 Scotus’s argument for the existence of God is rightly regarded as one of the most outstanding contributions ever made to natural theology. The argument is enormously complex, with several sub-arguments for almost every important conclusion, and I can only sketch it here. (Different versions of the proof are given at Lectura 1, d. 2, q. 1, nn. 38–135; Ordinatio 1, d. 2, q. 1, nn. 39–190; Reportatio 1, d. 2, q. 1; and De primo principio.)