is Averroes (ibn Rushd). The eastern group flourished from about the ninth to the twelfth centuries, while the western group, enjoying in Spain a culture vastly superior to that of medieval Christian Europe, arose about the tenth century and reached its height in the second half of the twelfth. For our purposes, however, there is a much more significant distinction within Muslim thought than that between eastern and western. Muslim thought on the cosmological argument may be divided into two schools,