1. If the Universe “began to exist,” then it has a cause.1, 2, 3
2. The Universe “began to exist”.
3. Therefore, the Universe has a cause.
• Stanford Encyclopedia of Philosophy: “The standard view of the causal relata is that they are of the category of event, and that their number is two, in the roles of cause and effect. So on the standard view, when the cue ball knocks the nine ball into the corner pocket, there is said to be an (actual) event e1 of the cue ball striking the nine ball, and an (actual, distinct) event e2 of the nine ball sinking into the corner pocket, such that e1 is cause and e2 effect. The standard view, in short, holds that the causal relata are a pair of events.” [“The Metaphysics of Causation,” by Jonathan Schaffer, in The Stanford Encyclopedia of Philosophy (2014), online]
• Sidney Shoemaker: “It is events, rather than objects or properties, that are usually taken by philosophers to be the terms of the causal relationship.” [“Causality and properties” in Identify, Cause, and Mind (Oxford, 2003, 206.]
“But, wait. If every event has a cause, wouldn't a first supernatural event (e.g., the event of God's creating) require a cause?” [See response]1
Causation requires time (so you can't cause space-time to exist without it already existing). This is relevant because if causing space-time to exist is incoherent, then causing the universe (space-time) to exist is incoherent.
• …causation can be atemporal1