Final answer:
Anselm's ontological argument for God's existence starts with defining God as the greatest conceivable being and uses a Reductio Ad Absurdum approach to prove that God must exist. It has faced criticism, particularly from Immanuel Kant, for its circular reasoning. In contrast, Samuel Clarke's Argument from Contingency offers an alternative cosmological argument for God's existence.
Step-by-step explanation:
Anselm's Ontological Argument for the Existence of God
St. Anselm, the Archbishop of Canterbury, put forth the ontological argument in the eleventh century, which is an a priori argument, aiming to prove the existence of God through reason and logic rather than empirical evidence. Anselm begins the argument with a definition of God as "a being than which nothing greater can be conceived." The premises he assumes in his argument are:
- The concept of God exists in the understanding as that than which nothing greater can be conceived.
- If God exists only in the mind, then a greater being can be conceived to exist in reality, which contradicts the definition of God.
- Therefore, God must exist in reality to be the greatest conceivable being.
This is a form of Reductio Ad Absurdum (RAA) where assuming the opposite (that God does not exist) leads to a contradiction, thus affirming that God must exist. However, this argument has been criticized for assuming what it is attempting to prove, making it circular. Moreover, the argument contends the existence of God is a necessary logical conclusion rather than contingent on sensory experience. Kant challenged Anselm’s argument, stating that existence is not a predicate that can increase the greatness of a being. In contrast, Samuel Clarke's Argument from Contingency is presented as a superior version of a cosmological argument, earning more acceptance than Anselm's ontological approach. His premises lead to a necessary being that underpins all contingent beings. According to Clarke, this necessary being is what we understand as God, which leads to a different conclusion of God's existence.