The Republic
Plato's ‘Republic’ contemplates conduct and the meaning of justice - whether the unjust man is happier than the unjust man.  Republic discusses two important Allegories: Allegory of the Cave and the Allegory of Charioteer. Also discussed is Plato’s theory of Forms or Ideas, the Ideal State and the philosopher’s role in society. 

The Republic is Plato’s plea that philosophy take over the role art played in Greek culture. The main concerns of Platonic philosophy were how to tackle the problem of knowledge or truth and the problem of conduct (goodness). Plato’s ‘ideals’ have origin in his Scala Naturae or 'The Great Chain of Being'.

The Problem of Knowledge: Allegory of the Cave

The problem of knowledge concerns the eternal conflict between the world of the senses and the world of Ideas.  The philosopher’s role is the mediator between the two.

In the Republic’s ‘Allegory of the Cave’ a group of people have been chained to a wall for all their lives. They only see images casted onto a blank wall.   The ‘philosopher’ is one who breaks free of his chains, ventures outside in the sunlit world to receive enlightenment, education and wisdom.
 • Being shackled is a metaphor for being a material object, being tied to a body.  Symbol of ignorance.  The sunlight is a metaphor for the guidance of the philosopher to the universal truth. Symbol of enlightenment or knowledge.
 • Seeing only a wall with shadows, the cave dwellers ascribe forms to them and interpret the shadows for reality. The shadows are taken for reality and the dwellers take their own passions and points of view for the only truth.
 • The only standard the shackled cave dwellers have is the Protagoras standard: “Each man is the measure of all things” (Protagoras was a pre-Socratic Greek sophist). Plato interprets the statement to mean that there is no objective truth.  Whatever individuals deem to be the truth, is true. What one sees is ‘real’.  The shackled does not have a standard that is external to or superior to the standard of his own experience or material-bound sense organs.  For the shackled reality is anything that anybody projects onto the wall.  He’s a puppet.  The hopeless dilemma of the sensualist.
 • The one who breaks his chains and climbs to the light – the ‘philosopher’ - is rejected by the cave dwellers who regard him as blinded and mad.  The philosopher’s truth is that the shackled are just puppets and are being terribly victimized.

The illustration below ties the “Allegory of the Cave” to the other allegories from Socrates and Plato: ‘Sun Simile’ and the ‘Divided Line’.  The world is divided into two realms: 1) the visible - the physical universe which we grasp with our senses, 2) the intelligible - the metaphyscial universe which we only grasp with our mind. Inspired by Socrates the 'Analogy of the Divided Line' is the cornerstone of Plato's metaphysical framework.  It illustrates the grand picture of Plato's metaphysics, epistemology and ethics all in one.

The Allegory of the Cave has other allusions: the death of Socrates and Plato having to deal with angry liberated cave prisoners who are upset at being freed from their illusions; the Noumenal-Phenomenal distinction; even the cave as the main principle in the movie 'The Matrix'.

The Problem of Conduct:  Allegory of Charioteer

 
The problem of conduct is the necessity of using rewards and punishment to get people to behave certain ways and to do certain things.

In the "Ring of Gyges", Book 2 of the 'Republic', the owner of the ring is granted the power to become invisible at will. Plato is exploring whether an intelligent person would be just if one did not have to fear any bad reputation for committing injustices. The myth of Gyges is a story how absolute power corrupts. The lure of the ring of invisibility hoodwinks the owner into believing that nothing of ethical consequence can follow – so it’s ok to kill the King, rape the Queen and take over the realm. Behavior similar to Ovid’s insolent god-like creatures. The spiritual upshot is that, in the end, there is compensation and retribution for all good and evil deeds done on Earth and that the soul knows the transgression, otherwise the owner is dark.

Plato’s “Ring of Gyges” inspired J.R.R. Tolkien’s 'Lord of the Rings'

In his dialogue ‘Phaedrus’ Plato uses the Chariot Allegory to explain the importance of rational power in one’s conduct.  The supremancy of reason – in terms of what we ought to do.

The Forms
The addition of the ‘Epistemology-Ontology’ perspective converts Plato’s one-dimensional ‘Divided Line’ is into a two-dimensional 4-Quad matrix:

The lowest level (Lower Left quad) represents ‘the world of becoming and passing away’.  The world of physical things themselves and their shadows and reflections. The illusion (eikasia) of our ordinary experience and the belief (pistis) about discrete physical objects which cast their shadows. The highest level (Upper Right quad) represents Plato’s Form that which is perfect, eternal and changeless, existing outside space and time.  Only the Forms are objects of knowledge, because only they possess the eternal unchanging truth that the mind - not the senses - must apprehend.  The Forms are eternal truths which are the source of all Reality.  In real life, beautiful things grow old and die.  The Form “Beauty” is eternal – it never dies.  For Plato to truly understand the Forms (Ideas) the philosopher must also understand the relations of Ideas to all the levels (‘quads’) to be able to know anything at all.

The concept that knowledge cannot be gained through sensory experience – Plato’s ideal of the Forms –  remerges in late European 17th-century rationalism begun by Descartes.  Likewise, the concept that knowledge can only be gained through sensory experience is seen in empiricism begun by Sir Francis Bacon.

American philosopher Ken Wilber’s AQAL framework has a similar structure to Plato’s ‘Worlds’ where the right planes or ‘quads’ represent the senses (the ‘exterior’) and the left quads represent ‘what we grasp with our minds’ (the ‘interior’). Wilber’s innovation includes an ‘Individual-Collective’ second dimension where the collective embraces attributes such as shared values, meanings, language, relationships, historicism and cultural backgrounds.

