Philosopher, Kant would agree with the quote and believes existence is not a predicate. You cannot talk about something and then state that it exists because we could do this with anything He gave the example of unicorns. Humans have an idea of what a unicorn is but this does not mean to say it exists just because we can picture what it could be like. Therefore in this example, we see through definition alone, God cannot be proved to be real because we could demand anything into existence but this does not mean it will happen.
Similarly, Hume argued that we cannot define something into existence. Just because we can think of a perfect form of it, it doesn’t mean it exists so again, Hume would agree with the quote and support the idea that God cannot be proved to exist simply through definition.
Gaunilo’s island supports Hume and Kant’s theory. He described the most perfect island with ‘beautiful sea and palm trees rustling in the wind’. He gave this ideal island to show that just because you can think about a perfect island in your mind, it does not mean it exists in reality.
Gods existence is not self-evident according to Aquinas. God requires empirical evidence which he offers in 1-5 of his ways of proving God’s being. He stated that we will never know if God just exists, we must prove is through his 5 ways. Due to God not being self-evident, we need proof to support the notion of His existence instead of defining Him into existence without evidence.
Russell’s supporting argument shows that we can talk about cows but not unicorns because we know that cows exist. This goes for God also. We can talk about things that are evident to us but we shouldn’t talk about things we cannot see.
Anselms argument however, opposes this greatly. He argued and said that if you accepted the ontological argument, then it would be unimaginable to believe that God exists. He says that God