Plato's Philosophy: Ideas, Cosmology, and Politics

Plato's Core Ideas

Ideas and teachings from Heraclitus (movement and change) and Socrates (no one can define anything that changes) influenced Plato. Socrates and Parmenides presented a key dichotomy:

• Idea (Static): Each object known doubles (dynamic).
• Idea (Static): The essence of things.

The dialogos of maturity are difficult. The idea is extensive and is the essence of things. The world of things (sensible world) is separate from the world of ideas (intelligible world). The relationship between things and ideas involves participation and imitation. The idea of the good is the intermediary between idea and thing, the soul, aiding the sensible world. Ideas are also wise objects.

Cosmology

The universe has three characteristics:

1. Teleological Conception: A demiurge created the universe, using the ideas through the Nous (intellect) to fashion things.
2. Platonic Optimism: The sensible world is the best possible world; space is always the same.
3. Mathematization: The elements of the earth and sky (fixed stars) are related to polyhedra. The dodecahedron represents the sphere of fixed stars and the soul of the cosmos. Everything moves according to musical harmony.

The Human Being

The human being consists of soul and body. The soul is superior to the body. The soul has three parts:

• Rational
• Irascible (spirited)
• Appetitive

The rational part intends to approach the world of ideas. Metempsychosis (transmigration of souls) is involved. Reason must govern impulses, which must be discarded after death. The soul prepares for an immortal body.

Knowledge

Knowledge is reached through memory (anamnesis). We cannot know what we do not already know. The process ascends through hypotheses to the ultimate key. Two degrees of knowledge exist:

• Mutable belief (sensible/imaginable)
• Mathematical science (not merely showing, but defining)

Virtues and Love

Virtues are not innate; they arise from wisdom, which is purifying harmony. Love is the ascending process (noesis) starting from particular physical love (lust for the form of immortal beauty) to the love of the soul (which goes further than the personal) and culminating in the contemplation of the Idea of the Good (which is also the Idea of Beauty).

Politics

The ideal Polis is based on Justice. The Republic describes a just society requiring clear and just laws. Politics must overcome mere conception; it requires educating the citizens. Power belongs to the most intelligent.

Life and Works

Plato opposed the Sophists in his youth. His works are generally categorized by dialogue period:

• Youth Dialogues: Charmides, Laches, Crito, Socrates' Apology, Euthyphro.
• Early Dialogues: Ion.
• Transition Dialogues: Meno, Gorgias (known Pythagoreans).
• Mature Dialogues: Euthydemus, Cratylus, The Symposium.
• Major Dialogues: Phaedrus, The Republic.
• Critical Dialogues: Parmenides and The Sophist, Theaetetus.
• Later Dialogues: Philebus, Timeaus, Critias (fails again), Laws (teaches law again), Dionysius II (fails again in Athens).