Sean Carroll debates William Lane Craig on cosmology and God’s existence

Carroll was as good of a speaker as Craig in terms of style. Very easy to listen to, very quick on his feet, very civil. There was no clear winner on style.

It was difficult to assess the truth value of scientific points being made, especially for the layperson. I explained a few of them in my posts earlier this week, but I think laypeople might struggle with them if they are hearing about these things for the first time.

A couple of Craig’s slides: (click for larger images)

Slide 1 of 2:

Dr. Craig slide #1 of 2
Dr. Craig slide #1 of 2

Slide 2 of 2:

Dr. Craig slide #2 of 2
Dr. Craig slide #2 of 2

Quick summary: (this is not complete, because I couldn’t get everything they were saying noted)

Dr. Craig defended two arguments: 1) the kalam cosmological argument and the fine-tuning argument.

Dr. Craig supported the origin of the universe with 1) the expansion of the universe and 2) the second law of thermodynamics.

Dr. Craig said that the BGV theorem supports a beginning for the universe.

Dr. Craig said that the consensus of scientists did not accept Carroll’s naturalistic cosmology, quoting Stephen Hawking in support.

Dr. Craig said that multiverse models fall victim to the Boltzmann brain problem, where we should observe Boltzmann brains coming into existence and then phasing out again far more probably than embodied minds. But we observe embodied minds, and no Boltzmann brains.

Dr. Carroll said that science cannot study metaphysical questions.

Dr. Carroll said that science is about making models that may or may not be consistent with the experimental data.

Dr. Carroll said that the BGV theorem does not support a beginning for the universe.

Dr. Carroll proposed 17 alternative cosmologies, but did not provide a shred of scientific evidence for any of them, the way that Craig did for the standard model.

Dr. Carroll refuted Dr. Craig’s citation of Stephen Hawking, and Craig yielded the point.

Dr. Carroll speculated that science might progress to the point where the fine-tuning can be explained without an intelligent cause, and he gave an example of where that happened (inflation).

Dr. Craig argued that all 17 of the models suggested by Carroll either conflicted with evidence, had serious problems or did require a beginning.

Dr. Craig argued that Carroll’s own model required a beginning.

Dr. Craig argued that Carroll’s own model fell victim to the Boltzmann brain problem.

Dr. Craig argued that Carroll’s own model violated the second law of thermodynamics.

Dr. Craig re-stated his point that the baby universe spawning in Carroll’s model was speculative and incomplete, and cited Christopher Weaver’s work.

Dr. Carroll denied that things that pop into being out of nothing require a transcendent cause.

Dr. Carroll reiterated that science can only make naturalistic models, and that he did not have to answer questions about ultimate causes.

Dr. Carroll showed a photo of Alan Guth expressing his opinion that the universe is “probably” eternal. No evidence was given for this assertion.

Dr. Carroll said that the fine-tuning was not done in an optimal way, because one fine-tuned value was lower than it needed to be, and it should be exactly what it needed to be if God did it.

Dr. Carroll said that a finely-tuned universe is more probably in naturalism than in theism, because God can do anything he wants and doesn’t need a fine-tuned universe.

Dr. Carroll said he would stop defending his model now, and would instead defend Aguirre-Gratton.

Dr. Craig gave three reasons why the universe popping into being out of nothing requires a transcendent cause.

First, he said that nothing cannot cause anything to happen, because nothing is nothing.

Second, he said that if things pop into being out of nothing, then why don’t we see it happening all the time with other things.

Third, he said that we have no reason to dismiss the causal principle, especially when it is the basis of scientific inquiry and has been so fruitful in the progress of science.

Dr. Craig reiterated that baby universes in Carroll’s model would be dominated by Boltzmann brains, and we don’t observe that.

Dr. Craig said that even on the quantum gravity models that Carroll mentioned, there would still be a beginning.

Dr. Carroll said that Craig mustn’t say “popped into being” but instead that “there was a first moment of time”.

Dr. Carroll said that his model does indeed violate the second law of thermodynamics “YES!”.

