Book: Rare Earth: Why Complex Life is Uncommon in the Universe

[TimM]

In this thread, jason_t mentioned the book Rare Earth: Why Complex Life is Uncommon in the Universe, by Peter Ward and Donald Brownlee. I decided to read this book and post a review and critique of the "Rare Earth Hypothesis".

Anyone with an interest in the history of our planet should enjoy reading this book, even if one does not agree with the conclusions. Note that while at least one other author has taken the Rare Earth Hypothesis and turned it into an argument in favor of intelligent design, there is no mention of this in Rare Earth. There is, however, an article for sale on Amazon.com suggesting that "the authors were influenced by an individual with a strong 'Earth-is-unique' religious views". I have chosen not to read this article before forming my own opinion. In any case, this is not the right way to go about refuting a hypothesis. It is better to attack the authors' arguments, rather than their motivations for making those arguments.

No matter how rare the conditions allowing complex life prove to be, this alone can never be an argument in favor of intelligent design. Those conditions have to exist for anyone to actually notice. That we notice them here on Earth tells us nothing beyond the fact that those conditions are possible.

So that I don't have to do it all at once, I plan on making additional posts to this thread responding to some of the "Rare Earth Factors" - conditions the authors suggest are both rare and necessary for complex multi-cellular life to form. My general opinion is that while some of these concerns are valid, many of the factors may be neither as rare nor as necessary as the authors imply.

[TimM]

The Drake Equation

Ward and Brownlee provide an alternative version of the Drake Equation, modified to estimate the number of planets in this galaxy currently inhabited by complex multi-cellular (metazoan) life.

Their modified equation is as follows:

"N* x fp x fpm x ne x ng x fi x fc x fl x fm x fj x fme = N

where:

N* = stars in the Milky Way galaxy
fp = fraction of stars with planets
fpm = fraction of metal-rich planets
ne = planets in a star's habitable zone
ng = stars in a galactic habitable zone
fi = fraction of habitable planets where life does arise
fc = fraction of planets where complex metazoans arize
fl = percentage of a lifetime of a planet that is marked by the presence of complex metazoans
fm = fraction of planets with a large moon
fj = fraction of solar systems with Jupiter-sized planets
fme = fraction of planets with a critically low number of mass extinction events"

First of all, this equation contains numerous errors and redundancies in its terms. For example, "stars in a galactic habitable zone" should be a fraction, and it should be something like "fraction of those planets orbiting stars in a galactic habitable zone". Each term needs to reference all of the terms before it in some way, like the terms given in the original Drake Equation. Even after these errors are corrected, there is still an additional logical error.

The authors state that "as any term in such an equation approaches zero, so too does the final product." But this is only valid as far as each condition specified is absolutely necessary for complex life. In reality, each term should be modified by the chance that complex life can form without that feature. For example, "fm = fraction of planets with a large moon" should be replaced by something like:

(fm + fm' x (1 - fm))

where fm' = the fraction of planets without a large moon that can develop complex metazoans. Since fm and fm' must always be between zero and one, this term can never be less than fm' even if fm approaches zero.

The equation with each term modified in this way now takes into account the chance that the authors' proposed requirements for complex life are not absolute. Now it is more than a simple matter of proving that one of the terms approaches zero in order to claim that complex life is rare.

[Aytumious]

[ QUOTE ]

No matter how rare the conditions allowing complex life prove to be, this alone can never be an argument in favor of intelligent design. Those conditions have to exist for anyone to actually notice. That we notice them here on Earth tells us nothing beyond the fact that those conditions are possible.


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This is the point that IDers either fail to acknowledge or cannot comprehend.

[imported_luckyme]

[ QUOTE ]
No matter how rare the conditions allowing complex life prove to be, this alone can never be an argument in favor of intelligent design. Those conditions have to exist for anyone to actually notice. That we notice them here on Earth tells us nothing beyond the fact that those conditions are possible.

[/ QUOTE ]

That'll be a nice challenge to take on, enjoy. You've summed up the hurdle right here though. A meteorite came thru my roof, smashed thru the light bulb, bouced off a door hinge, went thru the oak bookcase, penetrated a book and stopped just touching the words "lucky me". If any of 1,000's of conditions it had encountered were slightly different, it would have stopped somewhere else, if it even hit earth. Thicker oak, lower hinge, bigger light bulb, cooler day, etc. How could that ever prove 'purpose' or 'intent'? Iow, it has to stop somewhere.

luckyme

[TimM]

[ QUOTE ]
That'll be a nice challenge to take on, enjoy.

[/ QUOTE ]

Actually I have no intention of taking it on any further in this thread.

Correct.
The last point is the part I am failing ro acknowledge or cannot comprehend.

"That we notice them here on Earth tells us nothing beyond the fact that those conditions are possible."

I think the conditions present on Earth can tell us a lot more than just that they're possible. This seems like a big cop out to me.

by looking at the finished product we can gather certain things about it. This is the same for all products that have been intelligently designed. You wouldn't accept that a car just fell together, you know that it was designed. Well, the the odds against a car forming are far higher than intelligent life forming from dumb matter. Yet, you insist that these coincidences are just a fluke. This is a point that you can't seem to comprehend or fail to acknowledge.

May I recommend you read The Blind Watchmaker? [img]/images/graemlins/smile.gif[/img]

I'll take a look.

may I recomend the case for a creator by Lee Strobel. I know at least one person on this forum doesn't think much of the author but that's not where the interesting content is. It gives good coverage of the main arguments for Intelligent Design through a series of interviews with the leaders in the field.

One example... Your talking about a flying rock, what if it were 1,000,000,000 rocks that hit 1,000,000,000 different houses in order and landed on the words that rewrote a shakespeare classic? Is it the same, well those 1,000,000,000 rocks had to land somewhere...
I think there has to be a limit to this kind of thinking, will no amount of coincidences that point towards a creator ever make you think "maybe it's not a mistake"??