Christian historian Dr. Wallace Marshall and I are debating whether or not enough evidence points to the existence of a god. For background and format, and Dr. Wallace’s opening statement, see entry one. For subsequent entries, see index.
This time we are still focusing on the Kalam Cosmological Argument: in response to my second reply, Marshall presents his latest arguments. I can’t respond to everything for limited space. But in today’s entry I’ll cover the essentials.
That the Evidence Points to Atheism (III)
by Richard Carrier, Ph.D.
We don’t know spacetime had a prior cause, nor could it. And everything else has more plausible causes than gods.
Do We Know Time Has a Cause?
No.
Marshall claims it’s begging the question to say a cause must exist somewhere to exist. No. It’s logically impossible for a thing to exist and never exist and exist nowhere. “Exists nowhere” is a synonym of “doesn’t exist.” Same for time.
Marshall then implies God is not a temporally ordered cause but a “simultaneous” cause. But if spacetime has to already exist for God to exist, he isn’t needed to cause it to exist. Spacetime can exist without anything else existing; but nothing can exist without spacetime. It’s the only known necessary being. We therefore need no other.[1]
We also have no evidence that all things (much less spacetimes) have this kind of cause. We only observe temporal causes. If there is a fundamental “simultaneous” cause of everything, it could just be spacetime. We need no god to explain spacetime any more than we need an additional cause to explain god.
Marshall protests, but he has never shown that “an early state of the universe” cannot be the first cause. If causes can be simultaneous with their effects, then nothing prevents a primordial vacuum state from causing everything else. It would remain as uncaused as Marshall’s god. But just as viable; indeed more so.
Dr. Marshall insists “the cause would have to be spaceless, timeless and immaterial” because it brought all that about, but his allowance of simultaneous causation refutes that. Time might simply just exist, as uncaused as God. Because even God couldn’t exist without it. Nor could he have “pre-existed it” so as to cause it.
Worse, Marshall incorrectly says I’m begging the question when I said laws won’t exist when nothing exists to manifest them. Wrong. That is a logically necessary fact: if nothing exists to produce a causal law, that law won’t exist. Marshall is the one begging the question by assuming without evidence that causal laws will just “exist” for no reason.
Do We Know Time Began?
No.
Marshall claims evidence our local universe began is evidence time began. Wrong. “The [most] standard and [most] widely accepted model of how the universe began” today is the inflationary Big Bang model, which entails countless universes might precede ours. We therefore cannot conclude from our Big Bang that it was the first. All cosmologists concur on this, including every living cosmologist Marshall himself cites as an authority.[2]
Marshall keeps citing Vilenkin as demonstrating time had a beginning, but Vilenkin’s BGV theorem demonstrates this beginning was vastly prior to our Big Bang. In other words, the very theorem Marshall is relying on entails “evidence our local universe began is not evidence time began.” Marshall can’t count on this theorem one moment and repudiate it the next.
And as this is all the current state of the science, thirty year old quotations of dead scientists cannot rebut it.
Meanwhile, Guth has admitted the BGV theorem relies on undemonstrated assumptions, which many cosmologists don’t consider reasonable; such as that all of physics is classical, when we know it’s quantum mechanical. But the BGV ignores quantum gravity, even though we know that’s required to explain the world; therefore any theorem that ignores it cannot explain the world. That’s why there’s no consensus that the BGV theorem is correct.
Krauss explains this to Craig in the video Marshall cites: starting at timestamp 55:50, Krauss says the above: that only quantum models can ultimately be true, yet BGV is not a quantum model. Craig is stymied, resulting in this exchange at timestamp 56:15:
Craig: Isn’t it true that the only viable quantum gravity models on order today involve a beginning?
Krauss: No.
What part of “no” does Marshall not understand?
Marshall says Krauss agreed “all the evidence we have says the universe had a beginning,” but Marshall is confusing “universe” with “existence.” Krauss argued our universe might be one in an eternal chain of universes.
I asked the cosmologist Sean Carroll, “Despite the BGV theorem, are past eternal cosmological models still possible?” He replied [3]:
Yes, of course. The BGV theorem makes assumptions, and those assumptions might be false. Indeed, viable past-eternal models have been constructed. Most importantly, the BGV theorem only refers to classical spacetime, not to quantum gravity. It says nothing at all about whether the universe must have a beginning, only about the limits of the classical approximation.
