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C H A P T E R  4


 P L A T O



(428/427 BCE – 348/347 BCE


Life of Plato


Plato went to Sicily after Socrates died.

Southern Italy was a part of Greece at the time.

In Sicily, he wrote most of the early dialogues, and the first half of the Republic.

He came back to Athens, and formed the Academy.

It was in a grove (academia).

He taught there until his death (age eighty).

His most noticeable student was Aristotle.

Aristotle stayed with Plato until Plato's death.

Aristotle formed the Lyceum.

He left Athens when the Macedonians started fighting again. Aristotle was a Macedonian.

His student was Alexander of Mascedon.


Plato wrote in the dialogue form.

He uses obviously fallacious arguments.

Socrates was consumed with social problems, moral problems, and political problems.

Plato was a metaphysician and epistemologist.

Plato doesn't take credit for his ideas.





  The Republic

Plato (427-347 B.C.)


Metaphysical/Epistemological Abstract


1.         Perceptions are unfit objects for knowledge.

           The following are true of perception:

               a.  Each man is the measure of all things (Protagoras).

               b.  All things change (Heraclitus).

               c.  They cannot be grasped by essential definitions (Socrates).


2.         Forms are proper objects of knowledge.

              a.  This knowledge is absolute and infallible.

              b.  Forms are eternal and unchanging (Parmenidies).

              c.  They exist apart from sensible things and God (Timaeus).

              d.  They are not in a place.

              e.  They are capable of essential definition (Socrates).


3.         The Good is the proper object of wisdom.




1.         a.            Sense knowledge is relative.


3.         God and the soul are Parmenidean (#380d, 381a)





The Good

unchanging, eternal

Higher Forms

Lower Forms


Intelligible Realm - Rationalism
objective, unchanging, eternal

Physical Objects


Shadows & Reflections   OPINION
Sensible Realm - Empiricism

particulars, spatiotemporal, changing, temporary

From the least real and least knowable
to the most real and most knowable.


Forms require images to understand them. These are things that are found in geometry, the human form (rational animal), or the form horse. These require our familiarity with particular circles, squares, people or horses. Beauty is an average. read  more


The higher forms don't require any images for us to understand them. These are found in the realm of pure mathematics. We cannot draw a picture of an algebraic equation or a differential equation? All the things philosophers concern themselves with would belong to this realm. The form of love, justice, beauty, goodness, and so on. 


The being of one depends on the other.

Reflections depend on the reflected object.

Material objects depend upon the forms they reflect.

A chair cannot be manufactured without a blueprint.

A photographer makes a brochure of the chair.

If you want to know the most real, you have to raise from the sensible to the intelligible.

In every field, we study general things - not particulars.


The senses lead to solipsism.

Reason concludes that this is an illusion.








The Republic

Plato (427-347 B.C.)


Political/Ethical Abstract

The # Represents Stephanas numbers from the Platonic Dialogues.


1.         Injury makes men unjust (#335).

2.         Justice is giving one's due (#335e).

3.         Justice is the interest of the strong (#338).
Advanced by Thrasymachus.
            Injustice is advantageous (#343) - Gyge's ring (#359).


                                     Rulers sometimes err. 

                                     Friends can be unjust to each other.

4.         Politics is directed towards the citizens.

5.         The soul contains reason, emotion, and desire.

6.         Justice (virtue) occurs when all three are harmonized (#442a).

7.         A state contains rulers, soldiers, and workers.

            Plato's Republic is totalitarian; everyone should not have a say.

            The worst form of government is a democracy.
8.         Justice (virtue) occurs when all three are harmonized.

            Its end is happiness (#353).

9.         Citizens should be educated, selected, and bred.

            Rulers are be educated as philosophers.

            It's a government of merit (meritocracy).  

10.       Personal property is abolished (Communism).





The Phaedo

Plato (427-347 B.C.)




1.         Forms are eternal and unchanging.

2.         The soul is eternal and unchanging.

3.         Knowledge is recollection.

            Knowledge is justified true belief.

4.         Physical things copy the forms. They are constantly changing.

5.         The forms are the proper objects of knowledge.

6.         The body is the cause of ignorance.

7.         Mind is the cause of all things (Anaxagoras).

8.         Be on guard for misology and misanthropy.



1.         A form is the true nature of a thing. A beautiful object is beautiful to the degree that it participates in absolute beauty. An act is just to the degree that it participates in absolute justice.


2.         Ideas like eternity, equality, perfection, and God could not have occurred to us in this lifetime, so we must have acquired them before we were born.

            The soul is colorless, formless, and intangible. Since the soul is the opposite of the body, there is no reason to think that they will share the same fate. The body is a composite thing. The soul is a simple thing.

            The soul is what brings life to the body.


3.         The forms cannot be known by the senses but by intuition.


4.            Physical things exist only to the extent that they copy their perfect, and eternal, patterns. We are reminded of the forms by the physical things that copy them.


6.         The forms are known by the mind alone. The body hinders the soul's search for knowledge (senses, desires, and emotions). Philosophers pursue death. They only seek necessary pleasures. True wisdom occurs after death.


7.         As a proof of the immortality of the soul, he says that all things are generated from their opposites. Mind is the opposite of all its contents. God created everything ex nihilo.


8.            Misology is caused by contributing you logical ineptness to reason. Misanthropy is caused by unrealistic expectations of people.



The dialogue was named after the narrator of the dialogue. Phaedo recounts the events, and the conversation, that took place between Socrates and his companions on the final day of his life. Two other main characters are Simmias and Cebes.







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