At the end of The Eternally Inflated (Multiverse and WLC), I mentioned reliance "on argumentation from (false) ignorance". It's a fair question if you were to ask: what the hell is false ignorance. Let me to clarify.
An appeal to ignorance is a fallacy in which, for example, an apologist might say something like "There is no other know reason why X would happen, therefore god did it" or "You can't prove that god doesn't exist, therefore it does".
What I mean by false ignorance is the sort of move performed by an apologist, where he or she claims ignorance regarding evidence against his or her case, despite that evidence being readily available. In some cases, the feigned ignorance is all the more egregious because not only is the evidence readily available, but it is a matter of public record (in video and transcript) that the evidence has been presented.
Here are some pertinent examples - all centred on arguments raised by WLC - that are raised by people interviewed by Skydive Phil and co in recent films (look for the tag "Before the Big Bang"):
Misrepresenting The BGV theorem
WLC constantly informs us that the BGV theorem means that the universe had a beginning: (debate with Sean Carroll, March 2014) "In 2003 Arvind Borde, Alan Guth, and Alexander Vilenkin were able to show that any universe which is, on average, in a state of cosmic expansion throughout its history cannot be infinite in the past but must have a beginning."
One of the authors, Alan Guth says that's not correct, the theorem only implies that inflation had a beginning. While, it is true that Vilenkin has subsequently written an article which concludes that the universe "probably" did have a "beginning", he caveats the term "beginning" so as to be "synonymous to past incompleteness" - so this does not necessarily mean an ex nihilo creation event.
The conclusion to the actual BGV paper is revealing: "Our argument shows that null and time-like geodesics are, in general, past-incomplete in inflationary models, whether or not energy conditions hold, provided only that the averaged expansion condition Hav > 0 holds along these past-directed geodesics. This is a stronger conclusion than the one arrived at in previous work in that we have shown under reasonable assumptions that almost all causal geodesics, when extended to the past of an arbitrary point, reach the boundary of the inflating region of space-time in a finite proper time (finite affine length, in the null case)."
Note the caveats: "in general", "provided that", "under reasonable assumptions", "almost all", "in the null case". Even if we look past those caveats, we see that the authors are making a claim about a "boundary of the inflating region of space-time". This says nothing about what did or did not exist prior to that inflation.
Finally, Sean Carroll told WLC this in his rebuttal speech during their debate: "Now there’s a theorem by Alan Guth, Arvind Borde, and Alex Vilenkin that says the universe had a beginning. I’ve explained to you why that’s not true but in case you do not trust me I happen to have Alan Guth right here. One of the authors of the Borde-Guth-Vilenkin Theorem, Alan what do you say? He says, “I don’t know whether the universe had a beginning. I suspect the universe didn’t have a beginning. It’s very likely eternal but nobody knows.” Now how in the world can the author of the Borde-Guth-Vilenkin theorem say the universe is probably eternal? For the reasons I’ve already told you. The theorem is only about classical descriptions of the universe not about the universe itself."
In his February 2016 debate with Kevin Scharp, WLC trotted out his version of the BGV again, claiming it as evidence that universe (or multiverse has an absolute beginning).
Pushing the Past Eternal
WLC claims, for a number of reasons, that the universe cannot be eternal in the past. One of the authorities that he calls on in support of this claim is Alan Guth. Guth explains in Before the Big Bang 4 : Eternal Inflation & The Multiverse why he favours models that are past eternal.
Despite WLC's protestations, there are a number of models which are consistent with past eternality: the cyclic model (possibly with one bounce only), conformal cyclic cosmology, loop quantum gravity and dual arrow of time models such as that being worked on by Alan Guth and Sean Carroll.
Therefore, WLC's claims are based on false ignorance. He has no justification for believing that there are no workable cosmologies that are past eternal.
I'm not big into Boltzmann brains, for reasons that I plan to write about in the near future. WLC loves them. The reason why he loves them, as best as I can see, is that it makes physicists look silly when they take the idea seriously.
However, when WLC raises Boltzmann brains, he does so to discredit the idea of a multiverse (which he sometimes refers to as a "World Ensemble"). The problem that WLC has when does this, as Alan Guth points out, is that Boltzmann brains are a problem even for single universes and the multiverse (particularly the pocket universe solution that creates new pockets of low entropy space-time in which low entropy observers like ourselves could develop) is the solution to that problem.
