Tag Archives: Luke Barnes

Cosmologist Luke Barnes answers 11 objections to the fine-tuning argument

This is from the blog Common Sense Atheism. (H/T Allen Hainline)

Atheist Luke Muehlhauser interviews well-respect cosmologist Luke Barnes about the fine-tuning argument, and the naturalistic response to it.

Luke M. did a good job explaining what was in the podcast. (I wish more people who put out podcasts would do that).


In one of my funniest and most useful episodes yet, I interview astronomer Luke Barnes about the plausibility of 11 responses to the fine-tuning of the universe. Frankly, once you listen to this episode you will be better equipped to discuss fine-tuning than 90% of the people who discuss it on the internet. This episode will help clarify the thinking of anyone – including and perhaps especially professional philosophers – about the fine-tuning of the universe.

The 11 responses to fine-tuning we discuss are:

  1. “It’s just a coincidence.”
  2. “We’ve only observed one universe, and it’s got life. So as far as we know, the probability that a universe will support life is one out of one!”
  3. “However the universe was configured, evolution would have eventually found a way.”
  4. “There could be other forms of life.”
  5. “It’s impossible for life to observe a universe not fine-tuned for life.”
  6. “Maybe there are deeper laws; the universe must be this way, even though it looks like it could be other ways.”
  7. “Maybe there are bajillions of universes, and we happen to be in one of the few that supports life.”
  8. “Maybe a physics student in another universe created our universe in an attempt to design a universe that would evolve intelligent life.”
  9. “This universe with intelligent life is just as unlikely as any other universe, so what’s the big deal?”
  10. “The universe doesn’t look like it was designed for life, but rather for empty space or maybe black holes.”
  11. “Fine-tuning shows there must be an intelligent designer beyond physical reality that tuned the universe so it would produce intelligent life.”

Download CPBD episode 040 with Luke Barnes. Total time is 1:16:31.

I’m going to put the list of resources for the podcast that Luke M. mentioned in his post, but without the actual hyperlinks. It saves me having to type up a summary. If you want to click the links that I removed, go over to Common Sense Atheism and the links are there.

Links for things we discussed:

  • Fine-tuned universe
  • Cosmological constant
  • Miss Marple
  • Other forms of life and Daleks
  • Elliot Sober
  • Cosmic inflation
  • The graceful exit problem
  • Carr and Rees, “The Anthropic Cosmological Principle and the Structure of the Physical World” (1979)
  • David Lewis’ modal realism
  • Boltzmann’s multiverse
  • Roger Penrose argues that some modern multiverse theories face the same problem that Boltzmann’s multiverse faces in The Road to Reality.
  • Everett’s multiverse
  • Wheeler – At Home in the Universe
  • Thorne-Hawking-Preskill bet
  • Edward Robert Harrison
  • Luke responds to PZ Myers
  • You can find some good talks by Polkinghorne and Ellis on fine-tuning at the Faraday Institute’s multimedia page.
  • William Lane Craig, “Design and the Anthropic Fine-Tuning of the Universe“
  • Robin Collins, “The Teleological Argument“
  • Good stuff: Davies – The Goldilocks Enigma; Rees – Just Six Numbers; Barrow – The Constants of Nature; Barrow & Tipler – The Anthropic Cosmological Principle; Leslie – Universes; George Ellis articles.
  • Fred Adams and Luke’s critique
  • Luke’s critique of Hector Avalos
  • Luke’s critique of Victor Stenger: part 1 and part 2
  • Luke’s critique of Hugh Ross
  • Luke’s critique of William Lane Craig: part 1 and part 2

I thought the funniest part was the Natalie Portman part. Boy, do I wish more atheists would listen to this podcast and understand what the fine-tuning argument is actually about. Luke M. gave Luke B. a ton of time to talk. There is a very good explanation of some of the cases of fine-tuning that I talk about most on this blog – the force of gravity, the strong force, etc. as well as many other examples. Dr. Barnes is an expert, but he is also very very easy to listen to even when talking about difficult issues. Luke M. is very likeable as the interviewer.

