On Proofs for the Existence of God: Aristotle, Avicenna, and Thomas Aquinas

In this paper, I examine Aristotle's cosmological proof of God's existence, Avicenna's metaphysical proof, and Thomas Aquinas's five-way proof. By comparing these proofs, I argue that philosophers and theologians take different approaches to proving God's existence not only because they follow different epistemological principles but, more fundamentally, because they construct different metaphysical frameworks in which God as the Supreme Being plays different roles and is thus clarified differently. The proof of God's existence is also of theological significance. This paper makes an original contribution by showing that, despite Avicenna's harsh criticism, Aquinas returns to Aristotelian cosmological proof. Moreover, Aquinas goes beyond Aristotle by identifying God not only as the First Mover but also as the Creator. The theme of God's existence bridges philosophy and theology, and it also clearly reflects the interplay and mutual influence of Greek philosophy, Arabic Aristotelianism, and Latin Scholastics.