allegory of the cave
The Allegory of the Cave—also known as the Analogy of the Cave, Plato's Cave, or the Parable of the Cave—is an allegory used by the Greek philosopher Plato in his work The Republic to illustrate "our nature in its education and want of education"...

 expressed in Republic, the things that are ordinarily perceived in the world are characterized as shadows of the real things, which are not perceived directly. That which the observer understands when he views the world mimics the archetype
Archetype
An archetype is a universally understood symbol or term or pattern of behavior, a prototype upon which others are copied, patterned, or emulated...

s of the many types and properties (that is, of universals
Universal (metaphysics)
In metaphysics, a universal is what particular things have in common, namely characteristics or qualities. In other words, universals are repeatable or recurrent entities that can be instantiated or exemplified by many particular things. For example, suppose there are two chairs in a room, each of...

) of things observed.

What are the Forms?


The Greek concept of form precedes the attested language and is represented by a number of words mainly having to do with vision: the sight or appearance of a thing. The main words, (eidos) and (idea) come from the Indo-European
Indo-European
Indo-European may refer to:* Indo-European languages** Aryan race, a 19th century and early 20th century term for those peoples who are the native speakers of Indo-European languages...

 root *weid-, "see". Both words are already there in the works of Homer
Homer
In the Western classical tradition Homer , is the author of the Iliad and the Odyssey, and is revered as the greatest ancient Greek epic poet. These epics lie at the beginning of the Western canon of literature, and have had an enormous influence on the history of literature.When he lived is...

, the earliest Greek literature. Equally ancient is μορφή (morphē), "shape", from an obscure root. The φαινόμενα (phainomena), "appearances", from φαίνω (phainō), "shine", Indo-European *bhā-, was a synonym.

These meanings remained the same over the centuries until the beginning of philosophy, when they became equivocal, acquiring additional specialized philosophic meanings. The pre-Socratic philosophers
Pre-Socratic philosophy
Pre-Socratic philosophy is Greek philosophy before Socrates . In Classical antiquity, the Presocratic philosophers were called physiologoi...

, starting with Thales
Thales
Thales of Miletus was a pre-Socratic Greek philosopher from Miletus in Asia Minor, and one of the Seven Sages of Greece. Many, most notably Aristotle, regard him as the first philosopher in the Greek tradition...

, noted that appearances change quite a bit and began to ask what the thing changing "really" is. The answer was substance
Substance theory
Substance theory, or substance attribute theory, is an ontological theory about objecthood, positing that a substance is distinct from its properties. A thing-in-itself is a property-bearer that must be distinguished from the properties it bears....

, which stands under the changes and is the actually existing thing being seen. The status of appearances now came into question. What is the form really and how is that related to substance?

Thus, the theory of matter and form (today's hylomorphism) was born. Starting with at least Plato and possibly germinal in some of the presocratics the forms were considered as being "in" something else, which Plato called nature (physis). The latter seemed as timber, ὕλη (hyle) in Greek
Greek language
Greek is an independent branch of the Indo-European family of languages. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. Its writing system has been the Greek alphabet for the majority of its history;...

, corresponding to materia in Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...

, from which the English word "matter
Matter (philosophy)
Matter is the substrate from which physical existence is derived, remaining more or less constant amid changes. anything that occupies space and has mass and weight...

" is derived, shaped by receiving (or exchanging) forms.

But what were the forms? In Plato's dialogues as well as in general speech there is a form for every object or quality in reality: forms of dogs, human beings, mountains, colors, courage, love, and goodness. Form answers the question "what is that?" Plato was going a step further and asking what Form itself is. He supposed that the object was essentially or "really" the Form and that the phenomena were mere shadows mimicking the Form; that is, momentary portrayals of the Form under different circumstances. The problem of universals - how can one thing in general be many things in particular - was solved by presuming that Form was a distinct singular thing but caused plural representations of itself in particular objects. Matter was considered particular in itself.

These Forms are the essences of various objects: they are that without which a thing would not be the kind of thing it is. For example, there are countless tables in the world but the Form of tableness is at the core; it is the essence of all of them. Plato's Socrates held that the world of Forms is transcendent to our own world (the world of substances) and also is the essential basis of reality. Super-ordinate to matter, Forms are the most pure of all things. Furthermore, he believed that true knowledge/intelligence is the ability to grasp the world of Forms with one's mind.