I also asked whether past eternality could be a result of quantum indeterminism, and Carroll replied we won’t know without a theory of quantum gravity, but, he added:
Certainly the BGV theorem says nothing about the Carroll-Chen model, as (1) it doesn’t conform to the BGV assumptions, and (2) it involves quantum transitions in a crucial way, and the BGV theorem only applies to classical spacetimes.
In my last reply I explained the probabilistic consequence of that Carroll-Chen model: that quantum indeterminism allows past eternality by bypassing the assumptions of the BGV (Boltzmann effects can also do this even in a classical model). That Big Bangs have a nonzero probability of occurring from quantum indeterminism is a fact.[4] Ergo, a past eternal quantum model is actually more supported by current evidence than the BGV, which actually contradicts evidence by ignoring quantum effects.
So we don’t know spacetime had a beginning. Cosmologists’ opinions differ, but when asked, all will admit it’s simply unknown.
Is God a Simple Explanation?
No.
God requires enormous unexplained specified complexity and numerous assumptions nowhere grounded in science.[5] Unlike quantum vacuums, or ungoverned nothing-states such as I explore in The Problem with Nothing. From Propositions 1 and 2 there, all subsequent numbered propositions follow by logical necessity. And those two propositions entail vastly fewer suppositions than a god.
Are Actual Infinities Possible?
Yes.
Dr. Marshall says I have “yet to respond” to his “second philosophical argument” against actual infinities. But I did. I noted actual infinities’ existence in no way depends on their being counted or added up. So his adding argument is a non sequitur, as also explained by all the mathematicians I cited in thorough refutation of all Marshall’s arguments against actual infinities. To none of which Marshall replies.[6]
No living mathematician I know of, who is expert in transfinite mathematics, agrees with Marshall.
I noted Marshall was even misusing Silverman, who did not say actual infinities were impossible. I asked Silverman whether he thought past infinite times were possible. His response? “There might have been infinitely many big bangs and big crunches in a multiverse.”[7] End of story.
-:-
Such is my third response.
Continue on to Dr. Marshall’s reply.
-:-
Endnotes
[1] For those who want to explore this point further, see my development of it in response to Edward Feser in “Feser’s Five Proofs of the Existence of God: Debunked!” (20 February 2018), “Feser Can’t Read (and Other Astonishing Facts)” (3 March 2018), and “Feser Still Can’t Read” (11 March 2018).
[2] I cited numerous examples confirming this in earlier entries in this debate, but start with, again, Leonard Susskind, “Was There a Beginning?” MIT Technology Review (27 April 2012).
[3] Email from Sean Carroll to Richard Carrier, “Re: Debate Question: Quantum Cosmology and Past Eternality” (6 May 2019).
[4] See Sean Carroll and Jennifer Chen, “Spontaneous Inflation and the Origin of the Arrow of Time,” ArchivX 2004, leading to Sean Carroll’s book on the subject, From Eternity to Here (2010).
[5] See Richard Carrier, “The Argument from Specified Complexity against Supernaturalism” (17 April 2018) and “The God Impossible” (8 March 2012).
[6] Everything I cited refutes Marshall; I here repeat verbatim the last two endnotes of my last Reply: Hilbert’s position is refuted in the very introduction to the collection of essays Dr. Marshall cites, as co-written by the renowned mathematician and philosopher Hilary Putnam (see Philosophy of Mathematics, pp. 6-11; Hilbert’s essay therein is an old speech from 1925 included only as a foil). Current mathematical opinion [is summarized in]: Rudy Rucker, Infinity and the Mind: The Science and Philosophy of the Infinite (1982), e.g., p. 296; N. Ya. Vilenkin, In Search of Infinity (1995), e.g., pp. 50-69; quotation and demonstrations: Bertrand Russell, The Principles of Mathematics, 2nd ed. (1938), esp. § 3.23 and all of § 5 (e.g. 5.43). See also the expert commentaries cited in endnote 6 to my first reply in the Carrier-Wanchick debate, and the reference entries: “Is there really such a thing as infinity?” from the University of Toronto Mathematics Network; “Infinity” from the History of Mathematics Archive; and “The Infinite” from the Internet Encyclopedia of Philosophy and “Continuity and Infinitesimals” from the Stanford Encyclopedia of Philosophy.
