Plato’s Theory of Forms: Ideas, Opinion, and the Philosopher-King
Plato’s Theory of Forms
Dialectic
This concept has three different meanings in Plato’s work:
- Supreme science of Ideas and their relations, especially the relation of all Ideas to the Supreme Idea of the Good. It is the only path to true knowledge and the ultimate teaching for philosopher-kings. Plato attributed these characteristics to this type of knowledge:
- It is a cognitive activity, like the exercise of reason.
- Its subject is the knowledge of the intelligible world and the relationships between Ideas.
- Its ultimate aim is knowledge of the Idea of the Good as the ultimate foundation of all reality.
- Rational method identified with the practice of philosophy and science, providing reliable universal knowledge. It is a process of dialogue, questions, and answers seeking knowledge of Ideas—the truth or essence of things, reflected in their definition. This involves testing hypotheses through critical analysis and refutations, eliminating them one by one without resorting to sensory experience until reaching an assertion that resists all criticism. This is the ascending dialectic. A descending dialectic moves from the most general (Idea of the Good) to the concrete and particular, for application to the sensible and human world.
- Intellectual erotic impulse—an emotional and volitional love and aspiration for the Idea of the Good (Truth, Goodness, Beauty). This impulse guides the philosopher-king in daily activities, especially teaching.
The Idea of the Good
The supreme and most perfect Idea in the intelligible world. It encompasses all other Ideas and reflects the totality of reality. Knowing this Idea means possessing absolute truth and knowledge. It gives rise to all other Ideas and serves as a model for the Demiurge’s ordering of the sensible world. The Idea of the Good is the unifying principle that organizes and sorts the remaining Ideas, giving them intelligibility and rationality. Dialectic culminates in knowledge of the Good. All things, especially humanity, are drawn to the Good. Philosophy expresses this desire for ultimate understanding. The Idea of the Good is the foundation and cause of all reality and moral values, with virtue stemming from knowledge of it. Plato compared it to the Sun in the Myth of the Cave—the sun of Ideas, at the outer limits of the intelligible world, making true understanding possible and guiding ethical and political life.
Opinion (Doxa)
Superficial, unreliable, seemingly untrue, relative knowledge of the sensible world (changing, imperfect) derived from the senses, not intelligence. Plato distinguishes two levels:
- Imagination or conjecture (eikasia): images or shadows of sensory things (words, drawings, representations).
- Belief (pistis): things perceived directly (objects).
Plato considered opinion as between total ignorance and knowledge. In the Myth of the Cave, opinion is represented by the vision of things inside the cave. Opinion is opposed to knowledge, episteme—true knowledge of true reality, the eternal and unchanging essence of Ideas. It is universal and necessary knowledge of Ideas, attained through reason by the philosopher. Two levels exist:
- Discursive reasoning or thought (dianoia): knowledge of mathematical and geometric objects.
- Intuitive reasoning or intelligence (nous): knowledge of Ideas, especially the Idea of the Good.
The Philosopher-King
A political figure essential for a just society. In The Republic, philosopher-kings govern and educate other classes. Scholars and philosophers govern because they possess the right understanding of the intelligible world—pure and perfect forms (Ideas). They have a highly developed rational soul, balancing concupiscible and irascible souls (the Charioteer myth), and exhibiting the virtue of prudence or wisdom. Harmony among the three souls allows them to perceive the Idea of justice. Philosopher-kings aspire to the good of society, without personal ambition, living communally without family or private property. They undergo extensive education to be competent leaders.
The required disciplines progress from gymnastics and music to mathematics and dialectic. Future leaders deeply study the latter two, focusing on dialectic to attain knowledge of the Good. In the Myth of the Cave, the philosopher-king is the freed slave who, after seeing the sun (the intelligible world and the Idea of the Good), returns to liberate and govern his former colleagues. Plato’s utopian society includes two classes: producers (farmers, artisans, traders) responsible for material needs, whose primary soul is concupiscible, developing temperance; and defenders (soldiers) protecting the polis, whose primary soul is irascible, developing courage.
Reminiscence (Anamnesis)
The dialectical or intellectual process of remembering universal and necessary knowledge already present in the rational soul, a product of the intelligible world and the Idea of the Good. True knowledge requires knowing reality itself—the Ideas. How do we know these Ideas? Not through sense experience, which shows only the tangible world. We must focus on reason, which has direct access to the intelligible world. Reminiscence recalls Ideas hidden in the soul since birth. This process can be triggered by perceptions that cause the rational soul to seek the Ideas they represent, including art, music, aesthetic or religious ecstasy, and especially dialectic. Knowledge is possible because the rational soul inherently resides in the intelligible world, though embodiment in a body confuses it and causes it to forget the Idea of the Good. This knowledge is weakened but not lost. This theory complements the Socratic theory of knowledge and education: teaching is not introducing knowledge but encouraging students to discover the truth within. Plato illustrates this in the Meno dialogue, where an untrained slave, guided by the right questions, discovers mathematical truths like the Pythagorean theorem. The teacher’s role is to elicit these Ideas. Everyone can attain truth.
The Intelligible World
Plato posits two realities: the world of sense (physical, material, known through senses and experience; inside the cave in the Myth of the Cave) and the intelligible world (formal, ideal, known through reason; outside the cave). This is ontological dualism. The intelligible world of Ideas is true reality: immaterial, eternal, immutable, abstract, universal, independent of the physical world, perfect, intelligible, and ontologically existent. Ideas, though perfect, are the real causes of the sensible world (the Demiurge uses them to create objects). Reason grasps the Ideas’ essences, which are permanent and eternal. Ideas are models, archetypes of the sensible world; things are copies of Ideas. In the intelligible world, Ideas are hierarchically organized, with the Idea of the Good supreme (like the Sun in the sensible world). This is followed by moral Ideas, mathematical Ideas, and Ideas of natural things. While often used synonymously with the World of Ideas, the intelligible world also encompasses mathematical objects, which, though intangible, eternal, and immutable, represent a lower level of reality than Ideas. The sensible world or things represent false reality: sensory, changing, contingent, temporal, particular, imperfect, created, subject to birth and death. It includes the body and things perceived through the senses. Knowledge of it yields only opinions. Sensory images are shadows; we can only conjecture. Regarding things themselves (copies of Ideas), we have beliefs. The sensible world is ordered by the Demiurge in imitation of Ideas. Ideas are immanent in things.
The Soul
Plato advocates anthropological dualism, where humans are a composite of an immaterial, immortal soul and a material, mortal body. The soul gives life and is the source of knowledge, its proper function being knowledge of truth. Influenced by Pythagoreans, Plato believed the soul had a prior existence and seeks release from the body, its prison. Plato identified two souls dependent on the body and thus subject to death:
- Concupiscible soul (responsible for base passions, located in the liver; its virtue is temperance).
- Irascible soul (responsible for noble passions, located in the heart; its virtue is courage).
In the Charioteer myth, these souls are wild horses guided by the rational soul (responsible for knowledge, located in the head; its virtue is prudence or wisdom). This immortal soul survives the body and returns to the intelligible world. Harmony among the three souls produces a fourth virtue: justice, proper to the philosopher-king.