A Form is aspatial (transcendent to space) and atemporal (transcendent to time). Atemporal means that it does not exist within any time period, rather it provides the formal basis for time. It therefore formally grounds beginning, persisting and ending. It is neither eternal in the sense of existing forever or mortal, of limited duration. It exists transcendent to time altogether. Forms are aspatial in that they have no spatial dimensions, and thus no orientation in space, nor do they even (like the point) have a location. They are non-physical, but they are not in the mind. Forms are extra-mental (i.e. real in the strictest sense of the word).

A Form is an objective "blueprint" of perfection. The Forms are perfect themselves because they are unchanging. For example, say we have a triangle drawn on a blackboard. A triangle is a polygon with 3 sides. The triangle as it is on the blackboard is far from perfect. However, it is only the intelligibility of the Form "triangle" that allows us to know the drawing on the chalkboard is a triangle, and the Form "triangle" is perfect and unchanging. It is exactly the same whenever anyone chooses to consider it; however, the time is that of the observer and not of the triangle.

The Intelligible Realm and Separation of the Forms


Plato often invokes, particularly in the Phaedo
Phaedo
Plato's Phaedo is one of the great dialogues of his middle period, along with the Republic and the Symposium. The Phaedo, which depicts the death of Socrates, is also Plato's seventh and last dialogue to detail the philosopher's final days .In the dialogue, Socrates...

, Republic
and Phaedrus, poetic language to illustrate the mode in which the Forms are said to exist. Near the end of the Phaedo, for example, Plato describes the world of Forms as a pristine region of the physical universe located above the surface of the Earth (Phd. 109a-111c). In the Phaedrus the Forms are in a "place beyond heaven" (huperouranios topos) (Phdr. 247c ff); and in the Republic the sensible world is contrasted with the intelligible realm (noēton topon) in the famous allegory of the cave
Allegory of the cave
The Allegory of the Cave—also known as the Analogy of the Cave, Plato's Cave, or the Parable of the Cave—is an allegory used by the Greek philosopher Plato in his work The Republic to illustrate "our nature in its education and want of education"...

.

It would be a mistake to take Plato's imagery as positing the intelligible world as a literal physical space apart from this one. Plato emphasizes that the Forms are not beings that extend in space (or time), but subsist apart from any physical space whatsoever. That is, they are abstract objects. Thus we read in the Symposium of the Form of Beauty: "It is not anywhere in another thing, as in an animal, or in earth, or in heaven, or in anything else, but itself by itself with itself," (211b). And in the Timaeus Plato writes: "Since these things are so, we must agree that that which keeps its own form unchangingly, which has not been brought into being and is not destroyed, which neither receives into itself anything else from anywhere else, nor itself enters into anything anywhere, is one thing," (52a, emphasis added).

The ideal state


Socrates postulated a world of ideal Forms, which he admitted were impossible to know. Nevertheless he formulated a very specific description of that world, which did not match his metaphysical principles. Corresponding to the world of Forms is our world, that of the mimes, a corruption of the real one. This world was created by the Good according to the patterns of the Forms. Man's proper service to the Good is cooperation in the implementation of the ideal in the world of shadows; that is, in miming the Good.

To this end Plato wrote Republic detailing the proper imitation of the Good, despite his admission that Justice, Beauty, Courage, Temperance, etc., cannot be known. Apparently they can be known to some degree through the copies with great difficulty and to varying degrees by persons of varying ability.

The republic is a greater imitation of Justice:
Our aim in founding the state was not the disproportional happiness of any one class, but the greatest happiness of the whole; we thought that in a state ordered with a view to the good of the whole we should be most likely to find justice.


The key to not know how such a state might come into existence is the word "founding" (oikidzomen), which is used of colonization. It was customary in such instances to receive a constitution from an elected or appointed lawgiver; however in Athens, lawgivers were appointed to reform the constitution from time to time (for example, Draco, Solon
Solon
Solon was an Athenian statesman, lawmaker, and poet. He is remembered particularly for his efforts to legislate against political, economic and moral decline in archaic Athens...

). In speaking of reform, Socrates uses the word "purge" (diakathairountes) in the same sense that Forms exist purged of matter.

