Plato's Theory of Forms: Influences, Hierarchy, and Philosophical Challenges

Plato's Theory of Ideas: Challenges and Structure

The dialogues Parmenides and Sophist review and question the Theory of Ideas, raising critical issues:

• What sorts of ideas are there? Must there be an idea for each common name?
• In addition to moral ideas, aesthetics, and mathematics, is there an idea for everything, even the ridiculous and the ugly?
• What are the relationships between ideas and things?

If the relationship is based on participation, the idea seems to lose its unity and transcendence. If it is imitation, that would imply a mutual similarity between the idea and the thing, which would lead to supposing another idea beyond both, and so on indefinitely (the Third Man Argument). Do the ideas maintain a relationship among themselves?

The Hierarchy of Ideas

In the Republic, Plato establishes a hierarchy whose head is the idea of property (or the Good), followed by the ethical, then the aesthetic, and finally mathematics. Plato maintains the concept of hierarchy in his works, but the supreme idea changes:

• In the Symposium, it is Beauty.
• In the Parmenides, it is The One.
• In the Sophist, Plato establishes Being, emphasizing the communication between Ideas without losing their own identity.

The Intellectual Landscape and Plato's Influences

The intellectual landscape was dominated by the failure of the philosophy of nature, which had shown the impossibility of constructing a science of the universal from rationality—at least a science that would be useful. Plato had attended discussions between Socrates and the Sophists and was aware of the risks posed by the relativism and skepticism of the latter to build a real episteme (true knowledge).

Incorporating External Ideas

Plato circumvents these difficulties by incorporating ideas drawn from others into his philosophy:

• From Heraclitus: Through Cratylus, one of his teachers, Plato agreed that there is a pluralistic, changing, and unstable world, witnessed by sensory awareness. For Plato, this sensory awareness was not true or valid knowledge.
• From the Pythagoreans: He considered their conceptual mathematical thinking as a precedent for his Theory of Ideas, recognizing the structure, mathematical relationships, and principles of intelligibility of the universe. He also adopted their conception of the immaterial and immortal soul.
• From Parmenides: Plato adopted rational knowledge as the true and valid means to reach the truth. He applied the nature of Being, as conceived by Parmenides, to the Ideas, which he considered the true reality.
• From Anaxagoras: Plato interpreted the Nous (Mind) as the intelligence responsible for the leadership and order of the cosmos.
• From the Atomists: Plato accepted the existence of eternal matter in constant, chaotic motion, though he rejected their explanation that order arises randomly from disorder.
• Shared with the Sophists: Plato shared the need to know human nature to understand peculiar human activity. However, he rejected Sophist skepticism regarding the possibility of such knowledge, their belief that strength and pleasure were basic features of human nature, and their view that Dialectic was pure rhetoric.
• From his teacher Socrates: Plato admired Socrates' attitude toward life in the search for truth. Socrates' death instilled in Plato the need to attain true knowledge of justice—one of the central Platonic ideas—to avoid arbitrariness and to demand fidelity to oneself and the city.

Athenian Cultural Ideals and the Search for Justice

The ideals of Athenian culture of the time—such as Harmony, Perfection, and Fees—also influenced him. Although convinced of the primacy of logos (reason), Plato used myth as an effective tool to explain his thinking.

Plato's search for the ideal of justice was not isolated; it mirrored contemporary cultural pursuits. For example, in sculpture, the research into the ideal of beauty is notable in works by artists like Polycleitus or Praxiteles. Their ideals were defined in terms of harmony, much like Plato defined justice or virtue. Moreover, the desire for truth was not solely linked to philosophical reflection in the 5th century B.C.E.