Do most cosmologists accept the reality of the cosmic fine-tuning?

I don’t know how I missed this, but apparently Dr. Richard Carrier, a historian, wrote a critique of the fine-tuning argument a while back, and Dr. Luke Barnes, a cosmologist responded to him.

Much of what is said by both of them in their contributions is beyond me, but I did want to quote one part from a blog post by Luke Barnes about whether most scientists accept that our universe is finely-tuned for complex embodied life.

First, Dr. Carrier writes this:

[Dr. William Lane Craig] claims “the fundamental constants and quantities of nature must fall into an incomprehensibly narrow life-permitting range,” but that claim has been refuted–by scientists–again and again. We actually do not know that there is only a narrow life-permitting range of possible configurations of the universe. As has been pointed out to Craig by several theoretical physicists (from Krauss to Stenger), he can only get his “narrow range” by varying one single constant and holding all the others fixed, which is simply not how a universe would be randomly selected. When you allow all the constants to vary freely, the number of configurations that are life permitting actually ends up respectably high (between 1 in 8 and 1 in 4: see Victor Stenger’s The Fallacy of Fine-Tuning).

And Dr. Barnes replies (in part): (links removed)

I’ve said an awful lot in response to that paragraph, so let’s just run through the highlights.

  • “Refuted by scientists again and again”. What, in the peer-reviewed scientific literature? I’ve published a review of the scientific literature, 200+ papers, and I can only think of a handful that oppose this conclusion, and piles and piles that support it. Here are some quotes from non-theist scientists. For example, Andrei Linde says: “The existence of an amazingly strong correlation between our own properties and the values of many parameters of our world, such as the masses and charges of electron and proton, the value of the gravitational constant, the amplitude of spontaneous symmetry breaking in the electroweak theory, the value of the vacuum energy, and the dimensionality of our world, is an experimental fact requiring an explanation.” [emphasis added.]

  • “By several theoretical physicists (from Krauss to Stenger)”. I’ve replied to Stenger. I had a chance to talk to Krauss briefly about fine-tuning but I’m still not sure what he thinks. His published work on anthropic matters doesn’t address the more general fine-tuning claim. Also, by saying “from” and “to”, Carrier is trying to give the impression that a great multitude stands with his claim. I’m not even sure if Krauss is with him. I’ve read loads on this subject and only Stenger defends Carrier’s point, and in a popular (ish) level book. On the other hand, Craig can cite Barrow, Carr, Carter, Davies, Deutsch, Ellis, Greene, Guth, Harrison, Hawking, Linde, Page, Penrose, Polkinghorne, Rees, Sandage, Smolin, Susskind, Tegmark, Tipler, Vilenkin, Weinberg, Wheeler, and Wilczek. (See here). With regards to the claim that “the fundamental constants and quantities of nature must fall into an incomprehensibly narrow life-permitting range”, the weight of the peer-reviewed scientific literature is overwhelmingly with Craig. (If you disagree, start citing papers).

There’s more, too.

I wish I understood cosmology enough to understand everything Dr. Barnes says, but it seems to me that this much is clear. If you’re an atheist and you’re reading stuff by these very far-out atheists, then you need to be very careful. Dr. Stenger and Dr. Carrier are both highly-intelligent and have great credentials, but it’s probably better for all of us to be interacting with the other side when we form our worldviews.

I noticed that respected atheist Jeff Lowder has a post up where he looks at both sides and comes down more with Barnes than with Carrier.

Luke Barnes reviews Victor Stenger’s critique of cosmic fine-tuning

Victor Stenger is a famous “Internet Infidel” atheist, but what makes him different is that he is has a PhD in physics. He wrote a book published by the atheist publisher Prometheus Press where he explains why he thinks that the universe is not fine-tuned for embodied sentient life.