The purged society is a regulated one presided over by academics created by means of state education, who maintain three non-hereditary classes as required: the tradesmen (including merchants and professionals), the guardians (militia and police) and the philosophers (legislators, administrators and the philosopher-king). Class is assigned at the end of education, when the state sets individuals up in their occupation. Socrates expects class to be hereditary but he allows for mobility according to natural ability. The criteria for selection by the academics is ability to perceive forms (the analog of English "intelligence") and martial spirit as well as predisposition or aptitude.

The views of Socrates on the proper order of society are certainly contrary to Athenian values of the time and must have produced a shock effect, intentional or not, accounting for the animosity against him. For example, reproduction is much too important to be left in the hands of untrained individuals: "... the possession of women and the procreation of children ... will ... follow the general principle that friends have all things in common, ...." The family is therefore to be abolished and the children - whatever their parentage - to be raised by the appointed mentors of the state.

Their genetic fitness is to be monitored by the physicians: "... he (Asclepius
Asclepius
Asclepius is the God of Medicine and Healing in ancient Greek religion. Asclepius represents the healing aspect of the medical arts; his daughters are Hygieia , Iaso , Aceso , Aglæa/Ægle , and Panacea...

, a culture hero) did not want to lengthen out good-for-nothing lives, or have weak fathers begetting weaker sons - if a man was not able to live in the ordinary way he had no business to cure him ...." Physicians minister to the healthy rather than cure the sick: "... (Physicians) will minister to better natures, giving health both of soul and of body; but those who are diseased in their bodies they will leave to die, and the corrupt and incurable souls they will put an end to themselves." Nothing at all in Greek medicine so far as can be known supports the airy (in the Athenian view) propositions of Socrates. Yet it is hard to be sure of Socrates' real views considering that there are no works written by Socrates himself. There are two common ideas pertaining to the beliefs and character of Socrates: the first being the Mouthpiece Theory where writers use Socrates in dialogue as a mouthpiece to get their own views across. However, since most of what we know about Socrates comes from plays, most of the Platonic plays are accepted as the more accurate Socrates since Plato was a direct student of Socrates.

Many other principles of the ideal state are expressed: the activities of the populace are to be confined to their occupation and only one occupation is allowed (only the philosophers may be generalists). The citizens must not meddle in affairs that are not their business, such as legislation and administration (a hit at democracy). Wealth is to be allowed to the tradesmen only. The marketplace must not be regulated but left up to them. The guardians and the philosophers are not to own fine homes or cash reserves but receive a pension from the state. None of these items are consistent with an unknowable Good.

Perhaps the most important principle is that just as the Good must be supreme so must its image, the state, take precedence over individuals in everything. For example, guardians "... will have to be watched at every age in order that we may see whether they preserve their resolution and never, under the influence either of force or enchantment, forget or cast off their sense of duty to the state." This concept of requiring guardians of guardians perhaps suffers from the Third Man weakness (see below): guardians require guardians require guardians, ad infinitum. The ultimate trusty guardian is missing. Socrates does not hesitate to face governmental issues many later governors have found formidable: "Then if anyone at all is to have the privilege of lying, the rulers of the state should be the persons, and they ... may be allowed to lie for the public good."

Evidence of Forms


Plato's main evidence for the existence of Forms is intuitive
Intuition (knowledge)
Intuition is the ability to acquire knowledge without inference or the use of reason. "The word 'intuition' comes from the Latin word 'intueri', which is often roughly translated as meaning 'to look inside'’ or 'to contemplate'." Intuition provides us with beliefs that we cannot necessarily justify...

 only and is as follows.

The argument from human perception


We call both the sky and blue jeans by the same color: Blue. However, clearly a pair of jeans and the sky are not the same color; moreover, the wavelengths of light reflected by the sky at every location and all the millions of blue jeans in every state of fading constantly change, and yet we somehow have a consensus of the basic form Blueness as it applies to them. Says Plato:
But if the very nature of knowledge changes, at the time when the change occurs there will be no knowledge, and, according to this view, there will be no one to know and nothing to be known: but if that which knows and that which is known exist ever, and the beautiful and the good and every other thing also exist, then I do not think that they can resemble a process of flux, as we were just now supposing.

The argument from perfection


No one has ever seen a perfect
Perfection
Perfection is, broadly, a state of completeness and flawlessness.The term "perfection" is actually used to designate a range of diverse, if often kindred, concepts...

 circle, nor a perfectly straight line, yet everyone knows what a circle and a straight line are. Plato utilizes the tool-maker's blueprint as evidence that Forms are real:
... when a man has discovered the instrument which is naturally adapted to each work, he must express this natural form, and not others which he fancies, in the material ....


