Philosophical Glossary

The school founded by Plato in Athens around 387 BC in a grove dedicated to the hero Akademos. The first institution of higher learning in the Western world, it lasted nearly 900 years until closed by Emperor Justinian in 529 AD.

Recollection or remembering. Plato's theory that learning is actually remembering what the soul knew before birth. The soul contemplated the Forms directly before entering the body; education is the process of recovering this forgotten knowledge.

State of puzzlement or impasse. Many early Socratic dialogues end in aporia — the interlocutors cannot define the concept they're discussing and recognize their ignorance. This perplexity is the beginning of philosophical inquiry.

Virtue, excellence, or goodness. The fulfillment of something's nature or function. Human arete includes both moral virtues (courage, justice) and intellectual virtues (wisdom). For Plato, arete is knowledge — to know the good is to do the good.

The art of philosophical conversation and reasoning. The highest form of knowledge, dialectic proceeds through question and answer to reach truth. Plato distinguishes it from eristic (arguing to win) and rhetoric (persuasion without truth). Methods include collection and division.

Discursive reasoning or understanding. The third level on the Divided Line, dianoia is the kind of thinking mathematicians use — working through proofs step by step, using hypotheses and diagrams. Higher than opinion but lower than pure intellection (noēsis).

Opinion or belief. Knowledge of the changing, visible world rather than eternal Forms. Doxa can be true by accident but lacks the stability and understanding of epistēmē (true knowledge). Most people live entirely in the realm of doxa.

Form, Idea, or pattern. The eternal, unchanging structures that constitute true reality. An eidos is not a physical object but an intelligible essence — the Form of Justice, Beauty, or Horse. Particulars participate in or imitate Forms. Central to Plato's metaphysics.

Imagination or conjecture. The lowest level of cognition on the Divided Line. Eikasia deals with images, shadows, and reflections — copies of copies. Those in the cave see only shadows and mistake them for reality.

Socratic method of refutation. Through questioning, Socrates exposes contradictions in his interlocutor's beliefs, leading them to recognize their ignorance. The elenchus is negative (shows what something is not) rather than positive (establishing what it is).

Knowledge or science. True, stable knowledge as opposed to mere opinion (doxa). Epistēmē is about unchanging objects (Forms), is justified, and involves understanding why something is true. Only philosophers who contemplate Forms achieve epistēmē.

Philosophical love or desire. In the Symposium, Diotima teaches that eros begins with attraction to beautiful bodies but can ascend through stages to love of Beauty Itself. Eros drives the soul upward from the visible to the intelligible realm.

Flourishing, happiness, or the good life. The ultimate goal of human existence. For Plato, eudaimonia comes from living justly (soul in harmony under reason's rule) and contemplating the Forms. Not pleasure but fulfillment of human nature.

Plato's central metaphysical doctrine: there exist eternal, unchanging, perfect patterns (Forms or Ideas) that are the true reality. Physical objects are mere copies or shadows of Forms. Knowledge is knowledge of Forms; opinion deals with the changing physical world.

The highest Form, source of being and knowability for all other Forms. Just as the sun illuminates visible things, the Good illuminates the intelligible realm. Plato calls it "beyond being in rank and power." To know the Good is the philosopher's ultimate achievement.

The ruling class in Plato's ideal city (kallipolis). Guardians are philosophers who know the Good and rule with wisdom. They live communally without private property or families to prevent corruption. Correspond to the rational part of the soul.

"Beautiful city" — the ideal state described in the Republic. Divided into three classes (rulers, auxiliaries, producers) corresponding to three parts of the soul. Justice is each class performing its proper function in harmony.

Reason, account, explanation, word, or rational principle. Can mean a reasoned argument, the faculty of reason itself, or simply speech. To give a logos is to explain rationally why something is true. Central to philosophical knowledge.

Imitation or representation. In Republic X, Plato argues that art is mimesis of physical objects, which are themselves mimesis of Forms. Thus art is "three removes from truth" and potentially misleading. This leads to his critique of poetry.

Education in music, poetry, and culture generally. One half of traditional Greek education (along with gymnastikē). In the Republic, Plato prescribes strict control of mousikē to ensure young guardians develop proper character.

Pure intellection or intuitive understanding. The highest level of cognition on the Divided Line. Noēsis is direct intellectual apprehension of Forms without reliance on sensory images or hypotheses. Achieved through dialectic after years of study.

Being, essence, or substance. What something truly is. Forms possess ousia fully and perfectly; physical objects have derivative being by participating in Forms. The Good is "beyond ousia" — transcendent even to being itself.

Education or formation of the whole person — intellectual, moral, and cultural. For Plato, true paideia is not filling an empty vessel but turning the soul from shadows to light, from becoming to being. The Republic is fundamentally a treatise on paideia.

Plato's controversial proposal: cities should be ruled by philosophers who know the Forms, especially the Good. Only those with knowledge can govern justly. Philosophers must return from contemplation to rule, though they would prefer to remain in study.

Belief or confidence. The third level from the bottom on the Divided Line. Pistis is belief about physical objects — higher than dealing with mere images but still in the realm of opinion rather than knowledge.

City-state. The fundamental political unit in ancient Greece. Athens, Sparta, Syracuse were all poleis (plural). For Greeks, the polis was not just government but the community that made the good life possible.

Soul or self. For Plato, the psychē has three parts: rational (logistikon), spirited (thymoeides), and appetitive (epithymētikon). The soul is immortal, existed before birth, and will exist after death. Philosophy is care of the soul.

The dialectical method of questioning used by Socrates (and Plato's Socrates). Through questions and answers, the interlocutor is led to recognize contradictions in their beliefs and thus their ignorance. The method is maieutic (midwifery) — helping others give birth to ideas.

Professional teacher of rhetoric and argumentation in ancient Greece. Plato (following Socrates) was highly critical of sophists, who taught persuasion without concern for truth and argued for money. Contrasted with philosophers who seek truth for its own sake.

The spirited part of the soul. Seat of emotion, especially anger, honor, and competitive drive. In a just soul, thumos allies with reason against appetite. In the ideal city, the auxiliaries (warriors) correspond to thumos.

Plato's division of the soul into three parts: rational (reason), spirited (emotion/honor), and appetitive (bodily desires). Justice is harmony among these parts with reason ruling. Parallel to the three classes in the ideal city.