Thursday, January 06, 2005

The Privileged Planet Part 1: Where Purpose and Natural Law freely Mix Part 1

Original publication

Guillermo Gonzalez, assistant professor in astronomy and fellow at the Center for (the Renewal of) Science and Culture of the Discovery Institute and Jay Richards, formerly a fellow in philosophy and theology and vice president and senior fellow at the Center for (the Renewal of) Science and Culture of the Discovery Institute recently published a book called "Privileged Planet" in which they argue for purpose in the Universe. Their arguments are very similar to those found in "Rare Earth" by Ward and Brownlee and for good reasons, Gonzalez used to work at the same University of Washington where Ward and Brownlee work and was closely involved in the development of their thesis an aspect I intend to further address in a future posting. The main difference between the two books is that in "Privileged Planet" the authors argue for 'purpose' based on the "Rare Earth" argument of probability and additionally a novel argument based on a correlation between habitability and measurability. The combination of low probability and specification (correlation) implies, using Dembski's “Design Inference”, design.

Gonzalez et al's presentation at the “Who is the Designer: Reasons to Believe 2003” conference was critically reviewed during the Conference at the American Scientific Affiliation 2003 Annual Meeting "The Heavens Declare the Glory of God". Kyler Kuehn presented a critical analysis of the Privileged Planet hypothesis (PPT).

In a series of "Privileged Planet" postings I intent to present, explore and critique their arguments.

In part 1 I describe a lecture by Gonzalez et al on April 8th 2004 in the Pacific Science Center in Seattle. A day earlier Gonzalez et al had presented their arguments at the University of Washington. Both events were co-sponsored by the Discovery Institute. I regret that I was not present during their presentation at the UW since it would be interesting to hear the opinions from astronomers and especially Ward and Brownlee.

Andrea Bottaro wrote some earlier comments on the Privileged Planet on this blog.

April 8, 2004 Pacific Science Center, Seattle presentation

I recently attended Gonzalez et al’s presentation at the Pacific Science Center in Seattle. An audience of close to 100 people attended this meeting. The president of the Pacific Science Center, Bryce Seidl, opened by saying that they had received much controversy over this presentation and ended by stating that the opinions of the presenters was not the opinion of the Pacific Science Center. It seems that they had received significant number of emails and phone calls on this controversial topic.

The presentation was not very different from the ASA presentation other than that the slides appeared to be slicker and they showed a preview of a 3-D simulation by the company that is producing a video to accompany their book: Illustra Media, well known for its work on Icons of Evolution and other Discovery Institute books. See NMSR website for some interesting connections between Illustra Media and Discovery Media.

Part 1 Jay Richards: Chance or Design>

The presentation started with Jay Richards who explained that the argument of purpose is based on a concept called ‘cumulative case evidence’. Others, more skeptical, may call this ‘cherry picking’. I did a search using Google and found that the “cumulative case argument” is commonly used in arguments for the existence of a God. In fact a “cumulative case evidence” approach seems to be suffering from a “God of the Gaps” argument. By itself the use of “cumulative case argument” cannot “prove” anything unless one works from the assumption that “God would create a habitable and measurable environment for His Creation only”. But that would seem to make the argument circular.

The “Privileged Planet” seems to be a response to the ‘Copernican principle’ that we “inhabit no unique place” or that the “earth is mediocre”. This observation can be turned into a metaphysical one such as done by Sagan. But I argue that similarly the claim of ‘purpose’ is a metaphysical claim.

If the ‘Privileged Planet’ were to limit itself to a critique of the metaphysical claims based on the ‘Copernican principle’ then I would not be here critiquing its claims.

Richards, continued to argue that although we have a sample size of one we can extend the argument to the whole universe through law like claims such as that life needs Carbon and Water. Carbon and Water are argued to have ‘special properties’ needed for life: Water is the ‘universal solvent’ and Water is liquid in the same range where Carbon chemistry is most active were proposed as important observations to support the claims. (Is this a correct claim? I will do some research to explore this in a later posting.) Interestingly enough Richards suggested that Silicon might be a plausible basis for life as well, but “that’s it”.

The ‘Privileged Planet’ argument is based on two pillars.

Improbability of habitability and measurability (complexity) and correlation between habitability and measurability (specification). In other words purpose or design is infered based on Dembski's Design Inference. Although Richards stated that they base their design inference also on the work of others, Dembski's gets the spotlight.

What is needed for a habitable planet? Requirements for habitability include a ‘Goldilocks zone’ in which planets can have liquid water (also known as the ‘circumstellar habitable zone’), a large size moon, a terrestrial planet and the right cosmic time (15 billion years). In addition the cosmos has to be ‘fine tuned for life’. So is this all chance or purpose? Notice that Richards argues for chance OR purpose, implicitly including regularity or necessity into ‘purpose’. In my discussions after the presentation, he repeated his claims. This seems to be a major weakness of their argument namely that law like processes can be the ‘designers’ of ‘purpose’. Or in other words, purpose can point to an external or internal teleology.

Since the universe has a lot of stars (10^23) it has a lot of ‘tries’ and thus anything improbable can happen. In addition it is hard to give exact probabilities to support their arguments. The editors of ‘Privileged Planet’ insisted on hard numbers but the authors declined. They do provide what they claim is a lower end probability based on the cumulative argument of 13 events with a probability of 10%. Or in other words, their argument is that the probability is less than 10^-13. Let me first point out that this argument has some problems. First of all not all of these probabilities are independent, second of all, not all of these probabilities may be accurate, and third of all, not all of these probabilities may be relevant. But even accepting their argument, with 10^11 starts in our galaxy and 10^11 galaxies, this makes for 10^9 instances.

