On the probability of evolution

 In the following post, I won’t try to calculate specific values but rather to explicate my own Knowledge-dependent frequentist probabilities by using particular examples.


I strongly encourage every reader new to this topic to first read my groundwork (Click here).

The great evolutionary biologist Stephen Jay Gould was famous for his view that Evolution follows utterly unpredictable paths so that the emergence of any species can be viewed as a “cosmic accident”.



Stephen Jay Gould

He wrote:

We are glorious accidents of an unpredictable process with no drive to complexity, not the expected results of evolutionary principles that yearn to produce a creature capable of understanding the mode of its own necessary construction.
“We are here because one odd group of fishes had a peculiar fin anatomy that could transform into legs for terrestrial creatures; because the earth never froze entirely during an ice age; because a small and tenuous species, arising in Africa a quarter of a million years ago, has managed, so far, to survive by hook and by crook. We may yearn for a ‘higher answer’– but none exists”

“Homo sapiens [are] a tiny twig on an improbable branch of a contingent limb on a fortunate tree.”


Dr. Stephen Jay Gould, the late Harvard paleontologist, crystallized the question in his book ”Wonderful Life.” What would happen, he asked, if the tape of the history of life were rewound and replayed? For many, including Dr. Gould, the answer was clear. He wrote that ”any replay of the tape would lead evolution down a pathway radically different from the road actually taken.”


You’re welcome to complement my list by adding other quotations. 🙂


Evolution of man


So, according to Stephen Jay Gould, the probability that human life would have evolved on our planet was extremely low, because countless other outcomes would have been possible as well.

Here, I’m interested to know what this probability p(Homo) means ontologically.

Bayesian interpretation

Image Of Thomas Bayes



For a Bayesian, p(Homo) means the degree of belief we should have that a young planet having exactly the same features as ours back then would harbor a complex evolution leading to our species.

Many Bayesians like to model their degrees of belief in terms of betting amount, but in that situation this seems rather awkward since none of them would still be alive when the outcome of the wager will be known.


Traditional frequentism


Let us consider (for the sake of the argument) an infinite space which also necessarily contain an infinite number of planets perfectly identical to our earth (according to the law of the large numbers.)

According to traditional frequentism, the probability p(Homo) that a planet identical to our world would produce mankind is given as the ratio of primitive earths having brought about humans divided by the total number of planets identical to ours for a large enough (actually endless) number of samples:

p(Homo)   ≈           f(Homo) = N(Homo) / N(Primitive_Earths).


Knowledge-dependent frequentism


According to my own version of frequentism, the planets considered in the definition of probability do not have to be identical to our earth but to ALL PAST characteristics of our earth we’re aware of.

Let PrimiEarths  be the name of such a planet back then.

The probability of the evolution of human life would be defined as the limit  p'(Homo) of

f'(Homo) = N'(Homo) / N(PrimiEarths‘)

whereby N(PrimiEarths‘)  are all primitive planets in our hypothetical endless universe encompassing all features we are aware of on our own planet back then and N'(Homo) is the number of such planets where human beings evolved.

It is my contention that if this quantity exists (that is the ratio converges to a fixed value whereas the size of the sample is enlarged), all Bayesians would adopt p'(Homo)  as their own degree of belief.


But what if there were no such convergence?  In other words, while one would consider more and more  N(PrimiEarths‘) f'(Homo) would keep fluctuating between 0 and 1 without zooming in to a fixed value.

If that is the case, this means that the phenomenon  “Human life evolving on a planet gathering the features we know” is completely unpredictable and cannot therefore be associated to a Bayesian degree of belief either, which would mean nothing more than a purely subjective psychological state.


Evolution of bird

I want to further illustrate the viability of my probabilistic ontology by considering another evolutionary event, namely the appearance of the first birds.

Let us define D as : “Dinosaurs were the forefathers of all modern birds”, a view which has apparently become mainstream over the last decades.

For a Bayesian, p(D) is the degree of belief about this event every rational agent ought to have.

Since this is an unique event of the past, many Bayesians keep arguing that it can’t be grasped by frequentism and can only be studied if one adopts a Bayesian epistemology.


It is my contention this can be avoided by resorting to my Knowledge-Dependent Frequentism (KDF).

Let us define N(Earths’) the number of planets encompassing all features we are aware of on our modern earth (including, of course, the countless birds crowding out the sky, and the numerous fossils found under the ground).

Let us define N(Dino’) as the number of these planets where all birds originated from dinosaurs.

According to my frequentism, f(D) = N(Dino’) / N(Earths’), and p(D) is the limit of f(D) as the sample is increasingly enlarged.

If p(D) is strong, this means that on most earth-like planets containing birds, the ancestors of birds were gruesome reptilians.

But if p(D) is weak (such as 0.05), it means than among the birds of 100 planets having exactly the known features of our earth, only 5 would descend from the grand dragons of Jurassic Park.


Again, what would occur if p(D) didn’t exist because f(d) doesn’t converge as the sample is increased?

This would mean that given our current knowledge,  bird evolution is an entirely unpredictable phenomenon for which there can be no objective degree of belief every rational agent ought to satisfy.



A physical probability dependent on one’s knowledge


In my whole post, my goal was to argue for an alternative view of probability which can combine both strengths  of traditional Frequentism and Bayesianism.