An Australian physicist named Luke Barnes decided to write a response to his book, and the response is summarized (without the math!) on Uncommon Descent. Barnes has a PhD in Astronomy from Cambridge. He did postdoctoral research in Switzerland at the Institute for Astonomy, and now he is doing more postdoctoral research at the University of Sydney . The response that he wrote does not talk about God, or explanations of why the fine-tuning happened. I have no idea where his convictions are on any of that, because his response just talks about the fine-tuning itself from a scientific point of view.

Here’s how Uncommon Descent explains Barnes’ response.


Professor Victor Stenger is an American particle physicist and a noted atheist, who popularized the phrase, “Science flies you to the moon. Religion flies you into buildings”. Professor Stenger is also the author of several books, including his recent best-seller, The Fallacy of Fine-Tuning: How the Universe is Not Designed for Humanity (Prometheus Books, 2011). Stenger’s latest book has been received with great acclaim by atheists: “Stenger has demolished the fine-tuning proponents,” writes one enthusiastic Amazon reviewer, adding that the book tells us “how science is able to demonstrate the non-existence of god.”

Well, it seems that the great Stenger has finally met his match. Dr. Luke A. Barnes, a post-doctoral researcher at the Institute for Astronomy, ETH Zurich, Switzerland, has written a scathing critique of Stenger’s book. I’ve read refutations in my time, but I have to say, this one is devastating.

In his paper, Dr. Barnes takes care to avoid drawing any metaphysical conclusions from the fact of fine-tuning. He has no religious axe to grind. His main concern is simply to establish that the fine-tuning of the universe is real, contrary to the claims of Professor Stenger, who asserts that all of the alleged examples of fine-tuning in our universe can be explained without the need for a multiverse.

Dr. Barnes’ ARXIV paper, The Fine-Tuning of the Universe for Intelligent Life (Version 1, December 21, 2011), is available online, and I shall be quoting from it below. Since the paper is quite technical at times, I’ve omitted mathematical equations and kept the references to physical parameters to a minimum, since I simply wish to give readers an overview of what Dr. Barnes perceives as the key flaws in Professor Stenger’s book.

First, the abstract:

The fine-tuning of the universe for intelligent life has received a great deal of attention in recent years, both in the philosophical and scientific literature. The claim is that in the space of possible physical laws, parameters and initial conditions, the set that permits the evolution of intelligent life is very small. I present here a review of the scientific literature, outlining cases of fine-tuning in the classic works of Carter, Carr and Rees, and Barrow and Tipler, as well as more recent work. To sharpen the discussion, the role of the antagonist will be played by Victor Stenger’s recent book The Fallacy of Fine-Tuning: Why the Universe is Not Designed for Us. Stenger claims that all known fine-tuning cases can be explained without the need for a multiverse. Many of Stenger’s claims will be found to be highly problematic. We will touch on such issues as the logical necessity of the laws of nature; objectivity, invariance and symmetry; theoretical physics and possible universes; entropy in cosmology; cosmic inflation and initial conditions; galaxy formation; the cosmological constant; stars and their formation; the properties of elementary particles and their effect on chemistry and the macroscopic world; the origin of mass; grand unified theories; and the dimensionality of space and time. I also provide an assessment of the multiverse, noting the significant challenges that it must face. I do not attempt to defend any conclusion based on the fine-tuning of the universe for intelligent life. This paper can be viewed as a critique of Stenger’s book, or read independently.

Here’s a quote that I wanted to put out there from the paper about how widely accepted fine-tuning is among scientists:

There are a great many scientists, of varying religious persuasions, who accept that the universe is fine-tuned for life, e.g. Barrow, Carr, Carter, Davies, Dawkins, Deutsch, Ellis, Greene, Guth, Harrison, Hawking, Linde, Page, Penrose, Polkinghorne, Rees, Sandage, Smolin, Susskind, Tegmark, Tipler, Vilenkin, Weinberg, Wheeler, Wilczek. They differ, of course, on what conclusion we should draw from this fact. Stenger, on the other hand, claims that the universe is not fine-tuned.