Perceived circles or lines are not exactly circular or straight, and true circles and lines could never be detected since by definition they are sets of infinitely small points. But if the perfect ones were not real, how could they direct the manufacturer?

Self-criticism


Plato was well aware of the limitations of the theory, as he offered his own criticisms of it in his dialogue Parmenides. There Socrates is portrayed as a young philosopher acting as junior counterfoil to aged Parmenides. To a certain extent it is tongue-in-cheek as the older Socrates will have solutions to some of the problems that are made to puzzle the younger.

The dialogue does present a very real difficulty with the Theory of Forms, which Plato most likely only viewed as problems for later thought. These criticisms were later emphasized by Aristotle in rejecting an independently existing world of Forms. It is worth noting that Aristotle was a pupil and then a junior colleague of Plato; it is entirely possible that the presentation of Parmenides "sets up" for Aristotle; that is, they agreed to disagree.

One difficulty lies in the conceptualization of the "participation" of an object in a form (or Form). The young Socrates conceives of his solution to the problem of the universals in another metaphor, which though wonderfully apt, remains to be elucidated:
Nay, but the idea may be like the day which is one and the same in many places at once, and yet continuous with itself; in this way each idea may be one and the same in all at the same time.


But exactly how is a Form like the day in being everywhere at once? The solution calls for a distinct form, in which the particular instances, which are not identical to the form, participate; i.e., the form is shared out somehow like the day to many places. The concept of "participate", represented in Greek by more than one word, is as obscure in Greek as it is in English. Plato hypothesized that distinctness meant existence as an independent being, thus opening himself up to the famous third man argument
Third Man Argument
The third man argument , first offered by Plato in his dialogue Parmenides, is a philosophical criticism of Plato's own theory of Forms...

 of Parmenides, which proves that forms cannot independently exist and be participated.

If universal and particulars - say man or greatness - all exist and are the same then the Form is not one but is multiple. If they are only like each other then they contain a form that is the same and others that are different. Thus if we presume that the Form and a particular are alike then there must be another, or third Form, man or greatness by possession of which they are alike. An infinite regress
Infinite regress
An infinite regress in a series of propositions arises if the truth of proposition P1 requires the support of proposition P2, the truth of proposition P2 requires the support of proposition P3, .....

ion would then result; that is, an endless series of third men. The ultimate participant, greatness, rendering the entire series great, is missing. Moreover, any Form is not unitary but is composed of infinite parts, none of which is the proper Form.

The young Socrates (some may say the young Plato) did not give up the Theory of Forms over the Third Man but took another tack, that the particulars do not exist as such. Whatever they are, they "mime" the Forms, appearing to be particulars. This is a clear dip into representationalism, that we cannot observe the objects as they are in themselves but only their representations. That view has the weakness that if only the mimes can be observed then the real Forms cannot be known at all and the observer can have no idea of what the representations are supposed to represent or that they are representations.

Socrates later answer would be that men already know the Forms because they were in the world of Forms before birth. The mimes only recall these Forms to memory. Science
Science
Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe...

 would certainly reject the unverifiable and in ancient times investigative men such as Aristotle mistrusted the whole idea. The comedian Aristophanes
Aristophanes
Aristophanes , son of Philippus, of the deme Cydathenaus, was a comic playwright of ancient Athens. Eleven of his forty plays survive virtually complete...

 wrote a play, the Clouds
The Clouds
The Clouds is a comedy written by the celebrated playwright Aristophanes lampooning intellectual fashions in classical Athens. It was originally produced at the City Dionysia in 423 BC and it was not well received, coming last of the three plays competing at the festival that year. It was revised...

, poking fun of Socrates with his head in the clouds.

Aristotelian criticism


The topic of Aristotle's criticism of Plato's Theory of Forms is a large one and continues to expand. Rather than quote Plato, Aristotle often summarized. Classical commentaries thus recommended Aristotle as an introduction to Plato. As a historian of prior thought, Aristotle was invaluable, however this was secondary his own dialectic and in some cases he treats purported implications as if Plato had actually mentioned them, or even defended them. In examining Aristotle's criticism of The Forms, it is helpful to understand Aristotle's own hylomorphic forms, by which he intends to salvage much of Plato's theory.