Like Frequentism, it is a physical or objective view of probability which isn’t defined in terms of the psychological or neurological state of the agent.

But like Bayesianism, it takes into account the fact that the knowledge of a real agent is always limited and include it into the definition of the probability.


To my mind, Knowledge-Dependent Frequentism (KDF) seems promising in that it allows one to handle the probabilities of single events while upholding a solid connection to the objectivity of the real world.


In future posts I’ll start out applying this concept to the probabilistic investigations of historical problems, as Dr. Richard Carrier is currently doing.



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Renewing the Evangelical mind: an interview with Peter Enns

Renewing the Evangelical mind: an interview with Peter Enns


In what follows, I had the immense privilege to interview Peter Enns (links), who is undoubtedly the leading progressive Evangelical theologian in the whole world.

Here are the topics we touched upon, albeit not necessarily in a chronological order.


1) Where Peter Enns comes from and how his thoughts evolved with time

2) How is evolution currently perceived among American Evangelicals?

a) Young Earth Creationism

b) Old Earth Creationism and Concordism

c) His own approach

3) What were likely the intentions of the original authors as they wrote the text?

4) One of the very foundation of Evangelicalism is the idea that God cursed us with a sinful nature, making misdeeds deserving an eternal punishment inevitable.
Can we find this concept in the very text of Genesis?

5) If Paul thought it was the case but the authors of Genesis 2 and 3 didn’t hold this view, what should we believe as modern Christians?

6) What is inerrancy and why is it viewed as the very foundation of Christianity by so many people?

7) What about God inerrantly gathering errant texts for His own purposes, as Professor Randal Rauser thinks it’s the case?

8) Many people say that if there is only a small mistake in one obscure book of the Old Testament, we can no longer trust the resurrection. What’s Peter’s response to this?

9) Problem of divine hideness:

Why would God not have given us an inerrant text rather than leaving us stabbing in the dark?

Why did He allow so many people to mistakenly assume its inerrancy?

10) What did God REALLY do during the history of Israel? Did He reveal Himself to a real Abraham and a real Mose?

11) Given the results of modern critical scholarship, what makes the Protestant Canon so special?
What does it mean to say that the imprecatory psalms were more inspired than books of C.S. Lewis on pain and love, and writings of Martin Luther King on non-violence?

12) Currently, there is a massive exodus from young people out of Conservative Christianity?
What are the causes of this?




For those interested by our conversation, I recommend the following resources:


Peter’s blog containing many insightful posts and Peter’s website full of great academic writings.

The following books are also worth looking:

The Evolution of Adam : What the Bible Does and Doesn’t Say about Human Origins.
Three Views on the New Testament Use of the Old Testament (Counterpoints: Bible and Theology).
Inspiration and Incarnation: Evangelicals and the Problem of the Old Testament.
Telling God’s Story: A Parents’ Guide to Teaching the Bible (Telling God’s Story).
Ecclesiastes (Two Horizons Old Testament Commentary).

UPCOMING: The Bible Tells Me So: Why Defending Scripture Has Made Us Unable to Read It.


Young earth creationism and the demise of Christianity

I have a confession to all of my readers.

I am a sadomasochist, I like to inflict pain on myself.

Consequently, I watched one of the latest video of Ken Ham about the “seduction of our kids”.


If I were to refute all fallacies in this single video, a whole library could not contain all books which would have to be written.

The Leitmotiv of Ken Ham’s was that “Secularists are here to capture your kids”.

He pointed out that 2/3 of all American college students lose their faith in God and showed us videos of deconversion where people have become atheists after having been confronted with the scientific evidence for evolution.

Ken Ham believes this is increasingly happening because there is not enough young earth creationism.

Tragically, quite the contrary is true. These young folks have given up their faith BECAUSE they have been indoctrinated by creationists who taught them that they ought to reject Evolution if they want to be Christians.

Now, I have two questions for my readers:

1) what is your favorite fallacy of Ken Ham?

2) do you believe that (as a species) young-earth creationism will die out and be competed out of existence?Importa

nt themes

Creation or Evolution?


George Murphy did a nice job showing that this is a false dichotomy and that we have good theological grounds for thinking that God used the nature He created for bringing about living things.

I would add that God can also act without breaking the laws of physics thanks to quantum randomness coupled with chaos theory.

And I will also say something very blasphemous: I am not sure that genetic Darwinism (natural selection acting on the genes) is the true story.

I believe that factors such as genetic drift, self-organization, strong emergence as well as cultural evolution (for higher animals) might very well turn out to have plaid a much more important role than what is currently thought.

I think that for many people, the main issue posed by evolution is the problem of evil: why did God allow nature to create all lifeforms if it goes hand in hand with such an intense pain?

While I believe it is challenging for every Christian, I fail to see why accepting an evolutionary account creates greater difficulties than those spawned by the alternatives.

Old earth creationists believe that God miraculously intervened in order to introduce every new species over million of years and that he let countless lifeforms die out through competition or natural catastrophes. This clearly does nothing to alleviate the problems of evolutionary pain.

Young earth creationists think that God cursed the whole universe just because two persons ate the wrong fruit. To my mind this is morally far worse than the two first options.

Link: http://www.asa3.org/ASA/PSCF/2001/PSCF3-01Murphy.html


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