That is a very diverse list. I know that Sandage, Ellis, Page, Tipler and Polkinghorne are theists. But I also know that Weinberg, Rees, Hawking, Greene, and Dawkins are atheists. So scientists all across the spectrum of worldview admit that the fine-tuning is real.

Now, let’s look at Barnes’ paper and see why Victor Stenger disagrees with the view of those scientists.

1) Stenger doesn’t show why the entropy at the beginning of the universe isn’t a case of fine-tuning:


We turn now to cosmology. The problem of the apparently low entropy of the universe is one of the oldest problems of cosmology. The fact that the entropy of the universe is not at its theoretical maximum, coupled with the fact that entropy cannot decrease, means that the universe must have started in a very special, low entropy state. (p. 23)

Let’s return to Stenger’s proposed solution… Stenger takes it for granted that the universe is homogeneous and isotropic. We can see this also in his use of the Friedmann equation, which assumes that space-time is homogeneous and isotropic. Not surprisingly, once homogeneity and isotropy have been assumed, Stenger finds that the solution to the entropy problem is remarkably easy.

We conclude that Stenger has not only failed to solve the entropy problem; he has failed to comprehend it. He has presented the problem itself as its solution. Homogeneous, isotropic expansion cannot solve the entropy problem – it is the entropy problem. Stenger’s assertion that “the universe starts out with maximum entropy or complete disorder” is false. A homogeneous, isotropic spacetime is an incredibly low entropy state. Penrose (1989) warned of precisely this brand of failed solution two decades ago... (p. 26)

2) Stenger responds to calculations showing the need for fine-tuning by speculating that future calculations will overturn the ones we have now:

The Cosmological Constant, Lambda

The cosmological constant problem is described in the textbook of Burgess & Moore (2006) as “arguably the most severe theoretical problem in high-energy physics today, as measured by both the difference between observations and theoretical predictions, and by the lack of convincing theoretical ideas which address it”. A well-understood and well-tested theory of fundamental physics (Quantum Field Theory – QFT) predicts contributions to the vacuum energy of the universe that are [approx.] 10^120 times greater than the observed total value. Stenger’s reply is guided by the following principle:

Any calculation that disagrees with the data by 50 or 120 orders of magnitude is simply wrong and should not be taken seriously. We just have to await the correct calculation. [FOFT p. 219]

This seems indistinguishable from reasoning that the calculation must be wrong since otherwise the cosmological constant would have to be fine-tuned. One could not hope for a more perfect example of begging the question. More importantly, there is a misunderstanding in Stenger’s account of the cosmological constant problem. The problem is not that physicists have made an incorrect prediction. We can use the term dark energy for any form of energy that causes the expansion of the universe to accelerate, including a “bare” cosmological constant (see Barnes et al., 2005, for an introduction to dark energy). Cosmological observations constrain the total dark energy. QFT [quantum field theory – VJT] allows us to calculate a number of contributions to the total dark energy from matter fields in the universe. Each of these contributions turns out to be 10^120 times larger than the total. There is no direct theory-vs.-observation contradiction as one is calculating and measuring different things. The fine-tuning problem is that these different independent contributions, including perhaps some that we don’t know about, manage to cancel each other to such an alarming, life-permitting degree. This is not a straightforward case of Popperian falsification. (pp. 34-35)

3) Stenger doesn’t consider the full range of values when deciding if something is fine-tuned or not:

Protons, Neutrons, Electrons

We turn now to the relative masses of the three most important particles in our universe: the proton, neutron and electron, from which atoms are made. Consider first the ratio of the electron to the proton mass, … of which Stenger says: “…we can argue that the electron mass is going to be much smaller than the proton mass in any universe even remotely like ours.” [FOFT p. 164] (p. 50)

The fact that Stenger is comparing the electron mass in our universe with the electron mass in universes “like ours” is all the evidence one needs to conclude that Stenger doesn’t understand fine-tuning. The fact that universes like ours turn out to be rather similar to our universe isn’t particularly enlightening. (p. 50)

