AVICENNA'S ARGUMENTS FOR GOD'S EXISTENCE
1) Everything that exists either
(a) exists necessarily
or
(b) exists contingently.
(2) Everything that exists contingently has a reason or cause outside of itself that is responsible for its coming into being.
(This is the definition of "to exist contingently.")
(3) If the reason for something that exists contingently is also contingent, then either
(a) there is a further reason that is contingent, in a chain extending to infinity
or
(b) the chain culminates in a necessary being.
(4) If there were a chain of contingent beings extending to infinity, nothing would exist.
(Nothing that is contingent comes into existence except because of a reason.)
(5) There is something that exists contingently.
(Anything composite and material will do, such as a piece of paper.)
(6) Therefore, there is a necessary being.
(Question: From what premises above does this follow? Why does Avicenna see himself as entitled to the "Therefore"?)
(7) The necessary being is God.
(But is any necessary being necessarily God?)