Plato and Aristotle: Divergent Theories on Knowledge

Although Plato and Aristotle lived during the same time period, both philosophers developed two divergent theories of knowledge.

In order to define knowledge, Plato utilizes his dialogue Theaetetus, specifically a conversation had between Socrates and Theaetetus about knowledge, the divided line diagram, and the Allegory of the Cave. In the dialogue Theaetetus, Plato introduces the three definitions of knowledge as proposed by Theaetetus. He, Theaetetus, states at the prodding of Socrates that knowledge is perception [Aistheta ] or as expressed by Protagoras that “ man is the measure of all things”. Socrates rejects the first proposal stating that if man is the true measure of all things and his perception is infallible; thus making man the sole judge of what is right and wrong. If man is the sole judge, then there is no need for the teacher who claims that man is the measure of all things.

Theaetetus states that knowledge is true opinion. However, Socrates refutes this statement as well, affirming that to distinguish true from false opinion is impossible, if it is the opinion itself that is being used as the distinguishing factor. Theaetetus, then suggests that knowledge is true opinion with explanation. This definition is also rejected by Socrates, who argues that if the explanation is what makes the opinion true, then there is no need for the opinion .

With these rejected definitions in mind, Plato’s theory of knowledge, one that is grounded in idealism , calls for the separation of form and matter as well the existence of two worlds: the world of appearances and the world of intelligibly. The Platonic theory of knowledge states that knowledge is achieved through the ascension of, what Plato calls, the Plateaus of Kno...

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...be subjects whereas accidental things are limited to being only predicates . Substances are the “category proper to unqualified science” and answer the question “What is the thing in question?” .The nine accidents: Quantity, Quality, Relation, Place, Time, Situation, State, Action, and Passion, are used to classify the knowledge, basically the propositions about the aspects of things, provided first by experience and then by art.

Plato and Aristotle propose theories of knowledge in which they both agree that the knower is measure by the known and that knowledge is an exchange within the world. However, their respective theories may be considered polar opposites of one another especially when considering that Aristotle rejects Plato’s theory and admits that ‘informed opinion’, is a form of knowledge whereas Plato rejects opinion as a form of knowledge.