The foundation of the oneness of God

The coherence of the concept of God is as important as the question of God's existence. Determining whether the existence of more than one God is possible is therefore an inevitable question for having a proper concept of God. In the introductory chapter, having provided a brief account of some conceptions of God that are related to the idea of Divine Oneness, I tackled with the epistemic ground, meaning and scope of the subject. In the first chapter, I examined a priori justification and arguments for God's Oneness based on concepts such as perfection, necessity, divine simplicity, and individuation. Here, I argued that the philosophical perspective which considers God in terms of "perfect being" provides a solid evidential ground for the justification of God's Oneness. In the second chapter, I mainly examined a posteriori reasons and arguments which mostly depend on the cosmological and teleological premises, that is, on God's power and causal activity on the realm of contingent beings. Also, I tried to clarify the intimate relation of these arguments to our a priori intuitions as deliniated in the first chapter. Under each heading, having evaluated the arguments for and against monotheism, I concluded that the truth of the Divine Oneness is rather a matter of conceptual necessity and that polytheism is therefore philosophically indefensible.