Because a small error in the beginning is a great one in the end ~ Aristotle
Let's take an example of something we know at least a little bit about the universe, the properties of quantum mechanics and relativity.
Can you form a LOGICAL argument, completely absent ANY premise grounded in empirical findings, that supports the conclusion that the universe will have either of these rather surprising properties?
I sincerely doubt that you can for the reason I stated, conclusions must be based on facts, not on logical propositions which merely alledge facts.
When we propose that we can, through pure reason and logic, conjure what are rightly factual premises that demand supporting evidence out of our conclusions we make a grievous error from the very beginning.
And neither can a LOGICAL argument, in the absence of facts, discern the origin of the cosmos. For any conclusion of LOGIC to be valid the premises have to be grounded in fact. Mathematics and logic themselves are grounded in an observation of the universe, not the other way around. 1 + 1 equals 2 based on observation, not arbitrary fancy. We then made further observations and (over a very long period of time) discerned a set of rules (axioms) that appear to be self-evident (which demands that they correlate with observation) from which all other conclusions follow. The same goes for the axioms of logic. If we adopt axioms which are directly contradictory to observed fact then we will reach absurd conclusions. Now sometimes we might 'try' out an axiom on a what-if basis and conclude that the results are entirely consistent with reality (what-if the square root of a negative number is a valid concept? well that allows us to use mathematical notations that are isomorphic with observed reality so we conclude that it is a valid axiom).
There is a saying in computer programming that applies here: Garbage In - Garbage Out. If you feed Garbage In like "that which begins to exist", then you get Garbage Out. You have absolutely no observational knowledge about what "begins to exist" *really* means, you just assert it because it sounds nice. But you simply cannot extrapolate from our observations from WITHIN the construct of the Cosmos that mere rearrangements of things (mass-energy and spacetime) - which is what we are talking about when we say a pencil "begins to exist" - must necessarily follow the same rules as the origin or eternal existence of the mass-energy or spacetime itself. That is the equivocation at the heart of these arguments. These are entirely different categories of phenomena. You cannot assert based on any actual knowledge that mass-energy or spacetime (aka a universe) begins to exist in the same way that we observe mere rearrangements of pre-existing mass-energy and spacetime (aka a pencil). The more logical conclusion is that there is something deeper to the Cosmos in which these universes exist or come into existence that we have absolutely no knowledge about at this time.
You cannot even begin to talk about it because have no concepts to even begin to speak about such things.
Explain magnetism to me. Deeper. Why? Why? Why? How far down can you go? You think you understand it? I can assure you with some certainty that you do not understand it, you only pretend to understand it at some high level. Our very best physics only gives a mathematical description of the forces and force mediators. There is no physical description you can give that will account for magnetism and be accurate. It simply isn't known. We know even less about spacetime, it is extremely difficult to measure such things and our sciences are only just starting to scratch the surface. There are possibilities that describe MULTIPLE DIMENSIONS OF TIME. What does that even mean? How can you pretend to talk about the origin of the universe when you don't know what time is, you don't know if it's an independent thing or part and parcel, or even for certain if there is only one of them. Furthermore, Einstein destroyed even our notions of simultaneity within time - we can't even necessarily say two things happened "at the same time". In my reference frame A happened before B and in yours B before A.
And yet, you want to pretend to know enough to say that you know everything "came into existence" at the Big Bang? That isn't even what the Big Bang *actually* states. Prior to that there was possibly a singularity or something - we don't really know. We don't possess even the mathematical description that will account for this supposed singularity state. It's a handle we use to talk about this unknown state. We only posit it exists because we measure the universe as expanding today, and rolling time backwards the logical conclusions is that it was smaller and smaller as we go backwards in time. Now we do have a very accurate description of the physics of OUR universe - it's not perfect, we know that, but it IS accurate enough (based on measurements from things like the LHC, and the energies involved) to roll back the clock a very long ways. And then our present model of physics ceases to be applicable - but that only happens when the "everything" that we know, was in a tiny microscopic little bubble of spacetime and at least near infinite energy and density. Before that? We Don't Know. And on our ignorance it's entirely UNreasonable to conclude that it magically all popped into existence due to the will of some being who wants to watch us Masturbate and send us to eternal punishment if we get about it too often. That is an absolutely, fatous, insane leap of illogic.