[7] Email from Herb Silverman to Richard Carrier, “Re: Debate Question: The Possibility of Infinity” (6 May 2019).
The debate question: “Does God exist?”.
Marshall: Assert that everything is caused. Therefore, the primal universe must be caused. Name the causal agent God. Therefore, God exists.
Carrier: Therefore, God must be caused. Name the causal agent God God. Therefore, God God must be caused. Name the causal agent God God God… (etc to infinity)
Marshall: OK, then change it to “Assert that everything, except for One Thing, is caused. Therefore, the primal universe is caused. Name the causal agent God, and assert that God is the One Thing which is not caused. Therefore, God exists.”
Carrier: Agreed, but let’s simplify it to: “Assert that everything, except for One Thing is caused. The primal universe is the One Thing.”
cmessenger99- You have egregiously misstated Premise 1 of the Kalam. Can I encourage you to go back and at least read the basic outline of the argument in my very first entry?
On Kantian models propositions can be supported analytically or synthetically. Looks like Marshall has no interest in the synthetic side (I think he knows he would lose that) so he is focusing exclusively on the analytic. Reminds me of Descartes in his book The Meditations for which see Kant’s book The Critique of Pure Reason.
Danny, perhaps you can elaborate on the relevance of this Kantian distinction to the Kalam argument?
Hi, Dr. Wallace and thank you for your interest in my Kantian comments. You ask about the relevance of those comments to Kalam’s Cosmological Argument. In reply, Kant’s analytic/synthetic distinction provides a useful framework for the analysis of propositions, including whether “God exists.” You have not attempted to show God exists through any synthetic empirical observations, i.e. in a test tube or in some section of the universe as a scientist would do in identifying a new bacteria or a new star. Instead, you plunge into metaphysics by postulating a “disembodied eternal mind” as the cause of the universe which I would regard as “analytic” as opposed to “synthetic.” I do not see how any metaphysical statement can be regarded as “synthetic.” Dr. Carrier has ably shown the shortcomings of your approach in his responses to your arguments and I will not repeat those here. Hope that helps some-if not feel free to disregard my comments.
“Exists nowhere” is a synonym of “doesn’t exist.”
well not really – eg Muslims say God ixists without a ‘where’ or direction as the ‘where’ (and ‘when’) is inventid by God, whu is beyond time and space.
The problum is that by analogising u subject him to time and place which nesasrily yields a misplaced ansr.
“Exists nowhere” is still a synonym of “doesn’t exist.” That there are theists who refuse to admit that fact does not change that fact. It’s just another commitment to an incoherent belief, like Nicene Trinitrarianism.
It’s obviusly not a fact – ur mere upiniun which u call a ‘fact’. God ixists nowhere in this univurs – sure.
cuz ‘whereness’ is an attribut’v this univurs.
And why shud god be coherunt tu u? why shud he be subjict tu accidunts’v time and place when these things ar inventid by him and relate tu this univurs.
ur fundamental errur is mixing up creatur and creator. which is a basic rudimentry howlr.
‘There is nuthing like God’ quran 42.
Ale bin Abe Talib states
أن الإمامَ علىَّ بنَ أبِى طالب رضى الله عنه قال: “كان الله ولا مكان، وهو الآن على ما عليه كان”.
which means: << Allah ixistid and there was no place, and He now is as He was. [i.e., without a place]>>
God ixists but isn’t subjict t ‘wher’ or ‘how’ or ‘when’ or ‘why’. that is islamic sunne theism 101.
