Key Ideas in Plato's Philosophy

Dialectical Method

The dialectical method investigates the nature of truth through critical analysis of concepts and hypotheses. One of the earliest examples of this method is offered by the Greek philosopher Plato's Dialogues, in which the author undertakes the study of truth through discussion in the form of questions and answers. Plato's most famous student, Aristotle, understood dialectic as the search for the philosophical basis of science, and often used the term as synonymous with the science of logic.

The Idea of Good

The status and functions that Plato gives to the Idea of Good in his philosophy are such that many authors have identified it with God. This philosopher believed that the Idea of Good has two fundamental roles: it creates the ideas and the sensible world, and it gives intelligibility or rationality to both the ideas and the sensible world. The result is that all things (and especially men) aspire in one way or another to the Good. Philosophy is precisely the expression of the desire for ultimate understanding of that idea ("the ascent to being," says Plato). In the Myth of the Cave, the Idea of Good is represented by the metaphor of the Sun.

The Intelligible World

The Intelligible World, or World of Ideas, is populated by absolute, universal, independent, eternal, immutable entities that are beyond time and space. These entities are known by the most excellent part of the soul: the rational faculty. In this realm, the most valuable reality is the Idea of Good.

The Philosopher-King

The concept of the Philosopher-King appears as a consequence of two basic views on Plato's political philosophy: his authoritarian conception and his intellectual conception. Plato inherited from his teacher Socrates the idea that one cannot do good if there is no explicit knowledge of what is good.

Theory of Reminiscence

The theory of reminiscence is summarized in the idea that knowing is remembering. This theory complements the Socratic theory of knowledge and education: teaching is not to introduce knowledge into the mind of a subject, but to encourage the student to discover the truth within.

Plato's Concept of Opinion

Opinion is the title given by Plato to one of the forms of knowledge. This knowledge is based on perception, refers to the sensible world (i.e., spatio-temporal things, physical entities), and, in terms of knowledge level, is considered inferior.