Plato’s Theory of Ideas: Sensible and Intelligible Worlds

Posted on Jan 24, 2025 in Philosophy and ethics

The Intelligible World

Plato’s theory of ideas posits the existence of two distinct realms:

  • The Sensible World (SW): This is the world of our ordinary experience, perceived through the senses. It consists of a series of changing things and qualities, imperfect as they are born and die. In the Myth of the Cave, this realm is represented by the shadows on the cave wall.
  • The Intelligible World (IW): This realm consists of perfect, permanent, universal, and unique realities, not subject to birth and destruction. These are the true beings, such as Goodness itself, Justice itself, Beauty itself, etc. There is an idea for each series of things and qualities in the material world. These ideas are hierarchically organized, with the supreme idea of Good at the top. In the Myth of the Cave, this is represented by the world outside the cave.

The sensible world arises from the action of a Demiurge who shapes matter, modeled on the pre-existing intelligible world. Consequently, to capture the essence of the realities of the SW, one must know the realities of the IW, the Ideas.

The Idea of Good

  • The ideal realities are organized hierarchically, with the supreme idea of Good as the principle of being and intelligibility of all other ideas, and therefore, of all reality.
  • It is a univocal conception of Good: there is only one Good in itself. Other realities are good only insofar as they participate in Goodness itself.
  • In the Allegory of the Cave, the idea of Good is represented by the sun, which presides over the world outside the cave.

Methods of Inquiry and Types of Knowledge

Dialectics

  • As a method: Dialectics is a technique of investigation conducted through the collaboration of two or more persons in dialogue.
  • As a kind of knowledge:
    • Plato’s “theory of ideas” affirms the existence of two worlds, SW and IW. Each is subject to a kind of knowledge: sensible and intellectual.
    • There is a distinction between the intellectual knowledge of mathematical discursive reason and dialectics itself. Dialectics is the pure knowledge of ideas, connected hierarchically to the supreme idea of Good, the source of all reality and knowability.

Opinion

  • Sensible knowledge, or opinion, aims to capture the world of sense.
  • Plato distinguishes between two levels:
    • Imagination: The lowest grade, corresponding to seeing the shadows or images on the wall and believing these are real objects, including the only real ones.
    • Belief: To capture and correctly describe the objects and qualities of the physical world, although not being able to know their essence, as it is in the ideal world. In the Myth of the Cave, this degree of knowledge is represented by the prisoner freed from chains, who is able to look at objects directly illuminated by fire.

Reminiscence

  • The advancement of knowledge is remembering what our rational soul knew in a previous existence.
  • Humans are composed of a mortal material body and an immaterial, immortal soul (the rational soul).
  • The soul existed before in the world of ideas, from which it was driven into the world. During its existence in the world of ideas, it encountered ideal realities. Then, the soul was removed to the sensory world. When embodied, it forgets its previous existence and knowledge. Over time, it will remember the ideal realities, ideas, or models, the essence of the realities and qualities of the material world.

The Philosopher-King

  • Plato’s political theory was developed to combat Callicles’ thesis, which states that the strongest should govern the weakest and that what is natural is always good.
  • Plato agrees in part with Callicles (the best should govern) but argues that it should not be the strongest, but the wisest who govern.
  • In the ideal city, citizens are divided into three tiers according to the part of the soul that dominates them: workers, guardians, and governors. This ideal city is only possible if the wisest (the philosophers) govern, or if the rulers become philosophers.
  • Philosophers will not want to govern, but Plato proposes that they must be forced to return to society, as the wise should rule, in return for the effort the city made to educate and train them.