We Don't know that spacetime or mass-engery was created, as I've already argued. There are some hints that it wasn't per se. One such hint is that if you take the totality of energy that we can measure in the universe today, it sums to JUST ABOUT Zero (and the error bars of that measurement allows for a Zero value). Now just imagine, what if the total energy of the universe turns out to actually BE Zero? If that's true then there is one phenomena that we observe today that might be relevant to the discussion and that is the Quantum foam of virtual particles that we MEASURE as necessarily existing for the measurements of QM to work out properly. These virtual particles necessarily sum to Zero total energy and they burst briefly into "existence", leaving only their fingerprints on the Quantum field and then ultimately annihilating and ceasing to exist (for lack of our deeper understand and the words to express it).
You might read this and shrug it off but it is a rather astonishing result, possibly the most astonishing in all of human history.
There is no theoretical limit to the size of these fluctuations but QM theory does presume that the greater the energy of the event the shorter the duration. That generally holds true (this result is built-into the equation of QM field theory) but there is a possible loop hole. If there are certain types of symmetry violations that are possible (and we're just today beginning to reach the energy levels required to measure them) then a fluctuation of unimaginably large proportions could leave behind a tiny remnant, a "new universe" that explodes "into existence", ripping spacetime itself out of the quantum plenum (as it were) and then expanding, at least in the case of our universe, as per modern inflationary Big Bang cosmology has been able to discern.
The scientific theories will stand or fall based on the strength of the evidence we discover going forward, either supporting them or rendering them untenable.
Ultimately, the only thing I see these types of Cosmological arguments demonstrating is that we are limited by what we can measure of the universe from the inside. There is almost certainly a greater construct within which the entirety rests but I think it is unreasonable to assume that greater construct is outside of the universe rather than merely being that part of the universe that is inaccessible from the inside. Imagine a cellular automata executing on some hardware system, carrying out the instructions that form the laws for that 'universe'. Those laws might result in patterns that store and process information about their surroundings and those patterns might eventually discern the patterns that define the apparent 'laws of the universe' that act upon the cellular automata. But NOTHING is revealed that represents the instructions running the cellular automata itself, nor anything about the computer system upon which it is running. But the cellular automata is not external to nor independent from the totality of the system. It's just that from within the construct you CANNOT access the information that would be necessary to truly understand the whole - that is, you cannot jump up a level. No amount of logical reasoning from inside the cellular automata could deduce the proper conclusion.
The 'beings' existing inside this cellular automata could ponder the origin of their universe by presenting these SAME fallacious arguments, but they would be entirely wrong in their conclusions. They would be making arguments from ignorance about the very nature of their own universe.
So I PROFOUNDLY doubt that we can say anything at all meaningful about the kinds of beginnings necessary to say anything meaningful about the origins of either our Universe or the greater Cosmos as a whole [which does NOT mean we cannot say ANYTHING meaningful about the universe either, it means that we must use the strongest observable facts when we draw conclusions - and where we lack knowledge we can only postulate a vast array of possibilities which we then must test against reality, not just pretend that one of the more absurd of them is true]
The Cosmic Triangle: Assessing the State of the Universe
(Hitchhiker's Guide To The Galaxy on the Babel fish) Now it is such a bizarrely improbable coincidence that anything so mindbogglingly useful could have evolved purely by chance that some thinkers have chosen to see it as the final and clinching proof of the non-existence of God. The argument goes something like this:
"I refuse to prove that I exist," says God, "for proof denies faith, and without faith I am nothing."
"But," says Man, "The Babel fish is a dead giveaway, isn't it? It could not have evolved by chance. It proves you exist, and so therefore, by your own arguments, you don't. QED."
"Oh dear," says God, "I hadn't thought of that," and promptly vanished in a puff of logic.
"Oh, that was easy," says Man, and for an encore goes on to prove that black is white and gets himself killed on the next zebra crossing.