A Brief Proof of the Causal Principle

• If a thing begins to exist (that is, its essence becomes imparted with existence), then the potential that it has for existence is actualized.

• Nothing can actualize its own potential for existence, because things which do not (yet) exist are purely potential, and that which is purely potential cannot actualize anything. 

• So if a thing begins to exist, its potential for existence must be actualized by something apart from itself.

• So if something begins to exist, it must have an external cause of its existence.