Finally, and most importantly, note carefully Stenger’s conclusion. He states that no fine-tuning is needed for the neutron-proton mass difference in our universe to be approximately equal to the up quark-down quark mass difference in our universe. Stenger has compared our universe with our universe and found no evidence of fine-tuning. There is no discussion of the life-permitting range, no discussion of the possible range of [mass(neutron) – mass(proton)] (or its relation to the possible range of [mass(down quark) – mass(up quark)], and thus no relevance to fine-tuning whatsoever. (p. 51)

Those are just a few of the examples in the paper, highlighted in the Uncommon Descent article (emphasis theirs).

UPDATE: Commenter Eugene advises me that Barnes’ paper has now been published in a peer-reviewed journal. The journal is published by Cambridge University.

After action reports from William Lane Craig vs Lawrence Krauss debate in Sydney

The first one is from blogger Stephen of ChristianFaith.com. (H/T Apologetics 315)


William Lane Craig (WLC) attempted to deal with the main topic along classic logic paradigms (too much in my view), but Krauss (at times) was simply spoiling the dialogue with constant interruptions and diversions. In other words, he chose not to fight fair and intentionally landed some low blows.

[…]After that he gave us a useful dumbed-down materialist version of how the universe came into existence from ‘nothing’ and attacked Craig’s model for a transcendent beginning to the universe(s). An odd analogy (a reference to homosexuality) was used to counter Craig’s Kalaam cosmological argument but his 15 minutes were, overall, engaging, well-paced and entertaining. His personal style of humour was critical to his presentation as he freely admits that scientists within his own discipline of physics are often regarded as ‘obnoxious’ (his word, not mine).

In short, Krauss was confident, engaging, cocky and unconvincing re: the actual topic – ‘Why is there something rather than nothing?’

Craig’s 15 minutes were a direct contrast to Krauss’s.

Craig relied on his written notes far more heavily than the free flowing style of Krauss and he presented his views on the topic with intense logic and refined public speaking skills. His constant reference to the Leibnizian cosmological argument firmly imprinted in my mind that Craig was firmly committed to the central topic and he did his expert best to convince us of it. For example, Krauss’s various concepts of ‘nothing’ has been the subject to much derision by some (not just theists) and Craig deliberately exposed Krauss’s inconsistencies by quoting Krauss himself! For example:

  • “There are a variety of forms of nothing, they all have various definitions.”
  • “The laws of quantum mechanics tells us that nothing is unstable.”
  • “Nothing weighs something.”
  • “Nothing is almost everything.”

And this is where Krauss’s biggest problem lay. It’s his definition, ultimately, of ‘nothing’. Craig exposed the issue in just one slide and even Krauss looked uncomfortable in his chair as the quotes above were read out.

Which brings me to the next point, which for some of you will seem quite trivial.

I was seated close to the stage and had a great view of Krauss the man. I watched him closely as Craig presented his views and was very disappointed to see some of his reactions that I would describe as just plain rude. Without a buzzer this time, Krauss was constantly either rolling his eyes in disapproval at some of Craig’s statements or even raising his hands at times to publicly announce his disapproval.

Why do this? One can only interpret this as arrogance and rudeness. I could not imagine Craig himself or Ravi Zacharias or John Lennox adopting these negative (look-at-me-folks) non-verbal gestures.

Stephen then links to a reaction to the debate from physicist Luke Barnes, whose preview of the debate I blogged about before.

The review is in a comment by Dr. Barnes:

It went alright, I think. A little too much interruption, and some red-herrings from the moderator, but reasonably civil and on-topic.

The most interesting bit came when Craig was trying to justify premise 2 of his argument:

“If the universe has an explanation, then that explanation is God.”

