According to Avicenna, whatever exists, while it exists, exists of necessity. Not all beings, however, exist with the same kind of necessity. Instead, they exist either necessarily per se or necessarily per aliud. Avicenna on the Necessity of the His Interpretation of Four Aristotelian Arguments explains how Avicenna uses these modal claims to show that God is the efficient as well as the final cause of an eternally existing cosmos. In particular, Celia Kathryn Hatherly shows how Avicenna uses four Aristotelian arguments to prove this very un-Aristotelian conclusion. These arguments include Aristotle's argument for the finitude of efficient causes in Metaphysics 2; his proof for the prime mover in the Physics and Metaphysics 12; his argument against the Megarians in Metaphysics 9; and his argument for the mutual entailment between the necessary and the eternal in De Caelo 1.12. Moreover, Hatherly contends, when Avicenna's versions of these arguments are correctly interpreted using his distinctive understanding of necessity and possibility, the objections raised against them by his contemporaries and modern scholars fail.
