Truly a gift that keeps giving, that Christmas Day article by Eric Metaxas in the Wall Street Journal continues to stir discussion and denunciation ("Science Increasingly Makes the Case for God"). The appetite for debate isn’t surprising, given that it’s reportedly the most popular article ever published by the online WSJ, with 361,467 Facebook "likes" when I looked. See my own take on it here, noting that Eric might have extended his design argument further, all the way from the macro to the micro scale ("Universe, Planet, Proteins…It’s Fine-Tuning All the Way Down").

Well, much of the critical "discussion" so far has been irrelevant, it seems to me: either atheist and other censors saying the newspaper should never have published the piece, or, from more thoughtful quarters, theological and philosophical beefs that don’t seem to understand Metaxas was fundamentally drawing a scientific design inference. To that, whether he’s right or wrong, theology and philosophy really have nothing to say. The science shows what it shows.

Nor is it germane to point out that Metaxas isn’t a scientist. He’s a layman presenting an argument based on science, to which a scientist or a non-scientist can respond as his own reason prompts. The "He’s not a scientist" complaint was heard from, among others, atheist and Dawkins sidekick Lawrence Krauss at Arizona State. But Dr. Krauss does stand out from the crowd for at least trying, in addition, to offer a rebuttal on the scientific merits.

He wrote a letter to the Wall Street Journal that wasn’t published, but you can read it at RichardDawkins.net. We’re not among those who would say that because we don’t agree with Krauss, it’s a good thing the Journal declined to publish his letter. On the contrary, he deserves a hearing and a reply.

I asked ENV‘s Daniel Bakken, author of our current series "Exoplanets," what he would say in a conversation with Krauss. What follows, serially, are the points made by Larry Krauss, followed by Dan Bakken’s response.

Krauss: We currently DO NOT know the factors that allow the evolution of life in the Universe.  We know the many factors that were important here on Earth, but we do not know what set of other factors might allow a different evolutionary history elsewhere.  The mistake made by the author is akin to saying that if one looks at all the factors in my life that led directly to my sitting at my computer to write this, one would obtain a probability so small as to conclude that it is impossible that anyone else could ever sit down to compose a letter to the WSJ.

Bakken: This reply does a great disservice to the science of astrobiology, which is trying to answer just this question. It IS the results of this branch of science that are forcing us to seriously examine the factors that can allow any conceivable form of complex life in the universe, but especially that which could allow for advanced technological civilizations. So we DO KNOW the minimum factors to allow life in this universe are greatly increasing. This is an incredibly weak first response when one knows the current state of the research.

Krauss: We have discovered many more planets around stars in our galaxy than we previously imagined, and many more forms of life existing in extreme environments in our planet than were known when early estimates of the frequency of life in the universe were first made.  If anything, the odds have increased, not decreased.

Bakken: Since when did astronomers seriously consider planets to be incredibly rare? We imagined there could be even more than we have found. This isn’t an argument. As far as life existing in extreme environments, that is still Earth-based life, and doesn’t necessarily say anything about the frequency of life outside our solar system. These extreme forms of life, so far as we can tell, are not capable of a technological civilization either. The argument isn’t about microbes, it’s about life forms that could visit us or at least communicate with us. That is what most people think about when they ask "Are we alone?" Or at the very least, other self-aware beings who also engage in philosophical ponderings about the meaning of life, or "Why are we here?" If anything, the odds have vastly decreased in my opinion, looking at the actual data.

Krauss: The Universe would certainly continue to exist even if the strength of the four known forces was different.  It is true that if the forces had slightly different strengths (but nowhere near as tiny as the fine-scale variation asserted by the writer) then life as we know it would probably not have evolved.  This is more likely an example of life being fine-tuned for the universe in which it evolved, rather than the other way around.

Bakken: Even with the most generous reading of Lawrence’s point here, there are only an extremely small fraction of conceivable universes that could allow complex molecules, especially ones as capable as our carbon-based molecules in this universe, compared to the theoretical number of possible universes. Yet we only have direct evidence of this universe, so we must answer the question "Why is this universe seemingly so fine-tuned that advanced technological civilizations are allowed?" Positing a near infinite number of other universes relaxes this tension, yet these are still beyond direct detection. At this point it is either faith in other universes, or faith in a creator that reasonably answers the impression of design.

In any event, while Dr. Krauss only mentions the four forces here, it isn’t just the values of those four that allow our universe to be life-friendly. It is their interconnected strengths, along with the physical laws and constants that also need to be incredibly fine-tuned.

Of the many fine-tuned features of our universe, just one, the mass density of the universe, which is set by the expansion rate of the universe, must be fine-tuned to the order of one part in 10⁶⁰.  This is an incredibly small number. The diameter of the observable universe is 27.6 billion light years. That is about 2.6X10²⁹ millimeters. One millimeter compared to the diameter of the universe is still incomprehensibly larger than this one fine-tuned parameter, of one part in 10⁶⁰! So, yes, the fine-tuning of the universe is unbelievable, and this drives those who are non-theists to the imagined safety of a multiverse with a near infinite number of universes, against the direct evidence of only our own.

Krauss: My ASU colleague Paul Davies may have said that "the appearance of design is overwhelming," but his statement should not be misinterpreted.  The appearance of design of life on Earth is also overwhelming, but we now understand, thanks to Charles Darwin, that the appearance of design is not the same as design, it is in fact a remnant of the remarkable efficiency of natural selection.

Bakken: This is misdirection. We are trying to grapple with the question of this universe’s fine-tuning, and pointing to the design of biological systems doesn’t address the point at all. Davies made this statement in the context of the physical laws of the universe, and its life-allowing properties, so he isn’t being misinterpreted by Metaxas. Again, I am struck by the weakness of Dr. Krauss’s response here. He certainly is smart enough to know he isn’t answering the question posed by Metaxas, a question that is in Dr. Krauss’s own field of expertise. In fact, the design in biology, even if it is natural, only adds to the mystery of why the only universe we have direct knowledge of has the properties of fine-tuning that can allow these processes. Just saying we wouldn’t be here to notice it, as Dr. Krauss implies, isn’t an answer either.

Even beyond that is the uniqueness of the Earth when comparing it to the many other planetary systems that are being discovered. It takes an impressively stable climate over billions of years, all the while protected from gravitational and life-extinguishing radiation disturbances, to make our home what it is. The solar system, the Sun, the other planets’ orbits and characteristics, the moon, even our galaxy and our place in it — all these contribute to what is seen by a growing number of researchers in the field as pointing to the fact that the Earth is not an average planet, but an incredibly special one.

"When one knows the data, his response is pretty weak, but the best possible," says Bakken. "It shows the hallmarks of defending a losing argument." Agreed.

Image source: Carlos Goul�o /Flickr.