John Duns Scotus (1266-1308), a medieval philosopher and theologian, made significant contributions to the discussion of the nature of God and the question of God’s unity. His argument for the unicity of God can be elaborated as follows:
Primacy of Divine Being: Scotus begins with the concept that God is the most perfect being and the source of all existence. In his view, God’s essence is absolutely unique and transcends any limitations or divisions. This understanding of divine perfection leads to the affirmation of God’s unity.
Infinite Being: Scotus argues that God’s perfection implies His infinite being. If there were multiple gods, each would possess an infinite nature, and this would result in a contradiction because no two infinite beings could coexist. Therefore, there can only be one infinite being, and that is God.
Indivisibility of Divine Attributes: Scotus contends that if there were multiple gods, they would need to be distinguished by their attributes or qualities. However, because God is perfect and indivisible, any attempt to differentiate gods based on attributes would result in a division within the divine essence, which is incompatible with the concept of God as a perfect, undivided being.
Simplicity of God: Scotus emphasizes the divine simplicity, which means that God’s essence is identical to His attributes. In other words, God’s wisdom, power, goodness, and all other attributes are one and the same as His essence. This unity in God’s attributes further supports the idea of His unicity.
One Ultimate Cause: Scotus argues that there can only be one ultimate cause of all things. If there were multiple gods, they would each claim to be the ultimate cause, leading to confusion and contradiction. To avoid this, there must be a single, supreme cause, which is God.
Scriptural and Theological Support: Scotus also draws upon theological and scriptural sources, particularly from Christian theology, to support his argument for the unicity of God. The Bible, for example, consistently presents God as one.
Scotus’ argument for the unicity of God is rooted in his understanding of divine perfection, infinity, simplicity, and the need for a single ultimate cause. It reflects his broader contributions to medieval scholastic philosophy and theology, where he engaged in complex debates about the nature of God and His attributes. This argument has had a lasting impact on the philosophy of religion and continues to be discussed and analyzed in contemporary philosophical and theological discourse.