The Ideal State
The ethos of Greek society was that the Greeks debated various forms of government.  The ‘Republic’ discusses five types of regimes. 
The Greek poet Hesiod (c~700BC) lays out the five Ages of Man, known as the ‘Hesiodic myth’, in his work 'Work and Days'.  The myth is a convenient fiction that ranks man by the qualities and rarity of metal: “men of gold, silver, brass and iron” (each metal decreases in value and increases in hardness). Gold is the metaphor for those who cannot be corrupted (the so-called ‘Guardians’); bronze and iron is the metaphor for those who can be corrupted and whose existence is of toil and misery (ie, the ‘Producers’).
1) Aristocracy
Aristocracy is the form of government advocated in the ‘Republic’. The ideal society consists of three main classes of people (each with a ‘soul-type’ characterized by Plato). Each group must perform its appropriate function where justice is a principle of specialization: a principle that requires that each person fulfill the societal role to which nature fitted him and not interfere in any other business. Each person must remain in its class and must be in the right position of power in relation to the others. 
(1) “The Guardians” (‘men of gold’). The rulers whose minds are trained to grasp the Forms – the philosophers who are grounded on wisdom and reason all in the name of the ‘Form of the Good’. Soul-type: Rational.
(2) “The Auxiliaries” (‘men of silver’). The warriors who uphold the rulers’ convictions. Soul-type: Spirited.
(3) “The Producers” (‘men of bronze or iron’). Faming, blacksmithing, painting, etc. Soul-type: Appetitive (lusts after all sorts of things, but money most of all since money must be used to fulfill any other base desire).

The matrix below illustrates the comparison between Plato’s Aristocracy classes to Dr. Eric Berne's Transactional Analysis PAC model and the Three Levels of the Soul.

2) Timocracy
Timocracy is the government where only property owners may participate in government. A more advance form of timocracy is plutocracy - where the wealthy rule.
3) Oligarchy
A system of government where the wealthy are the administrators. A state of society where money is prized over virtue and the leaders of the state alter the laws to accommodate the materialistic lust of its citizens. Timocracy becomes an oligarchy.
4) Democracy
Where freedom is the supreme good, but freedom is also slavery. In democracy the lower class grows bigger and bigger, and the poor become the winners. People are free to do what they want and live how they want, even break the law if they choose.  Unchecked democracy (without ‘checks & balances’) can lead to anarchy.
5) Tyranny
Democracy degenerates into tyranny where no one has discipline and society exists in chaos. Power is seized by a tyrant to maintain order. The tyrant is typically difficult to remove once in office.

Socrates is asked, “Where are we going get them – these guardians of the state?”  He replies, “By giving birth to them. If they don’t measure up, we dispose of them, the State doesn’t need them”.  Dr. Daniel Robinson, professor of philosophy (Georgetown Univ), comments: “So explains Bertrand Russell’s ‘fascist’ interpretation…Plato proves not to be the happy-go-lucky, simple advocate of nude wrestling and exercise, but a much tougher - even a ruthless - advocate of the measure to insure the survival of the state” (in the contemporary university-state system the new reply appears to be, “If the students don’t measure up, we’ll make financial slaves of them”).

Socrates turns the table and asks the great question: “Can virtue be taught?” Professor Robinson continues, “Virtuosity is a 24/7 affair.  It is a universal principal – so it is not accessible to the senses. The senses can only pickup particulars, they cannot pickup universals. Teaching by showing, things you can touch, cannot be universals.  You can’t point at that which is universal.  How can you teach virtue if you can’t show something?, can’t point to it?...We can’t teach virtue in the empirical sense of pointing to virtue, but, perhaps, we can point to virtuous acts – to persons who act in a virtuous way.  A child will not understand by looking at acts of courage & heroism & sacrifice (women's suffrage); cannot work unless the audience is prepared...In Plato's Republic we have the foundations of an elitist position – who shall be virtuous? A convenient fiction of men of gold, of silver, of brass and of iron – the life of virtue is not available to anybody and everybody.  It takes a certain kind of person.”

In Closing
Is it better to be right? Is it better to achieve practical results? Is it better to understand? All these questions make up the fundamentals of rationality and empiricism. Is life truly how Plato explained it? (the ‘Chariot Allegory’ is a metaphor and metaphors have their limitations). Is life full of lies and false perceptions where one must use reason to see beyond it? Or is life like that of Hume or Aristotle where only perception can give you the true insight into reason?

Kant took these questions and composed a series of works that strove to quell the disparity between the two stations of thought (eg, the world of the 'Visible' and the 'Intelligible'). Kant formulated a world where humans are confined to their perceptions and that these perceptions help us to understand our world and are necessary for us to understand our ability to reason. Without reason there would be no way to explain what we perceive and without perception there would be no use to use reason for we would not have any questions. Every question we have today was presented through our perceptual experience.

Is it true that “nobody is born with innate knowledge”?  The idea that knowledge, ideas, and concepts including talents and skills are only learned from experience? Rationalism argues the idea that human beings have some universal knowledge, such as reasoning, mathematics, and ethics, which is then forgotten at birth and only uncovered by experience derived from the senses. Empiricism conveys the opposite idea, stating that our minds are blank slates from birth, with sensory experience providing the opportunity to deduce and reason more complex ideas.

Plato’s Allegory of the Cave argues that there is a possibility that what we are perceiving right now is actually false and we haven’t realized it yet. Descartes challenged empirical belief – the beliefs formed through our senses.