At this point Carroll stopped talking about the topic of the debate and started expressing personal opinions about religion. It’s funny how often atheists do this in debates.

Dr. Carroll said that most theists don’t believe in God because of cosmology, but because of community and feelings.

Dr. Carroll said that science had learned a lot in the last 2000 years, so theism was false.

Dr. Carroll said that most philosophers don’t think that God exists, so theism was false.

Dr. Carroll said microscopes and telescopes were absent 2000 years ago, so theism was false.

Dr. Carroll said that religion should be about community and feelings, not about what is true.


My conclusion was that Carroll lost because he is just satisfied to throw theories out and not to argue that they are true by citing evidence. Carroll never seemed to be interested in finding out what is true, but instead he just wanted to tell a story that didn’t include God, and assert that by Occam’s Razor, his story was a better explanation. I am not impressed with theoretical speculations, although the layperson might be. I kept waiting for him to respond to Craig’s points about how his model was falsified by experimental evidence and observations, e.g. – the Boltzmann brains or the baby universe generation, and he never cited the evidence I wanted him to cite. Craig did have some evidence for his views, but he could have been stronger in making his case. He could have shown the e-mail from Vilenkin that stated that he had understood the BGV theorem, and was using it correctly, for example.

For me the winning side comes down to evidence. The standard model is the standard model because of scientific evidence. Until that evidence is overturned, then speculative models are of no interest to anyone who is evidence-driven. Speculations are not science. A philosophical presupposition of metaphysical naturalism is not science.

The nice thing is that Robin Collins, one of Craig’s respondents, went deep into the science of the fine-tuning, especially on one of my favorite data points, the cosmic microwave background radiation. The paper he presented is now posted on his web site (H/T Christian Apologetics Alliance). I posted about the CMBR before in my post about particle physicist Michael Strauss lecture on cosmology and fine-tuning at Stanford University and the his more recent lecture at the University of Texas. Note that Strauss is an experimental physicist, not a theoretical physicist like Carroll.

Here’s another review of the debate by Randy Everist of Possible Worlds blog. He explains the back-and-forth over Boltzmann brains and the BGV theorem in more detail.

19 thoughts on “Sean Carroll debates William Lane Craig on cosmology and God’s existence”

  1. At first, I was very much impressed with Carroll – I think due to style – but later on I felt that his was a “model of the gaps” faith. His naturalistic position was a given and he was willing to use any model, evidence-based or not to support this set position. No theistic explanation would ever work for him.


  2. Thanks for your round up, WK. I had been trying to find any review of the other talks by Rosenberg, Maudlin, Collins & Sinclair and Craig’s & Carroll’s responses to them. Any leads? I particularly enjoyed Jim Sinclair’s especially his rejoinder at the end. Again, thanks!


  3. The a-theists are all gaga over Carroll’s performance in this debate. They say that Carroll “destroyed” Craig, but of course they said the same thing about Hitchens. Many have said that Carroll “proved” that the beginning of the universe does not require a cause, but, of course, if Carroll “proved” anything of the sort, there would be statues of him throughout the a-theist world. (And, they would be regularly prayed to by the “freethinkers,” just like the Darwin statue.) Furthermore, Carroll would win so many “not-so-Nobel” prizes that he would have to donate them all to a museum for storage.


  4. I am an atheist. I wouldn’t say either side destroyed the other. Both held their own and it was a pretty close debate. I would give Craig a slight edge only because of his organization, which comes from having a lot of debating experience.


    1. That seems to be a really fair assessment. The atheists I know believe that this is the best that anyone has ever done against Craig – and I am inclined to believe that is reasonable, although I am partial to Craig as a theist.


      1. I haven’t taken the time to go through the entire debate, but from what I’ve seen, a lot of Carroll’s arguments seem to boil down to “if I were God, I would do it this way. But it’s not done this way, therefore God doesn’t exist.”

        As for Carroll doing the best against Craig, I would totally disagree. Keith Parsons did very well against Craig, and arguably, it’s the only debate that Craig has lost. Quentin Smith did a good job arguing against Craig during their debate, but it would’ve been better suited for a paper.

