Editing Cosmological argument (section)

=== Medieval Christian theology ===

[[Thomas Aquinas]] (c. 1225&nbsp;– 1274) adapted and enhanced the argument he found in his reading of Aristotle, Avicenna (the [[Proof of the Truthful]]) and [[Maimonides]] to formulate one of the most influential versions of the cosmological argument.<ref name=Aq5w>{{cite web|last1=Aquinas |first1=Thomas |url=https://www.newadvent.org/summa/1002.htm#article3|title=Summa Theologica: I Q2.3|website=New Advent}}</ref><ref>{{cite web|last1=Foutz|first1=Scott|url=https://www.quodlibet.net/aqu5ways.shtml|title=An Examination of Thomas Aquinas' Cosmological Arguments as found in the Five Ways|website=Quodlibet Online Journal of Christian Theology and Philosophy}}</ref> His conception of the first cause was the idea that the universe must be caused by something that is itself uncaused, which he claimed is 'that which we call God':<ref name=Aq5w/>

{{blockquote|The second way is from the nature of the efficient cause. In the world of sense we find there is an order of efficient causes. There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible. Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several, or only one. Now to take away the cause is to take away the effect. Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause. But if in efficient causes it is possible to go on to infinity, there will be no first efficient cause, neither will there be an ultimate effect, nor any intermediate efficient causes; all of which is plainly false. Therefore it is necessary to admit a first efficient cause, to which everyone gives the name of God.}}

Importantly, [[Five Ways (Aquinas)|Aquinas's Five Ways]], given the second question of his ''[[Summa Theologica]]'', are not the entirety of Aquinas's demonstration that the Christian God exists. The Five Ways form only the beginning of Aquinas's Treatise on the Divine Nature.