In the summary passage quoted above Plato distinguishes between real and non-real "existing things", where the latter term is used of substance. The figures, which the artificer places in the gold, are not substance, but gold is. Aristotle, stated that for Plato, all things studied by the sciences have Form and asserted that Plato considered only substance to have Form. Uncharitably, this leads him to a something like a contradiction: Forms existing as the objects of science, but not-existing as non-substance. Ross objects to this as a mischaracterization of Plato.

Plato did not claim to know where the line between Form and non-Form is to be drawn. As Cornford points out, those things about which the young Socrates (and Plato) asserted "I have often been puzzled about these things" (in reference to Man, Fire and Water), appear as Forms in later works. However, others do not, such as Hair, Mud, Dirt. Of these, Socrates is made to assert, "it would be too absurd to suppose that they have a Form."

Ross also objects to Aristotle's criticism that Form Otherness accounts for the differences between Forms and purportedly leads to contradictory forms: the Not-tall, the Not-beautiful, etc. That particulars participate in a Form is for Aristotle is much too vague to permit analysis. By one way in which he unpacks the concept, the Forms would cease to be of one essence due to any multiple participation. As Ross indicates, Plato didn't make that leap from "A is not B" to "A is Not-B." Otherness would only applies to its own particulars and not to those of other Forms. For example, there is no Form Not-Greek, only particulars of Form Otherness that somehow suppress Form Greek.

Regardless of whether Socrates meant the particulars of Otherness yield Not-Greek, Not-tall, Not-beautiful, etc., the particulars would operate specifically rather than generally, each somehow yielding only one exclusion.

Plato had postulated that we know Forms through a remembrance of the soul's past lives
Metempsychosis
Metempsychosis is a philosophical term in the Greek language referring to transmigration of the soul, especially its reincarnation after death. It is a doctrine popular among a number of Eastern religions such as Hinduism, Buddhism, Jainism and Druzism wherein an individual incarnates from one...

 and Aristotle's arguments against this treatment of epistemology are compelling. For Plato, particulars somehow do not exist, and, on the face of it, "that which is non-existent cannot be known". See Metaphysics
Metaphysics (Aristotle)
Metaphysics is one of the principal works of Aristotle and the first major work of the branch of philosophy with the same name. The principal subject is "being qua being", or being understood as being. It examines what can be asserted about anything that exists just because of its existence and...

III 3-4.

Dialogues that discuss Forms


The theory is presented in the following dialogues:
  • Meno
    Meno
    Meno is a Socratic dialogue written by Plato. It attempts to determine the definition of virtue, or arete, meaning virtue in general, rather than particular virtues, such as justice or temperance. The first part of the work is written in the Socratic dialectical style and Meno is reduced to...


    71-81, 85-86: The discovery (or "recollection") of knowledge as latent in the soul, pointing forward to the theory of Forms
  • Cratylus
    Cratylus (dialogue)
    Cratylus is the name of a dialogue by Plato. Most modern scholars agree that it was written mostly during Plato's so-called middle period...


    389-390: The archetype as used by craftsmen
    439-440: The problem of knowing the Forms.
  • Symposium
    Symposium (Plato)
    The Symposium is a philosophical text by Plato dated c. 385–380 BCE. It concerns itself at one level with the genesis, purpose and nature of love....


    210-211: The archetype of Beauty.
  • Phaedo
    Phaedo
    Plato's Phaedo is one of the great dialogues of his middle period, along with the Republic and the Symposium. The Phaedo, which depicts the death of Socrates, is also Plato's seventh and last dialogue to detail the philosopher's final days .In the dialogue, Socrates...


    73-80: The theory of recollection restated as knowledge of the Forms in soul before birth in the body.
    109-111: The myth of the afterlife.
  • Republic
    • Book III
      402-403: Education the pursuit of the Forms.
    • Book V
      472-483: Philosophy the love of the Forms. The philosopher-king must rule.
    • Books VI-VII
      500-517: Philosopher-guardians as students of the Beautiful and Just implement archetypical order.
Metaphor of the sun: The sun is to sight as Good is to understanding.
Allegory of the cave
Allegory of the cave
The Allegory of the Cave—also known as the Analogy of the Cave, Plato's Cave, or the Parable of the Cave—is an allegory used by the Greek philosopher Plato in his work The Republic to illustrate "our nature in its education and want of education"...

