THE CAUSAL ARGUMENT FOR THE CONTINGENCY OF THE UNIVERSE
This argument seeks to prove the contingency of the universe using the principle of causality.
IMPORTANT DEFINITIONS FOR THIS ARGUMENT
Contingent being: A being which does not exist by neccesity of its own nature, and thus relies on external reasons for its existance.
Necessary being: A being whose existance is grounded in the necessity of its own nature; it is impossible for it to not exist, as its nature prevents it from being so.
The Universe: The natural world, time, space, matter, energy, and all natural processes such as quantum fluctuations, which we observe.
Strong Causality: Every state of the universe is wholly determined by the others.
Weak Causality: Every state of the universe is neither wholly determined nor wholly undetermined by the others.
Non-Causality: Every state of the universe is wholly undetermined by the others.
THE ARGUMENT
Premise 1: Either the universe obeys strong causality, weak causality, or non-causality.
This premise cannot be easily denied because I have partitioned off a clear trillema.
We have four options for the nature of causality in the universe: Fully determined and fully undetermined, fully determined and not fully undetermined, not fully determined and fully undetermined, and neither fully determined nor fully undetermined. The choice of "fully determined and fully undetermined" is a clear contradiction, therefore we are left with strong causality (fully determined, not fully undetermined), weak causality (neither fully determined nor fully undetermined), and non-causality (not fully determined and fully undetermined). This follows from the Law of Excluded Middle.
If the universe is fully determined, that means that every aspect of one state is fully determined by another state. So for example, if one state had a red ball in it, the next states would have a red ball in them. Or, if one state did not exist, then the next states would not exist either. So, every aspect of every state can be changed or removed by the other states.
If the universe is fully undetermined, that means that there is no aspect of one state determined at all by another state. So for example, if one state had a red ball in it, the next states could be literally anything because those states are not in causal relation with each other. If one state didn't exist, it wouldn't impact the other states at all. So, every aspect of every state is completely undetermined by the other states and are not in causal relation.
If the universe is neither fully undetermined nor fully determined, that means that some things are undetermined and some things aren't. Many argue that the universe is like this, with the arrangements in causal relation but the existance of the fundamental constituents is fixed; nothing in any state could stop the fundamental constituents from existing.
Premise 2: If the universe obeys strong causality or weak causality, it is contingent.
If the universe obeys strong causality, it means every state is completely contingent on the next. Even assuming that the universe is totally eternal (which contradicts modern cosmology) and therefore there are infinite states, the problem of infinite regress still applies: an infinite chain of non-reasons cannot come together to make an actual reason. Therefore, if strong casuality is true, the universe is contingent.
If the universe obeys weak causality, it means the arrangement of every state is completely contingent on the next. At this point, we must observe that the universe is a composite being, meaning it is composed of smaller parts. If all these parts were arranged such that none were in causal relation with each other anymore, the universe would seize to exist, even though the arrangement is the only thing that has changed. Even assuming that the universe is totally eternal (which contradicts modern cosmology) and therefore there are infinite states, the problem of infinite regress still applies: an infinite chain of non-reasons cannot come together to make an actual reason. Therefore, if weaak casuality is true, the universe is contingent.
Premise 3: The universe does not obey non-causality.
If the universe obeys non causality, it means that the arrangement and existance of every state is not dependent on the other states. This is clearly false; when I push a ball down a hill, it doesn't go down the hill because there are an incomprehensibly large set of causally independent states that just happened to assemble such that they create the illusion of causality; such a thing would be a massive violation of Occam's razor.
Conclusion: Therefore, the universe is contingent.
OBJECTIONS TO THE SECOND PREMISE
Why can't the arrangement of everything be contingent, but the arrangment of the universe as a composite object necessary?
Theoretically this is possible. However, we have no reason to think this, because this is a textbook case of special pleading: the person arguing applies a general principle to everything but exempts the universe for no reason.
What if we find a fundamental constituent that caused everything to be arranged the way it is? Maybe that's the necessary thing?
In order for us to find a fundamental constituent that caused everything, it would have to be irreducible to anything simpler and have caused everything. Furthermore, if we found it, it means that this thing is beyond space, time, and matter (which are reducible and contingent). In other words, not part of the universe, but a wholly other transcendent entity.