But even if that weren't the case, the argument as presented by WLC himself is only that high entropy, short-lived Boltzmann brains are more likely than low entropy, slowly developed observers. There is no claim that we are impossible under the assumptions being presented. So with a "World Ensemble" theory, it is possible for intelligent life like ours to develop and, therefore, given enough "worlds" in that "ensemble" (as N approaches infinity), the existence of our type of intelligent life within the ensemble becomes a virtual certainty - no matter how unlikely it might be.
Going Low with Entropy
This is in a similar vein to the Boltzmann brain argument, although a whole lot less silly. WLC claims that the second law of thermodynamics, that entropy tends to increase, implies the universe cannot be past eternal. Again, this is put to bed by the multiverse, particularly of the sort suggested by Alan Guth and also the Conformal Cyclic Cosmology championed by Penrose, another physicist who has been widely misrepresented on this subject by apologists, including WLC. Both Guth and Penrose suggest that the solution to the mystery of why the entropy state of the universe was so low prior to the big bang was that there was a "before" the big bang that put the entropy into a relatively low state.
Note that I use the term "relatively", by this I mean to highlight that there is no upper limit to entropy.
Misrepresenting Anthony Aguirre
In his debate with Sean Carroll, WLC selectively used words from Anthony Aguirre and John Kehayias to claim that the universe must have had a beginning:
It is very difficult to devise a system – especially a quantum one – that does nothing ‘forever,’ then evolves. A truly stationary or periodic quantum state, which would last forever, would never evolve, whereas one with any instability will not endure for an indefinite time.
These are taken from the paper "Quantum Instability of the Emergent Universe". The footnote, provided to the transcript but not presented at the actually debate, clarifies that Aguirre's argument is specific to the Ellis-Maarten model but then claims that "their point is generalizable".
Aguirre himself (in the film) confirms he only claimed that a particular model (the "Emergent Universe” of the paper's title) doesn’t work in creating an eternal past, and he goes on to clarify that other models do work with an eternal past, thus putting a lie to WLC's claim that the point was "generalizable".
Conformal Cyclic Cosmology
In one of his podcasts and in a Q&A response, WLC claims that Penrose's conformal cyclic cosmology (CCC) is not a cyclic model (noting that he shares credit for this argument with James Sinclair and makes a philosophical appeal to Yujin Nagasawa's authority). The general thrust of the argument centres on the claim that Penrose's model does not describe consecutive cycles of the universe, but rather that the cycles are concurrent, sharing a common beginning. In Skydive Phil's film of an interview with Roger Penrose, Penrose directly refutes this notion stressing that the conformal cycles of his cosmology do not originate in a common beginning and instead are sequential.
This film was released after WLC made his comments about the CCC model, but it is interesting that Craig has made no effort to modify his position (and this is despite the fact that one of WLC's own domains, the Reasonable Faith Forums, contains links to the film).
Ignoring the Evidence (for Multiverses)
WLC has claimed that there is no evidence for a multiverse, although does temper this appeal to ignorance with claims that if we were living in a multiverse, then we should be swamped by Boltzmann brains (see above). This approach really needs to be modified now, either by relying more strongly on the rather silly Boltzmann brain argument, or by moving to a position similar to Jeff Zweerink's (fundamentally, he claimed - at least in the linked clip - that no matter whether a multiverse exists or not, the case for christianity will be made stronger). To be able to make this latter claim, however, will demand a new stratum of false ignorance as WLC and his fellow apologists wilfully ignore the consequences of multiversality.
If WLC were instead to continue to claim that there is no evidence for a multiverse, he would be wilfully ignoring the words of George Efstathiou, one of the world's top observational cosmologists, who gave a press conference for ESA's Planck satellite (and spoke during the film) saying that there is evidence for a multiverse. Very specifically, there is evidence of inflation and inflation of the sort that very strongly favours a multiverse.
So, in conclusion, what I mean by an appeal to (false) ignorance is the sort of ploy in which an apologist either pretends to not know about inconvenient facts, or protects his argument against contamination by inconvenient facts, and effectively makes a doubly fallacious appeal to ignorance. WLC seems to have been guilty of this in at least seven cases.
I say "seems" because it's possible that I have been overly harsh and WLC is in the process of fixing his errors. We will know that to be the case if, in the future, his debates no longer make these appeals to false ignorance.
Either way, a couple of his key arguments are in tatters.