Krauss disputed this premise in the opening speech, saying that it just assumed God did it. Craig’s argument for premise 2 went something like this:

A. Definition: the universe is the totality of physical reality. (Call it the multiverse if you like, if there is one.)
B. Then, if the universe has an explanation, it cannot be in terms of physical things.
C. Since the universe includes all matter, energy, space and time, the explanation must then be a transcendent, immaterial, spaceless and timeless entity.
D. The only thing that Craig can think of that can be a cause whilst being immaterial is an unembodied mind.
E. Thus, if the universe has an explanation, then that explanation is a transcendent, immaterial, spaceless and timeless mind. That being deserves the title “God”.

Krauss responded by questioning the definition. He tried to get Craig to say that physical reality was just everything in spacetime, since then he could say that science can talk about spacetime foams and other postulated physical things more fundamental than spacetime. I think, given more time to clarify, Craig would have said that spacetime foam is a physical thing (since it can appear in physical theories) so its part of the universe.

Krauss also responded that D merely states the limit of the human mind, and says nothing about reality. Craig could have responded by asking for an alternative, or rephrased the argument as an inference to the best explanation. I think that “the only hypotheses I can think of” type assumptions are lurking behind almost all inferences. (Maybe I can show that from Bayes theorem. I’ll have a think about that.).

This was the most relevant bit of the debate, but then things got sidetracked (I think because of the moderator).

I replied to Dr. Barnes on his blog like this:

I think that Dr. Craig is leaving it to his opponent to present and defend alternatives to his views. It’s not his job in the time he has to present alternatives and refute. That’s the job of his opponent. Dr. Peter Millican did a good job of doing that in his debate with Dr. Craig, and Dr. Craig had to defend and refute the alternatives that Dr. Millican presented.

Thanks for your comments, Dr. Barnes. I linked to your preview and to this review of the debate as well.

Not sure if I want to spend the time summarizing these debates. It’s a joy to summarize a debate with Austin Dacey, or Walter Sinnott-Armstrong or Peter Millican, but Dr. Krauss is not in that class of debaters. But I think these debates are useful to show the fundamental unattractiveness of atheism as a worldview. I don’t want to be anti-reality like Dr. Krauss – always taking refuge in speculations and hiding from scientific evidence in order to keep up the delusion for as long as possible.

Physicist Luke Barnes previews Craig-Krauss debate in Sydney, Australia

First, a preview of the Craig-Krauss debate that took place yesterday from Sydney-based philosopher Luke Barnes, whom I’ve written about before.


Krauss is in Sydney to debate the question “Why is there something rather than nothing?” – the traditional starting point for an ancient argument for the existence of God. Kraus, of course, is a cosmologist, known in the field for his work on the cosmological constant and dark matter, and to the wider public for books such as The Physics of Star Trek and A Universe from Nothing. Krauss’s opponent is the Christian philosopher William Lane Craig. He has built a career around the philosophical defence of theism, and is best known outside academia for his many public debates with atheists.

I am, like Krauss, a professional cosmologist and astrophysicist. I’ve also interacted with a philosopher or two, and I’ve read a lot of Craig’s work. So I thought it might be opportune to offer a guide to the uninitiated.

[…]Krauss’s latest book claims that advances in science have shown that we can answer the question “why is there something rather than nothing?” without invoking God. His argument can be summarised as follows:

  1. The basic stuff of the universe, as we now understand it, consists of matter and energy, space and time, governed by laws of nature.
  2. Particles of matter correspond to certain configurations of quantum fields. There is a configuration that corresponds to no particles (the “vacuum”). A state with no particles can evolve into a state with particles. Thus, matter can appear from no-matter.
  3. The universe as a whole may have zero net energy.
  4. There are theories that suggest that that space and time themselves are not fundamental, but emerge from a state without space and time.
  5. The laws of nature may be stochastic and random, in which case there may be no ultimate laws of nature.
  6. Since we can imagine the universe coming from a state with no matter, no particles, no space, no time and no laws, something can come from nothing.

Krauss’s book was far from universally acclaimed. Fellow unbeliever and physicist-turned-philosopher David Albert wrote a scathing review for the New York Times. Krauss responded by calling Albert “moronic” and generally dismissing philosophy as a waste of time. I’d love to stick up for a fellow cosmologist, but I’m with Albert and my reasons mirror his.

