Existence - Historical Conceptions

Historical Conceptions

In the Western tradition of philosophy, the earliest known comprehensive treatments of the subject are from Plato's Phaedo, Republic, and Statesman and Aristotle's Metaphysics, though earlier fragmentary writing exists. Aristotle developed a comprehensive theory of being, according to which only individual things, called substances, fully have being, but other things such as relations, quantity, time, and place (called the categories) have a derivative kind of being, dependent on individual things. In Aristotle's Metaphysics, there are four causes of existence or change in nature: the material cause, the formal cause, the efficient cause, and the final cause.

The Neo-Platonists and some early Christian philosophers argued about whether existence had any reality except in the mind of God. Some taught that existence was a snare and a delusion, that the world, the flesh, and the devil existed only to tempt weak humankind away from God.

The medieval philosopher Thomas Aquinas, perhaps following the Islamic philosopher Avicenna, argued that God is pure being, and that in God essence and existence are the same. At about the same time, the nominalist philosopher William of Ockham argued, in Book I of his Summa Totius Logicae (Treatise on all Logic, written some time before 1327), that Categories are not a form of Being in their own right, but derivative on the existence of individuals.