So how do we find purpose? Probabilities are not enough, we need to show that habitability also provides for the best measurability. An example would be ‘perfect eclipses’.

Part 2 Guillermo Gonzalez: Correlation and specification

Gonzalez followed and explained how his trip to his first and only solar eclipse in India on October 24th 1995 had presented him with an almost spiritual experience. This was the first time he considered the link between habitability and measurability. Without doubt this eclipse left quite an impression on Gonzalez.

Gonzalez listed several examples of correlation between habitability and measurability but for the talk limited himself to two examples: 1. Solar eclipses and 2. Galactic Habitable Zones.

Solar eclipses are important for our understanding of the corona and the emission spectrum first observed by Young during a solar eclipse.

In addition, solar eclipses were important for the confirmation of the theory of relativity.

But science is opportunistic, and uses what is available to further its discovery. Without the solar eclipses we would perhaps never have known about the spectrum of the corona and thus never wondered about our lack of knowledge. This is called the ‘observer bias’. In case of Einstein's theory of relativity it is interesting to point out that the first confirmation was not the solar eclipse but rather the retrodiction of the precession of Mercury's perihelion. In part 2, I will explore these issues in more detail.

Gonzalez showed how within our solar system there is only one other planet where the apparent size of its moon and the sun are equivalent. But is a perfect match required for discovery or is a moon larger than the sun sufficient as well? And if the moon is so important for discovery, how come it has a ‘dark side’?

The question then raised by Gonzalez was: can this be explained in terms of laws of physics? Surprisingly Gonzalez argued that indeed laws of physics explain the correlation between habitability and measurability.

The next example was the Galactic Habitable Zone. First of all it is important to point out that the GHZ is biased towards the Earth. By necessity, the earth must be in the GHZ. The GHZ is characterized by at least two requirements, not too many threats (although Ward and Brownlee argue that such ‘threats’, which led to major extinctions, were important for the arrival of complex life.

Part 3 Jay Richards: Dembski's Design Inference

Jay Richards ended the presentation attempting to tie all these concepts together using Dembski’s Design Inference. Low probability of habitability and measurability combined with an (independent) specification (correlation between habitability and measurability indicates design.

The final picture was of an astronomical observatory on top of a mountain in Hawaii. When climbing up to the top we would all recognize the purpose of these telescopes perched on the top of this island.

Questions and answers

Only 10 minutes were left after the presentation for questions and answers, Gonzalez and Richards had a conference call with New Zealand. Bryce Seidl selected the various audience members with questions. His first selection was Mark/Martin Daniels who identified him as a member of the American Association of the Advancement of Science and member of PACSCI. He started off with quoting from the Wedge document and ended with the question “I have been encouraged by the staff (of the PACSCI) to ask you to the following question. Will you promise that you will not use this presentation at the Pacific Science Center in your marketing and publicity efforts’? Despite some upset shouts of “what’s your question?”, “get a life”, “loser”, he persisted. Gonzalez and Richards looked a unhappy and Richards got to address the question. Instead of answering the question, he accused the questioner of using an ‘ad hominem’ argument. Jay, who is a philosopher, should know better that a question is not necessarily an ‘ad hominem’ argument. What is ironic is that the Discovery Institute's response to the Wedge argues

Instead, they (Darwinist colleagues and some sympathizers have come to rely upon ad hominem attacks, motive mongering, conspiracy theories, guilt by association and other tactics of intimidation - thus distracting from a failing system of thought.

Now that is a perfect 'ad hominem' argument.

Another audience member asked, given that there are about 300 billion stars in our galaxy, how many of those fall within the Galactic Habitable Zone? A good question indeed. Gonzalez answered that, although he believes that the numbers will go down when new factors are taken into consideration, the number, which is supported by the 2004 paper by Lineweaver, suggests about 10%. That’s a lot of planets indeed.

"The Galactic Habitable Zone and the Age Distribution of Complex Life in the Milky Way", Charles H. Lineweaver, Yeshe Fenner & Brad K. Gibson, Published in Science Jan 2, 2004

The 68% contour contains less than ~10% of the stars ever formed in the Milky Way.

Another question was about the constancy of the speed of light. Young earthers may be disappointed by Gonzalez’s response that the data show that the speed of light has remained constant.

The next question was about the star formation rate. Are new stars still being formed. Another tricky question for young earthers.

The next question was about the size of the universe, is it closed, infinite? The response was unbounded but finite. This is a tricky concept indeed.


After the presentation I followed Richards up to the projector where Gonzalez was unhooking his Mac and asked him if he and Gonzalez would like to sign my book. I asked him a question about Dembski. If as Dembski argues the specification has to be independent from the event how come that when Gonzalez argued that it was natural law which explains the moon’s habitability and measurability correlation, that we can infer purpose? Richards seemed a bit taken back by the question; he seemed to suggest that unlike Dembski who considers chance and necessity, they consider necessity or natural law to be part of ‘purpose’. He stated that ‘this was a difficult concept not easily explained’. He emphasized that they were also not relying purely on Dembski’s arguments.

Gonzalez also seemed to retreat from his earlier position that life is improbable to complex life is improbable.

Gonzalez earlier had stated that

Are you in complete agreement with Ward and Brownlee’s hypothesis?

Gonzalez: I am not in complete agreement with a couple of aspects of their version of the Rare Earth hypothesis

First, I am more skeptical than Brownlee and Ward about the existence of simple life on other worlds. They seem to downplay the great difficulty origin-of-life researchers are having in understanding how life first arose from a naturalistic perspective.

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