Imam Ahmad ar-Rifa^iyy al-Kaber, who lived around the year 600 after Hijrah, said:
قال الإمامُ أحمدُ الرفاعىُّ الكبير: “غايةُ المعرفةِ بالله الإيقانُ بوجوده تعالى بِلا كيفٍ ولا مكانٍ”
which means: <<The ultimat knowledge about Allah is to be certain that Allah exists without a how or a place. Imam Muhammad Ibn Hibah al-Makkeyy, wrote a book called Hada’iqul-Fusul wa Jawahirul-^Uqul. It came to be known as Al-^Aqidatus-Salaheyyah, after he gave it as a gift to Sultan Salahud- Din al-Ayyubeyy, who ordered that this book be taught to the children in schools and broadcast from the top of minarets. In his book he said:
قال الإمامُ محمدُ بنُ هِبَةَ المكّىُّ فى قصيدته “حدائقُ الفُصُولِ وجواهرُ العُقُول” المعروفةِ أيضًا باسم “العقيدة الصَّلاحية”: “قد كان موجودا ولا مكانا وحكمُه الآن على ما كانَا”
Which means: << Allah existed eternally and there was no place, and the judgment about His existence now is that He is as He was [i.e., without a place]>>.
Imam Ja^far as-Sadiq said: <<He who claims that Allah is in something or on something or from something commits shirk (blasphemy). Because, if He was in something, He would be contained, and if He was on something, He would be carried, and if He was from something, He would be a creature.
Shaykh ^Abdul-Ghaneyy an-Nabuluseyy said: <>
Imam Fakhrud-Den Ibn ^Asakir said in his ^Aqedah: Allah existed before the creation. He does not have a before or an after, an above or a below, a right or a left, an ahead or a behind, a whole or a part. It must not be said: When was He, Where was He, or how was He? Allah exists without a place. He created the universe and willed for the existence of time. He is not bound by time or designated with place.>>
Imam Abu Sulayman al-Khattabeyy said: <<What is obigatory upon us and upon every Muslim to know is that our Lord has no shape or form, because the shape has a <>, and <> does not apply to Allah or His Attributes.>>
Know beyond doubt that the question <> (kayf:كيف:) does not apply to Allah. <<How?>> is a question related to shapes, bodies, places, depths, and dimensions. Allah is clear of all such attributes. Also be firm that it is invalid to say about Allah <<… but we do not know how>>, because in essence, it falsely indicates that Allah has a color, shape, dimensions, body and place, but one is simply ignorant of its <>.
Imam al-Ghazaley said: << Allah, the Exalted, existed eternally and there was no place. He is not a body, jawhar (minute indivisible particle), or bodily property, and He is not on a place or in a place.>>
What is a fact is that this is all illogical incoherent nonsense. So citing them believing illogical incoherent nonsense does not make it “not” illogical incoherent nonsense.
It is logically impossible to both exist and exist nowhere. That Muslims believed in a logically impossible God is just to be expected; almost all actual gods believed in today are logically impossible objects of irrational faith. The Christians did the same thing by inventing a completely incoherent Trinitarian god at Nicea. Religious believers have a long established tendency to believe illogical things.
Nor dus saying it’s ‘illogical inchorent nonsense’ makit so.
It’s really quite basic Dr Carrier.
‘whereness’ is a propurty’v this univurs. surtnly god is no wher in the univurs. we’r agreed.
God ixists ‘without’ this univurs. therefor and iniluctably he’s not subjict t this univurse ie not subjict tu whers, wherfors, hows, whens, causes, accidunts nor the 6 directions or any dimensns.
ur fundamental errur is t think: since he can’t be in the univurs…he can’t ixist or if he dus ixist, sho me where in the univurs is he locatid. both miss the mark.
the univurs is his creasn – how on urth – is he within his univurs he creatid
(for that u must turn t incarnasnal theolojies’ or non sunni maturede/ash’are wuns like the corporealists, the ‘stuffers’ hashweyyah, the anthropomorphists and salafes/wahaabes/ibn taymeyyah whu believ god has a body and dimensiuns etc – a bit like ur logic: how can god ixist without a wher or a size.
Indeed. “God exists in none of the places anything exists” is simply saying he doesn’t exist. No matter how much one might wish it would make sense for God to exist “outside” of everything, that’s simply illogical, and thus impossible.
Thanks for all the links, Dr. Carrier. Fascinating reading. It seems the science regarding the beginning of our universe is far more complicated than “the universe began to exist.” I’m enjoying all the comments as well.