Fundamental physics is, always has been and – unless it undergoes a major identity crisis – always will be about what the basic stuff of the universe is and how it interacts and rearranges. There is nothing deeper. Thus, there can be no answer within science as to where that stuff came from, why it is that type of stuff, why it obeys laws, why those laws, or why there is anything at all. All scientific explanations stop at the basic stuff.

This is why Krauss’s argument fails. Particles can appear from no-particles, not from nothing. The underlying field is always there. A state with zero energy is not nothing. There must first be a thing before we can measure its energy, even if the number we get is zero. A physical state with no space or time, however strange, is still not thereby nothing. A universe with laws that vary from place to place and time to time is clearly not the same as one with no laws at all. It just makes the laws more complicated. Step 6 makes an unjustified leap from “something from not-these-five-things” to “something from nothing.”

There must always be questions that science leaves unanswered. Naturalism posits that there is nothing but the stuff of science. Here, then, is the challenge for naturalism. To believe naturalism, one must believe that these questions are unanswerable. Not just unanswered, not just awaiting a breakthrough, not just an open research question. They must be non-questions, meaningless strings of words, nonsense cleverly disguised as the oldest and deepest questions mankind has asked about reality. Unfortunately for Krauss, to have any hope of doing that he’s going to need to put on his philosopher’s hat.

Dr. Craig posted his comments about the debate after it happened:

The dialogue last night with Krauss went really well! We largely avoided the personal attacks and finally focused on the philosophical issues. Krauss did not mount much of a defense of his claim that physics can offer plausible explanations of why something exists rather than nothing and did not seem to understand Leibniz’s argument, taking it to be about the temporal origin of he universe. Now on to Melbourne, where the dialogue will be moderated by none other than Graham Oppy!

You can also find a full review of the debate by someone who attended it here.


Krauss decided not to primarily attack the premises of the contingency argument but rather the very nature of deductive syllogisms. To do this he presented the following syllogism (I admittedly did not get to write this down but this was the general idea):

  1. Mammals practice homosexuality.
  2. Craig is a mammal
  3. Therefore Craig practices homosexuality. (I honestly can’t remember the exact phrasing of the conclusion but you can see the general gist)

This shocked me. Not only was it an obviously invalid argument but it got a big laugh from the audience (who didn’t seem to see how bad it was). To Krauss’ credit he did at least say that the conclusion was obviously false (at least to his knowledge) but it struck me as very disrespectful. Krauss complimented Craig on being a genuinely nice guy but continued to make regular quips about his use of deductive logic and lack of intellectual honesty. He also attacked the second premise of the argument as obviously question begging.

Krauss concluded his last minute with personal E-mail correspondence between himself and Alexander Vilenkin concerning the Borde-Guth-Vilenkin theorem, a piece of evidence that Craig often employs to demonstrate that the universe began to exist. Unfortunately there was a lot of text on the slide but the main point from Vilenkin seemed to be that the BVG theorem could break down if it turned out that a quantum theory of gravity held to be true. I look forward to this letter becoming public so we can have a better look at it. I was disappointed that Krauss did not raise this earlier or spend more time explaining it. Krauss appealed to evolution, the multiverse and the appearance of apparent “poor tuning” as a way of defeating the teleological argument. Clearly Krauss was conflating the teleological argument from cosmology with some sort of intelligent design argument for biological complexity; a forgivable error for a layperson but not someone of Krauss’ stature.

I am praying that Dr. Craig is able to help Dr. Krauss consider the existence of God respectfully and fairly, and I hope you will as well. I do admire Krauss for agreeing to have these debates. He’s not just having one debate or two debates, but several. And this is not the first time he’s debated Dr. Craig either. You have to admire the man’s willingness to defend his views. I think a lot of atheists in the universities are insulated from arguments like Dr. Craig’s, and they’ll stay insulated form them unless them make an effort to hear the other side.