Plato
Above all else, it might be said that the defining subject of Metaphysics is Aristotle arriving at the point in his experiences when he had no choice but to reject Plato’s theories of Forms. The Platonic view toward metaphysics is that the universe can be neatly divided into two separate and distinct categories which allow for no overlapping. There exists the world of things which can be believed because they can be seen or heard or touched and there exists the world of ideas and thoughts. Ironically for modern sensibilities, Plato believed that it was only those things which could not be experienced with the senses that constituted authentic reality. Aristotle believed this as well for much of his life, but eventually broke and developed his metaphysical theories which insisted that Plato’s division resulted only an abyss devoid of real meaning.
Socrates
Before there was Aristotle, there was Plato and before Plato there was Socrates. What passes through Plato to Aristotle by definitely began—at least at some level—with Socrates. And what is the beginning level of any school of philosophical thought? “Seeking the whatness of a thing…seeking to prove something, and the whatness of a thing is a principle of syllogisms.” Socrates as a character is therefore most significant in relation to defining the principles of metaphysical theory.
Parmenides
Before Socrates, there was Parmenides. In fact, it is this pre-Socratic Greek philosopher upon whom is often conferred the title Father of Metaphysics. Aristotle singles him out for worthiness of study over his peers Xenophanes and Melissus primarily on the basis of suggesting—and really only suggesting—that Parmenides “seems to be saying something” with his theoretical construct that revolves around the rejection of Nonbeing as actually existing in opposition to Being.
Heraclitus
Another important pre-Socratic figure in the development of metaphysics is Heraclitus. He represents what Aristotle describes as one of the more extremes schools of thought on the matter and particularly takes him to task for his assertive rejection of the law of non-contradiction despite providing no explication for how this oppositional perspective might be valid. The law of non-contradiction is the famous dictum that if two propositions are forwarded which stand on contradiction to each other, logic dictates that it is impossible for them both to be true.