How life was or is constantly created is the unanswered question that might lead to a god existence. Laws or theories might well describe and trace down our own universe(es), but no quantum or relativity theories or any other I have read off attempt to explain the phenomena describing the transition from unanimated to living organisms (from pure matter and energy to living things). So, whether if the universe is finite/infinite in principle, and that a casual origin to explain it may be related to god existence, the focus should be centered on how the “living” made its way out of the “dead”, which is at the end what enable us to entangle ourselves in these sort of discussions, as it is clear that without life itself, nothing else “exist”. And I’m not thinking of elements and conditions suitable for life, but to the actual transition from organic materials, to self-motivated living organisms (at their more fundamental level).
Also comes to my mind solipsism or simulation theories, in which giving the case, there wouldn’t be any ground floor to start any kind of discussion.
A last thought: If infinite can’t exist, then how god might exist at all? This implication would mean no possible god proving by any sort of scientific/logical/probabilistic means, and all possible explanation may be well left to good will or faith. In which giving the case too, this debate and its arguments proving god existence is nonsense.
I don’t know what you mean by “constantly” created. Where do you see it being “constantly created”? Do you mean, how life reproduces? That is not an unanswered question. We’ve fully answered it in chemistry. And indeed, that it’s all just blind chemistry is evidence against it being supernaturally caused.
If you mean instead biogenesis, we have not observed a second instance; we can only calculate that such instances are highly likely universe-wide. We do not know sure sure which of many processes we know can do it did it in our case, because the evidence has been destroyed. But we have enough evidence to know there are many random processes that would inevitably have done it somewhere in the universe; and we will then be one of those somewheres.
Indeed, the total body of evidence regarding this so far is evidence against it being supernaturally caused.”>is evidence against any god being involved.
Then you have not read any relevant science. You need to catch up on the vast body of protobiological science published to now. We have numerous physical models for the transition from standard chemistry to biochemistry. All are plausible and rely only on confirmed or observed phenomena.
You seem to be confusing various different things here.
Motivations are a property of neural systems, which are very late comers in the evolution of life. How neural systems manifest motivations in general is actually reasonably well understood. As is how they evolved from other organic systems.
But for most of the earth’s history (billions of years) no life had neural systems, or indeed organs at all. The first life was protocellular. Which evolved into single called organisms (e.g. bacteria). Which are just biochemical computers, and their operation and reproduction and behavior we have fully explained down to the atomic level. Then after a billion or so years these evolved into undifferentiated multicellular organisms (e.g. algae). Then after hundreds of millions more years these evolved into differentiated multicellular organisms, i.e. organisms with different tissues and organs constructed out of single cells copied over and over. These included plants, which have no neural systems; and animals, which do. And we know quite a lot now about how all this happened, including why it took so long, and started so basic.
I’m not sure what you mean, but yes, some philosophers have pointed out the problem that if actual infinities cannot exist, God cannot have infinite knowledge. But that would only entail a modification to the abilities of God. It’s not really an argument against God.
Dear Dr. Carrier,
First of all, I would like to say that I really appreciate you have taken the time to read my comments and provide clarification to them. I think I was not clear nor specific when writing my reply. So even it might be that you have already answer some of my points, I don’t want to lose the chance to extend my thoughts if you don’t mind. It took some time for me to answer as this time I wanted to do some research to better understand your reply, and to try to be clearer on mine.
First, I want you to know that I’m on your side, and don’t believe that our universe must have a purpose, and that there is a god behind it. But I’m trying to make a point (which might not be useful at all) to try to change the start point of the discussion from how the universe has been created, to the fundamentals of the creation of life. I personally think that if a god really exists, his purpose of o universe without life won’t make sense at all, therefore life itself must be the center of the discussion.
When I mean how life is constantly created, I don’t mean life here on earth, or even in other places in the universe where life already exists and continues to evolve. What I wanted to mean is to the precise moment in between when an organic material crosses the barrier from being inert to be alive, or how life have begun at all, considering the definitions that distinguishes something from being dead to that that is alive (like for example, the fact that living organisms manage the conversion of ingested fuel into usable energy which only living organisms can do).
You are right as I have not read enough. But I tried to change this. Now I know that even when I didn’t know, I have already read some protobiological literature, just was not aware of the concept at all, and I’m glad to know now that I was already in agreement with the concept.