: The struggle to understand forms like men in cave guessing at shadows in firelight.
    • Books IX-X
      589-599: The ideal state and its citizens. Extensive treatise covering citizenship, government and society with suggestions for law
      Law
      Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

      s imitating the Good, the True
      Truth
      Truth has a variety of meanings, such as the state of being in accord with fact or reality. It can also mean having fidelity to an original or to a standard or ideal. In a common usage, it also means constancy or sincerity in action or character...

      , the Just, etc.
  • Phaedrus
    248-250: Reincarnation according to knowledge of the true
    265-266: The unity problem in thought and nature.
  • Parmenides
    129-135: Participatory solution of unity problem. Things partake of archetypal like and unlike, one and many, etc. The nature of the participation (Third man argument
    Third Man Argument
    The third man argument , first offered by Plato in his dialogue Parmenides, is a philosophical criticism of Plato's own theory of Forms...

    ). Forms not actually in the thing. The problem of their unknowability.
  • Theaetetus
    Theaetetus (dialogue)
    The Theaetetus is one of Plato's dialogues concerning the nature of knowledge. The framing of the dialogue begins when Euclides tells his friend Terpsion that he had written a book many years ago based on what Socrates had told him of a conversation he'd had with Theaetetus when Theaetetus was...


    184-186: Universals understood by mind and not perceived by senses.
  • Sophist
    Sophist (dialogue)
    The Sophist is a Platonic dialogue from the philosopher's late period, most likely written in 360 BCE. Having criticized his Theory of Forms in the Parmenides, Plato presents a new conception of the forms in the Sophist, more mundane and down-to-earth than its predecessor...


    246-248: True essence a Form. Effective solution to participation problem.
    251-259: The problem with being as a Form; if it is participatory then non-being must exist and be being.
  • Timaeus
    Timaeus (dialogue)
    Timaeus is one of Plato's dialogues, mostly in the form of a long monologue given by the title character, written circa 360 BC. The work puts forward speculation on the nature of the physical world and human beings. It is followed by the dialogue Critias.Speakers of the dialogue are Socrates,...


    27-52: The design of the universe, including numbers and physics. Some of its patterns. Definition of matter.
  • Philebus
    Philebus
    The Philebus , composed between 360 and 347 BC, is among the last of the late Socratic dialogues of the ancient Greek philosopher Plato. Socrates is the primary speaker in Philebus, unlike in the other late dialogues...


    14-18: Unity problem: one and many, parts and whole.
  • Seventh Letter
    342-345: The epistemology of Forms. The Seventh Letter is possibly spurious.

See also

  • Actual infinity
    Actual infinity
    Actual infinity is the idea that numbers, or some other type of mathematical object, can form an actual, completed totality; namely, a set. Hence, in the philosophy of mathematics, the abstraction of actual infinity involves the acceptance of infinite entities, such as the set of all natural...

  • Dunamis
    Dunamis
    In philosophy, Potentiality and Actuality are principles of a dichotomy which Aristotle used throughout his philosophical works to analyze motion, causality, ethics, and physiology in his Physics, Metaphysics, Ethics and De Anima .The concept of potentiality, in this context, generally refers to...

  • Energeia
  • Entelechy
  • Hexis
    Hexis
    Hexis is a Greek word, important in the philosophy of Aristotle, and because of this it has become a traditional word of philosophy. It stems from a verb related to possession or "having", and Jacob Klein, for example, translates it as "possession". It is more typically translated in modern texts...

  • Plotinus
    Plotinus
    Plotinus was a major philosopher of the ancient world. In his system of theory there are the three principles: the One, the Intellect, and the Soul. His teacher was Ammonius Saccas and he is of the Platonic tradition...

  • Potential infinity
  • Jungian archetypes
    Jungian archetypes
    Carl Jung created the archetypes which “are ancient or archaic images that derive from the collective unconscious” Also known as innate universal psychic dispositions that form the substrate from which the basic symbols or representations of unconscious experience emerge...

  • Dreamtime
    Dreamtime
    In the animist framework of Australian Aboriginal mythology, The Dreaming is a sacred era in which ancestral Totemic Spirit Beings formed The Creation.-The Dreaming of the Aboriginal times:...