Thomas R. Martin, An Overview of Classical Greek History from Mycenae to Alexander

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Platonic Forms

Plato refused to accept the relativity of the virtues as reality. He developed the theory that the virtues cannot be discovered through experience; rather, the virtues are absolutes that can be apprehended only by thought and that somehow exist independently of human existence. The separate realities of the pure virtues Plato referred to in some of his works as Forms¹ (sing. eidos , plur. eide , or sing. idea , plur. ideai ); among the Forms were Goodness, Justice, Beauty, and Equality. He argued that the Forms were invisible, invariable, and eternal entities located in a higher realm beyond the empirical world of human beings. The Forms such as Goodness, Justice, Beauty, and Equality are, according to Plato, true reality; what humans experience with their senses are the impure shadows of this reality.

Each Form, Plato seems to say, is an essential quality, one that people experience only through contrast between opposites. For example, that a stick embodies equality to another of the same length but inequality to a stick of a different length demonstrates equality only through contrast with the unequal stick. The Form Equality, however, is the pure essence of equality, which under no circumstances can be unequal or possess the quality of inequality. Such a pure Form is beyond human experience. The same reasoning applies to the other virtues such as goodness or beauty or justice.

Plato's concept of Forms required the further belief that knowledge of them came through the human soul, which must be immortal. When a soul is incarnated in its current body, it brings with it knowledge of the Forms. The soul then uses reason in argument and proof, not empirical observation through the senses, to recollect its pre-existent knowledge.

Plato was not consistent throughout his career in his views on the nature or the significance of Forms, and his later works seem quite divorced from the theory. Nevertheless, Forms provide a good example of both the complexity and the wide range of Platonic thought. With his theory of Forms, Plato made metaphysics a central issue for philosophers ever since.