Also, I have also read now several articles related to physical models for the transition from standard chemistry to biochemistry. I might not have the right knowledge to fully understand all the concepts that are related into this. But at a basic level what I have understood is that they try to understand the biochemistry that takes place within every living organism, and the approach taken where quantum mechanics tries to explain these processes, as it seems that that these reactions can’t be fully explain in a common laboratory. But what I want to mean about a starting point of life, is not to understand how living organisms operate, but at a more fundamental level, why do they started to behave as a living organism at all. Do these models try to explain this too? Is there any literature you could recommend me where I can read about?
Thank you,
Ricardo.
This universe is not only almost entirely hostile to life, it is just about as hostile to life as it could be and still contain life to be observed. Which is exactly what is predicted by random formation and counter-predicted by any “designed for life” hypothesis. Follow the links I’ve provided you.
And as to what you mean by matter that is nonliving becoming living, it’s still not clear which exact phenomena you are talking about, but you clearly don’t have any knowledge of biochemistry, which has already explained all this. There is no mystery as to how one set of chemistry becomes another: how chemical systems without metabolism, movement, and reproduction become chemical systems with metabolism, movement, and reproduction. There is no mystery at all to it now. It’s straightforward chemical mechanics. Which is actually evidence against anything supernatural being involved, much less gods.
And yes, biochemistry explains everything about this. Reproduction as a chemical computer. Metabolism and movement as a computed function governed by interactions between the stored information and the chemical agents that effect results. Even thought, neural systems, are entirely reducible to basic chemical interactions. There remain some unsolved questions (e.g. how to reach the level of consciousness; how to account for the qualia of consciousness), but those don’t exist in the biosphere until extremely late in the evolutionary timeline (and thus are not distinctive of life as such; but are only a highly complex form of life).
I don’t know what you mean about quantum mechanics. Life does not exist at a quantum level. It is formed by classical physical processes, which emerges from quantum mechanics, and are in some trivial ways affected by it. But quantum effects themselves are actually not required, or even all that importantly involved. They are just an unnecessary oddity. Yet more evidence against the involvement of any creator.
well u’r duing a great survis t sunne muslims Dr Carrier –
The ash’are/maturede sunnes have been arguing spilling planit loads’v ink against the corporealists,
that t’ affirm a geographical ‘where’ for god is t’ cummit ‘shirk’ – polytheism – since God cannot ixist any ‘where’
ie that he ixists no ‘where’ – that he nesasrily ixists sans where, sans how, sans wherefor, sans when.
even the beatific visiun dusn’t intail ‘direction’ or
distance or fotons etc.
If he ixistid any ‘where’, he’d be part’v the univurs.
the wahhabes reasun as u du: if he dusn’t ixist any where’…he dusn’t ixist full stop.
but ‘whers’ and ‘whens’ etc are cuntinjunt upon this univurs but god is transendunt.
Sadr ush-Share
ah Allāmah Mufte AmjadAle `Azame states: “Allāh is free from direction, space, time, movement, station, shape, size and all that which is creatid [hādith].None of your last comment is intelligible.
Now I just made a mistake. I meant to say that I think he meant to say pan-en-theism.
May I try again [please delete the previus unintelligibl comment]
Your response sounds very much like the anthropomorphisers/corporealists salafe/ibn/taymeyya/wahhabe objection to sunne ashare/maturede belief: that the sunne god is but a figment.
The sunnes say that assigning a place to god ie that God is litrally above the throne in hevn – intails polytheism [shirk] since god cannot ixist any ‘where’ in any place (or in any ‘time’ or any ‘how’.)
T’ say god ixists must mean god ixists in some place nesasrily means he’s part’v the universe which is to make him part of creation – which is impossibl.
God ixist without a place ie without a universe.
You seem less opposed to god ixisting without a ‘when’ ie timeless.
Do you also hold that to ixist at no time is to ixist not at all? As you hold with place?
[the sunnes also say that the beatific vision will hapn without direction or distance]
A sunne skolar Sadr ush-Shareah Allāmah Mufte AmjadAle `Azame states:
“Allāh is free from direction, space, time, movement, station, shape, size and all that which is creatid [hādith].
All you are doing is repeating the same thing: that some theologians have “said” God must exist or have existed nowhere and never. And I am telling you that’s illogical. Continuing to repeat their illogical statements doesn’t make them logical.
