 Although in Western philosophy the earliest formulation of a version of the cosmological argument is found in Plato’s Laws, 893–96, the classical argument is firmly rooted in Aristotle’s Physics (VIII, 4–6) and Metaphysics (XII, 1–6). Islamic philosophy enriches the tradition, developing two types of arguments. Arabic philosophers (falasifa), such as Ibn Sina (c. 980–1037), developed the argument from contingency, which was taken up by Thomas Aquinas (1225–74) in his Summa Theologica (I,q.2,a.3) and in his Summa Contra Gentiles (I, 13). Influenced by the Neoplatonist John Philoponus (5th c) (Davidson 1969), the mutakallimūm—theologians who used reason and argumentation to support their revealed Islamic beliefs—developed the temporal version of the argument from the impossibility of an infinite regress, now referred to as the kalām cosmological argument. For example, al-Ghāzāli (1058–1111) argued that everything that begins to exist requires a cause of its beginning. The world is composed of temporal phenomena preceded by other temporally-ordered phenomena. Since such a series of temporal phenomena cannot continue to infinity because an actual infinite is impossible, the world must have had a beginning and a cause of its existence, termed Allah or God (Craig 1979: part 1). This version of the cosmological argument entered the medieval Christian tradition through Bonaventure (1221–74) in his Sentences (II Sent. D.1,p.1,a.1,q.2).