        Craig wins because he’s a tremendous debater, manages the clock well, and has fairly good arguments (although I’m not the biggest fan of the Kalam). Most of the people he debates against either a) don’t take theism seriously, b) are completely unprepared, or c) both.


        1. Thank you Paul – I will look up these other people you have mentioned. Can you explain to me why you do not like Kalam? Thanks!


          1. In response to both of you:

            WK: Yes, Craig has good evidence on his side for the Resurrection. I’m not in love with the KCA, for reasons I’ll expand upon below. He actually can play fairly well to the audience’s emotions (his debate with Wolpert was a great illustration of this), but generally refuses to do so. Finally, I would agree that there are some very qualified atheists he’s debated with. Hitchens, despite being fairly ignorant of history, was exceptional at appealing to people’s emotions. One could actually argue that appeal to emotion was what the New Atheists did best!

            WorldGoneCrazy: I think that premise 2 of the Kalam (KCA) is questionable. There are legitimate debates about the past eternity of the universe (I’m talking before the singularity). According to Aron Wall, however, the universe can’t be eternal at the quantum level. Of course, we don’t have a theory of quantum gravity, so it’s speculative. The other issue with the KCA is that one can argue it blurs the line between primary (divine) and secondary (i.e. natural) causality. That may be, however, due to how Craig will often defend it (using the BGV theorem and the like). Regardless, it’s certainly an interesting argument, and I love how many videos on YouTube try to “debunk” the KCA without actually understanding it. It’s actually a fairly complex argument; Craig just makes it seem very simple.

            All in all, the fact that Craig gets so much ridicule from the feebthought (freethought) segments of the internet indicates that he must be doing something right. I don’t agree with him on some of his theology, but I think he is an important intellectual nonetheless.


    2. I disagree. Carroll had nothing but a speculative model. He could not produce any evidence for the models. Then Craig introduced evidence that disproved his models empirically. Carroll’s response was to switch from his speculative model to another model not his own, and he couldn’t support that one. In a debate like this, I am looking for who has empirical evidence for his view.


      1. I disagree. Carroll had nothing but a speculative model. He could not produce any evidence for the models. Then Craig introduced evidence that disproved his models empirically.

        Carroll’s response was to switch from his speculative model to another model not his own, and he couldn’t support that one. In a debate like this, I am looking for who has empirical evidence for his view.

        Different physicists have different models, and physicists all agree that we are not sure which of the models is the right one. William Lane Craig cited a paper (not empirical evidence, but a theoretical argument) that MAY create problems for the model that Carroll once proposed. Carroll pointed out that there are other proposed models that don’t have the same issue. The fact that there is no evidence one way or another between these various models (and thus we cannot at the moment figure out which model is correct without better theoretical and empirical tools that are still being developed) does not mean the answer is “God did it!!!!”.


        1. Evidence for the standard Big Bang:
          Einstein’s theory of general relativity, and the scientific confirmation of its accuracy
          measurements of the cosmic microwave background radiation
          red-shifting of light from galaxies moving away from us
          radioactive element abundance predictions (from supernovae)
          helium/hydrogen abundance predictions (nuclear fusion)
          star formation and stellar lifecycle theories
          the second law of thermodynamics

          Evidence against the standard Big Bang:

          Evidence for speculative save-the-atheism model:

          Evidence against the speculative save-the-atheism model:
          Boltznmann Brains predicted, not observed
          Quantum gravity models still require a beginning

          We need to get down to specifics.


          1. I can see the beginning of the universe, the cosmic fine-tuning, the origin of life (proteins, etc), the resurrection, the galactic habitability, the stellar habitability, (deep breath, continues), the moral argument, the free will, the consciousness, the sudden origin of body plans in the Camnbrian explosion… (passes out from talking too long)… (wakes up) the veridical NDEs, studies on the efficacy of mental effort (Schwartz)… (mumbles more, inaudible) (passes out again).


  5. Why do atheists (professionals in their fields too) attempt to avoid God? Isn’t it pretty much obvious God exists?


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