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Intro to Philosophy Unit 2: Ancient Philosophy: Socrates, Plato, Aristotle

Greek philosophy set the agenda for Western philosophy: what reality is made of, how we know it and how to live well. Socrates, Plato and Aristotle are the core figures, with the Presocratics before them and the Stoics and Epicureans after.

Covers: Presocratic philosophers, Socrates and the Socratic method, Plato's Forms and the Cave, Plato's Republic and the soul, Aristotle's metaphysics and four causes, Aristotle's virtue ethics, Stoics and Epicureans

Study guide

The Presocratics, working in the sixth and fifth centuries BCE, looked for natural explanations instead of myths. Thales said everything comes from water. Heraclitus stressed constant change, saying you cannot step into the same river twice, while Parmenides argued by pure reason that change is impossible because nothing can come from what is not. Democritus proposed that reality consists of tiny indivisible atoms moving in a void. Their debate about change and permanence shaped later philosophy. At the same time, the Sophists taught persuasive speaking for pay, and Protagoras claimed that 'man is the measure of all things,' a kind of relativism that Socrates and Plato opposed.

Socrates (469 to 399 BCE) wrote nothing; we know him mainly through Plato's dialogues. He questioned people who claimed to know what courage, piety or justice is, exposing contradictions in their definitions, a method called the elenchus. He said his only wisdom was knowing that he did not know. He held that virtue is knowledge and that no one does wrong willingly. Tried for impiety and corrupting the youth, he defended himself in the Apology, declaring that the unexamined life is not worth living. In the Crito he refused to escape, arguing he had agreed to obey Athens's laws. The Euthyphro poses the famous dilemma of whether the pious is loved by the gods because it is pious, or pious because it is loved.

Plato (about 428 to 348 BCE) argued that the changing world of the senses is less real than the Forms: perfect, eternal, nonphysical patterns such as Beauty, Equality and Justice, with the Form of the Good highest of all. In the Allegory of the Cave, prisoners mistake shadows for reality; the freed prisoner climbs into sunlight, as a philosopher rises to knowledge of the Forms. His theory of recollection says learning is remembering what the soul knew before birth. In the Republic, Plato divides the soul into reason, spirit and appetite, and defines justice as each part doing its proper work under reason's rule. The ideal city mirrors the soul, ruled by philosopher-kings.

Aristotle (384 to 322 BCE), Plato's student, brought forms down into things: every substance is a union of matter and form. To explain anything, he named four causes: material (what it is made of), formal (its structure), efficient (what produced it) and final (its purpose). In ethics, he argued that the highest human good is eudaimonia, flourishing, which is rational activity in accordance with virtue over a complete life. Moral virtues are habits formed by practice, each a mean between excess and deficiency, such as courage between cowardice and rashness, found by practical wisdom. After Aristotle, the Stoics taught that virtue is the only good and that we should accept what we cannot control, while Epicureans held that the good is pleasure, understood as tranquility and absence of pain.

Key ideas

• The Presocratics sought natural explanations of reality, debating change (Heraclitus) and permanence (Parmenides).
• Socrates questioned others to test definitions and claimed wisdom only in knowing his own ignorance.
• Plato held that the Forms are the truest realities and that the senses show only shifting appearances.
• Plato's tripartite soul (reason, spirit, appetite) grounds his definition of justice as inner harmony.
• Aristotle explained things through four causes and located form within particular substances.
• Aristotle's ethics aims at eudaimonia, achieved through virtues that are habitual means between extremes.
• Stoics prized virtue and acceptance of what is outside our control; Epicureans prized tranquil pleasure.

Formulas and rules

Common mistakes

• Thinking Plato's Forms are ideas in people's minds rather than mind-independent realities.
• Treating Aristotle's mean as an exact mathematical midpoint instead of what is right for the situation.
• Equating Epicurean pleasure with wild indulgence, when Epicurus favored simple living and tranquility.
• Assuming Socrates' views come from his own writings; he wrote nothing, and Plato is our main source.
• Confusing the final cause (purpose) with the efficient cause (what brought the thing about).

Before the test, make sure you can

• Identify the main claims of Thales, Heraclitus, Parmenides and Democritus.
• Describe the Socratic method and explain Socratic ignorance.
• Explain the Euthyphro dilemma and what it asks.
• Explain Plato's theory of Forms and interpret the Allegory of the Cave.
• Describe Plato's tripartite soul and his account of justice.
• Apply Aristotle's four causes to an example.
• Explain eudaimonia, the function argument and the doctrine of the mean.
• Contrast Stoic and Epicurean views of the good life.

Words to know

Presocratics

Early Greek thinkers, such as Thales, Heraclitus, Parmenides and Democritus, who sought natural explanations of the world.

Elenchus

Socrates' method of cross-examining someone's claims to reveal contradictions.

Socratic ignorance

Socrates' claim that his wisdom lay in knowing that he did not know.

Euthyphro dilemma

Is the pious loved by the gods because it is pious, or pious because the gods love it?

Forms

For Plato, perfect, eternal, nonphysical realities that physical things imitate.

Form of the Good

Plato's highest Form, which makes the other Forms knowable, compared to the sun.

Allegory of the Cave

Plato's story of prisoners who mistake shadows for reality, showing the ascent from appearance to knowledge.

Recollection (anamnesis)

Plato's theory that learning is remembering what the soul knew before birth.

Tripartite soul

Plato's division of the soul into reason, spirit and appetite.

Philosopher-king

In Plato's Republic, a ruler trained in philosophy who knows the Good.

Four causes

Aristotle's material, formal, efficient and final explanations of a thing.

Eudaimonia

Aristotle's term for flourishing, the highest human good.

Doctrine of the mean

Aristotle's view that each virtue lies between excess and deficiency.

Phronesis

Practical wisdom; for Aristotle, the ability to see the right action in a situation.

Stoicism

School (Zeno, Epictetus, Marcus Aurelius) holding that virtue is the only good and we should accept what we cannot control.

Epicureanism

School holding that pleasure, as absence of pain and mental disturbance, is the good.

Ataraxia

Tranquility or freedom from mental disturbance, the goal of Epicureans.

Sample practice questions

30 more questions like these, from level 1 to 5, are in the practice set.