I very much enjoyed this chapter from Groothuis' Christian Apologetics on cosmological arguments.
There are three: Principal of Sufficient Reason (Leibniz), Kalam Cosmological Argument (Muslim theologians, St. Bonaventure, WLC, etc.), and what I'd like to call the Non-eternal Heat Death Argument (cool YouTube video--what in the Sam Hill?!) that is part of the section on all the evidence of the Big Bang. The principal of sufficient reason stands whether or not the universe has a beginning and argues that God is a logically necessary being, whereas the Kalam argues that God is a factually necessary being and is dependent on there being a beginning to the universe, which is supported by logical evidence against an infinite regress, independent of the reigning cosmology. Various objections to everything I just mentioned are answered throughout the chapter.
Heidegger: "Why are there existents rather than nothing? That is the question. Clearly it is no ordinary question. 'Why are there existents, why is there anything at all, rather than nothing?'--obviously this is the first of all questions." (Groothuis uses existents instead of essents to convey a more straightforward meaning than the translation he was using.)
Leibniz: "The first question which should rightly be asked will be, Why is there something rather than nothing?" ...since nothing happens without a sufficient reason (PSR in a nutshell).
Answering two objections to cosmological arguments:
1. The first premise of the Kalam Cosmological Argument is NOT: "Everything that exists must have a cause." If that were so, then one could demand a cause of the First Cause. But, in actuality, the first premise of the Kalam Cosmological Argument IS: "Whatever BEGINS to exist has a cause." The First Cause does not have a beginning.
NOTE: The principle of sufficient reason stands even if there is no beginning--but still cannot be applied to God. The self-existent cause of all contingent causes is without need of a cause (which is neither to say that it is self-caused, nor "uncaused"--just self-existent...John 5:26, Acts 17:25). It is the stopping point.
NOTE: You may be wondering: If one left the premise as "Everything that exists must have a cause" and interpreted it to read like the Principle of Sufficient Reason (cause=explanation), couldn't one just answer: "God is self-existent" like you do with the PSR? The answer is "No. Because the Kalam Cosmological Argument is dependent on the universe having a beginning, whereas the Principle of Sufficient Reason is not--because they are two different arguments, and so their premises need to reflect that. If you change the wording of the Kalam Cosmological Argument so that it means the same as the PSR, you're getting away from the physical beginning of the universe and into a completely different argument." There is probably a less wordy way to phrase that answer.
2. Kant is wrong that cosmological arguments require the ontological argument's concept of God as a logically necessary being, which Kant attempted [falsely, Groothuis says in chapter 10: Kant's criticism that existence is not necessary to the idea of God (or that existence cannot function as a predicate for the subject of God) fails, because God is a possibly existing thing whose existence is a legitimate question (not all conclude he does exist)] to refute. The PSR concludes God is logically necessary, but not based on the Ontological Argument (that could've been stated more clearly in the chapter). And the Kalam Cosmological Argument (as most cosmological arguments do...) concludes God is factually necessary, not logically necessary--and not based on the Ontological Argument.
The Principle of Sufficient Reason
Basically, everything (entity, event, premise, etc.) has a complete explanation, including the universe--even if it has always existed.
Some naturalists object that even though all the parts of the universe require explanations outside themselves, the universe as a whole does not. Dr. Groothuis says this entails nihilism, a universe devoid of meaning, but we haven't gotten to the moral argument chapter (15) yet, so we won't yet go into the details of this or how naturalists get meaning.
Groothuis responds that "it seems arbitrary and ad hoc to search for explanations for anything and everything in the universe (as does science) but not to seek an explanation for the universe as a whole" (p. 213).
Some posit that the universe itself is a necessary being--a being that explains itself. Groothuis responds that "We can certainly conceive of the universe being different from what it is or of it not existing at all. Our question, Why is there something rather than nothing? pertains perfectly well to the universe." And he quotes Taylor saying "Concerning anything in the world, we have not the slightest difficulty in supposing that it should perish, or even that it should never have existed in the first place. We have almost as little difficulty in supposing this of the world itself" (p. 213).
Groothuis gives this modus tollens argument:
1. If God is not the sufficient explanation of the universe, then either a) it is no explanation, or b) it is self-explanatory.
