Objections to the Ontological argument:
Aquinas – rejected that there can be certainty that the human mind has the correct concept of God. He argues that God is beyond human understanding; therefore humans cannot prove that God exists from their mere idea. The existence is not self-evident. He continues to say that even if we have an inborn idea of god it is confused. Therefore a priori argument to prove god exists fails as we cannot define god.
Hume - argued that it is not possible to take an idea in one’s mind, apply pure logic to it and reach a conclusion based entirely in the external observable universe. He argued that existence cannot be treated as a predicate which something can have or not have, or which can be added or subtracted from something.
Kant – states that if we dismiss both the idea of the three sides and the idea of the triangle itself there is no contradiction. Therefore it is possible to dismiss the concept of God. Existence is not a predicate, saying x exists doesn’t tell us anything about x. According to Kant, a predicate must give information about X
Frege – First order predicate; tell us something about the nature of concepts and apply directly to object themselves…