I’m not Muslim but I understood “all” of what he said. I disagree with most of Islam but that doesn’t mean they can’t observe or reason out some truths by observing and pondering this universe. There are (I think I’m assuming we’ll, I don’t know all religions) most likely truths in all religions, including atheism. I think he meant, however, to say pantheism rather than polytheism. I think you are rushing through these comments. You certainly distorted or misunderstood my comments so far.
So this muslim argument reads “Since we could not find any of the qualities of existence in God, we then defined it as having none of the qualities.” I.e. you defined God as nonexistent and then said that because it fits the definition, it exists. It requires more than that to prove the existence of something.
The BGV theorem is sometimes used as proof that the universe “must have an absolute beginning”. However, (1) the BGV applies only to inflationary models. It shows, if it’s correct, inflation is past-incomplete, and require physics other than inflation to describe the boundary condition. This paper is a direct response to physicists who attempt to use inflationary models to describe an eternal universe. However, there is a difference between “past-eternal inflation” and “non-singular cosmology” or “cyclic cosmology.”
Even Borde, Guth and Vilenkin clearly suggest that a “beginning” is merely one possibility that might correspond to the boundary condition. They wrote: “Inflation alone is not sufficient to provide a complete description of the Universe, and some new physics is necessary in order to determine the correct conditions at the boundary. This is the chief result of our paper.” In an exchange of emails between Vilenkin and the physicist Victor Stenger, Vilenkin said that “you can evade the theorem by postulating that the universe was contracting prior to some time.”
So, it’s clear it doesn’t prove the universe had an “absolute beginning.”
(2) In addition, Alexander Vilenkin explained that the theorem predicts that if the universe is everywhere expanding (on average), then the histories of most particles cannot be extended to the infinite past. In other words, if we follow the trajectory of some particle to the past, we inevitably come to a point where the assumption of the theorem breaks down—that is, where the universe is no longer expanding. However, Anthony Aguirre clarified that this is true for all particles, except a set of measure zero. In other words, there are rare particles whose histories can be infinitely long. These particles have worldlines [trajectories in space-time] that extend indefinitely into the past, and can prevent there being a time at which the universe is not expanding. The fact that they are rare does not make them unimportant, because they nonetheless thread a physical volume.
In other words, not all geodesics are incomplete: in particular, it does not apply to the comoving geodesics themselves. Thus there is nothing preventing some geodesics from continuing arbitrarily far into the past. Anthony Aguirre – Eternal Inflation, past and future (pg.20) and The Fallacy of Fine-Tuning (chapter 6.1.)
(3) Another problem with this theorem, according to Sean Carroll (article: Let the Universe Be the Universe) and Ivan Aguillo (Before the Big Bang: Loop Quantum Cosmology – SkyDivephil), is that it only takes classical spacetimes into account — “classical” in the sense that it is a definite four-dimensional Lorentzian manifold, not necessarily one that obeys Einstein’s equation of general relativity (It’s like saying “start with a path of a particle, but not necessarily one that obeys Newton’s Laws.”). Carroll explains that the theorem says that such a spacetime, if it has been expanding sufficiently fast, must have a singularity in the past. But the problem is that it’s naive to think that any result dealing with classical spacetimes can teach us anything definitive about the beginning of the universe. The moment of the Big Bang is a place where quantum gravity is supremely important. The Borde-Guth-Vilenkin results are simply not about quantum gravity.
It’s extremely easy to imagine eternal cosmologies based on quantum mechanics that do not correspond to simple classical spacetimes throughout their history. The BGV is an interesting result to keep in mind, but nowhere near the end of our investigations into possible histories of the universe.
(4) Furthermore, Leonard Susskind, who is professor of theoretical physics at Stanford University, has argued that past-eternal inflation (that is, an eternal multiverse) is feasible (article: Is Eternal Inflation Past-Eternal? And What if It Is?). He presented equations to support this conclusion and addressed the arguments against his position. Yasunori Nomura (article: The Static Quantum Multiverse) also adopted this position. In the article titled Singularity Resolution in Loop Quantum Cosmology (pg.9), Abhay Ashtekar reinforced the idea that the BGV does not apply when quantum gravity is taken into account.