2. The universe is not without explanation (which would entail nihilism).
3. The universe is not self-explanatory (pantheism).
4. Therefore, God is the sufficient explanation of the universe.
The Kalam Cosmological Argument (Dr. William Lane Craig's formulation)
1. Whatever begins to exist has a cause.
2. The universe began to exist.
3. Therefore, the universe has a cause.
... 4. The cause of the universe is God.
On the first premise:
That matter can be created from a state of zero energy is not the same as saying matter can arise from nothing (as some object). A state of zero energy, when positive and negative energy sum up to zero--is not "nothing"...to suggest otherwise is "the ontologizing of nothingness" (p. 216)--or giving being to nothingness.
John Jefferson Davis also answers those who think subatomic particles pop into existence out of nothing (and so think the universe could have, as well)--"Quantum-mechanical events may not have classically deterministic causes, but they are not thereby uncaused or acausal. The decay of a nucleus takes place in view of physical actualities and potentialities internal to itself, in relation to a spatiotemporal nexus governed by the laws of quantum mechanics. The fact that uranium atoms consistently decay into atoms of lead and other elements--and not into rabbits or frogs--shows that such events are not causal but take place within a causal nexus and lawlike structures" (p. 217).
On the second premise:
It is logically impossible that the universe is infinite, because if it were, we would never have reached the present moment--because--first of all, and easiest for me to comprehend: if you can arrive at a destination, your journey has been a finite one. Dr. Groothuis has many other ways to look at it in the chapter.
The section made me understand why God's age is not "actually infinite". There has to be something beyond the temporal (though God is also within time) which grounds it, since it requires a beginning. This reminds me of Dr. Greene's talk of the calabi yau shaped dimension in "Fabric of the Cosmos". Anyway. All talk of God's attributes being infinite is a matter of quality, not quantity.
Scientific confirmation of a beginning: the Big Bang
Such evidence as Hubble's discovery of the red shift caused by galaxies moving away from Earth, Penzias and Wilson's discovery of the background radiation left-over from the Big Bang, the abundance of helium, and the second law of thermodynamics (moving from minimum to maximum entropy/disorder, or from maximum to minimum energy volume/dispersal)--which can be put this way:
Non-eternal Heat Death argument:
1. If the universe were eternal and its amount of energy finite, it would have reached heat death by now.
2. The universe has not reached heat death (since there is still energy available for use).
3. Therefore, a) the universe is not eternal.
4. Therefore, b) the universe has a beginning.
5. Therefore, c) the universe was created by a first cause (God).
"The only other alternative is that everything came from nothing without a cause" (p. 226).
Some object that to consider the universe as a whole to be entropic commits the fallacy of composition. That fallacy is informal and does not apply to all part-whole relations. The scope of the second law of thermodynamics is universal, and there is no positive evidence that the law is suspended or reversed in any part of the universe.
Some object that the Big Bang model might be wrong--maybe the universe goes through many cycles of expansion and collapse (Dr. Greene says that, even if true, there is still a "first" cycle in "Fabric of the Cosmos")? Maybe there was no singularity and the universe is self-contained, neither created, nor destroyed (Stephen Hawking spoke of "imaginary time"). But, Groothuis quotes Craig and Copan as concluding: "It can be confidently said that, with regard to the standard big bang model, no cosmogonic model has been as repeatedly verified in its predictions, as corroborated by attempts at its falsification, as concordant with empirical discoveries, and as philosophically coherent," (p. 232). Those who object to it, do so on emotional grounds, using words like "repugnant" "preposterous" "leaves me cold" "this difficulty".
Given a choice between God causing the universe, and nothing causing the universe, some choose "nothing" (or its ontological twin: zero energy...which, as stated earlier, isn't nothing...and the energy of which has a beginning).
Some object that the Big Bang takes God out of the equation and affirms Darwinism, whereas Darwinism requires its own evidence, and cosmological arguments give God the credit for the beginning--however the beginning actually happened.
The God of the Cosmological Arguments
Dr. Groothuis shows that a first cause must be a personal, omnipotent, necessary agent which can choose to create. More than one agent is superfluous to posit, according to Ockham's Razor (and how would they all cooperate, given the order evident in creation?). This rules out atheism, polytheism, pantheism (which claims the universe is a necessary being), Hinduism (cyclic universe), and Buddhism (eternal universe). Still, more is needed to argue for the Christian God--the cosmological arguments can only take you to monotheism.