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The Anthropic Cosmological Principle

A review by Gert Korthof
updated 6 Aug 2001 (first published: 4 Jun 1998)

The Anthropic Cosmological Principle

John D. Barrow, Frank J. Tipler (1986)
The Anthropic Cosmological Principle
   The Anthropic Cosmological Principle is the most impressive book I read the last decade. If this book does anything: it places life on earth in its cosmological context. Life and the universe will never be the same after this book!

    It is well known that there would be no life without the sun and that the rotation of the earth causes day and night and the seasons. These influences have an undeniable effect on life on earth. But this is all trivial compared with what John Barrow and Frank Tipler have to offer in this book. Slowly one begins to realise, working one's way through the chapters, that the existence of the sun, the earth, but also the chemical elements are the outcome of a process, just as the existence of life and the diversity of life forms is the outcome of a process.
   Since Copernicus we are no longer the centre of the universe. And our planet is so small compared to the vastness of the universe. However, we should not be surprised to observe that the universe is so large. No astronomer could exist in one that was significantly smaller. The universe needs to be as big as it is in order to evolve just a single carbon-based life-form. The universe also needs to be as old (15 billion years) as it is to evolve carbon-based life. This is because carbon is produced in stars, and this process takes over 10 billion years. The whole universe is so big and so old for us? Designed for us? The Anthropic Cosmological Principle is an invaluable source of information for atheists and theists alike. There are difficult sections with a lot of mathematics, but these can be skipped without problem.
Fine tuning    Most interesting I found the summing up of 'life-supporting' (life enabling) properties of the cosmos:
  • the production of a mixture of Hydrogen and Helium after the Big Bang
  • long living hydrogen burning stars
  • the production of the elements C, O, N, S in a star
  • the distance of a planet (earth) to the star (sun): not too far, not too close
  • the minimum size of the planet (to hold an atmosphere)
  • atomic and molecular stability
  • the unique properties of such a simple molecule as water
and much, much more.
I wished that the astronomy, chemistry and biology lessons in my education had been integrated in the way Barrow and Tipler do it in their book. It shows close connections between seemingly unrelated facts such as the production of Carbon in the interior of the sun; the very useful chemical properties of Carbon and the fact that all life on Earth is based on Carbon. Usually biology textbooks ignore these connections. A good example of a modern evolution textbook where biology is placed in its cosmological context is Monroe Strickberger (5). The architects of the neo-Darwinian synthesis tried to unify biology by integrating all separate biological disciplines into one biological science. What Barrow and Tipler have done is extending this synthesis to include both biology and cosmology, and relevant parts of physics and chemistry.
    Whether or not one claims that fine tuning is extremely precise and cannot be a coincidence, and whether or not one gives a theistic or atheistic interpretation of the facts, the lasting contribution to science of Barrow and Tipler is that they show that the building blocks of life are not produced on Earth but in the cosmos. So we cannot understand life without understanding the building blocks of life (7). And those building blocks cannot be understood without knowing the processes that produced those building blocks. And these facts are true independent of the Anthropic Cosmological Principle itself.

Evolution-Creation controversy.

   Ever since reading this book, I was amazed that Intelligent Design Creationists like Phillip Johnson, Michael Denton(1986), Michael Behe and William Dembski, who focus their attacks on biological evolution, hardly exploited the 'fine-tuning' argument to prove the existence of a designer. It is so obvious, that I fail to see why they don't use the argument. Maybe those creationists don't like that evolution is taken for granted by Barrow and Tipler. Or maybe they are just too convinced of the association of evolution and atheism, to see that a universe with evolution could be designed. If fine tuning is preparation, if fine tuning is about initial conditions, then evolution is inescapably associated with fine tuning. Maybe the 'preparation' of the cosmos for life on Earth did take a little bit too long? Just as the 'preparation' of the Earth for humans did take a little bit too long? If the ultimate goal of the preparations was to create humans, then the processes assigned to the job didn't seem to be very efficient. Indeed there is a contrast between 'intelligent fine tuning', and the subsequent inefficient processes. Maybe that's the reason why Young Earth Creationists ('one week is enough') decided that the Earth and the cosmos are young, thereby eliminating the long preparation time and making creation more efficient (but why one earthly week?).
    It would be very difficult for creationists who committed themselves in public and in print to the incompatibility of Darwinistic evolution and theism, to abandon that view in favour of the 'fine tuning' argument. Michael Denton is the only writer I know of who did exactly this (3). Theists who do accept fine tuning, like Swinburne (1), as far as I know never had a problem with biological evolution. To make the matter even more complicated: the theists Hugh Ross (2) and Dean Overman (6) believe that both fine tuning and the creation of life is done by God. Whenever the Anthropic Principle is used to explain away fine tuning, one can expect theists to object (4).
    On the other hand it is good to notice that Barrow and Tipler, considering their interest in designed features of the universe, do not think for a moment that the origin of life and the origin of humans needed (divine) intervention. One cannot find a trace of doubt in their book that life evolved. (As if it were enough to fine tune the initial conditions of the universe and all the rest would follow ...). A good illustration of the confidence in evolution is the 'Biological Constraints on the age of the earth' (page 159). They call it the first successful use of an anthropic argument. Their argument runs like this:
As the time to evolve humans was at least 1 billion years, and since solar energy was necessary all the time for life, the sun must have been stable for at least 1 billion years. This again restricts possible sizes and the composition of the sun. So biological evolution restricts cosmology. This shows that the authors take evolution as a fact, as known background knowledge. Maybe they are so used to an evolving universe, the birth and death of stars, (etc.) that biological evolution seems only natural. Let the biologists find out the details about evolution.
    I think there are problems with the claim that the universe has been designed for humans. For example the probability that humans evolved, is very low. So: fine tuning is fine, but as long as evolution depends on a directionless random process, the fine tuning only creates the necessary conditions, but does not give a guarantee that humans and even life itself would occur.

Do Barrow and Tipler believe in Design?

   Clearly they are not Young-Earth-Creationists! But they are deeply interested in design (95 pages on the history of design arguments) and purpose in biology (another 95 pages). They do see themselves in the age old tradition of design arguments. They are interested in everything that has been rejected by mainstream science (Teilhard de Chardin, etc.). I found it extremely difficult to pin them down. Let us have a closer look at the Anthropic Principle in operation when applied to a familiar anti-Darwinist argument: the improbability argument of the origin of genes en proteins. The following quote was found in the footnotes :
"Salisbury argued that the enormous improbability of a given gene, which we computed in the text, means that a gene is too unique to come into being by natural selection acting on chance mutations. WAP self-selection refutes this argument, as Doolittle in Scientists confront creationism, ... has also pointed out. " (p575). [WAP=Weak Anthropic Principle]. (bold is mine).
So WAP refutes any argument against evolution and even Darwinism, because WE ARE THERE ! And this conclusion is delegated to the footnotes. So: no matter how improbable the evolution of life and humans and no matter how many unresolved problems in neo-Darwinism, WE ARE THERE ! So there must be something wrong with the calculation in question. So any argument telling us we could not have evolved, simply and clearly must be wrong. It is obvious that the authors implicitly reject any (divine) intervention in natural processes. And everyone who accepts that science works exclusively with natural causes, must come to the same conclusion. WAP can eliminate theories and calculations that 'deny' our existence, but has nothing to say about which theory explaining our existence, is right.
    It is a mystery why Barrow and Tipler are so deeply interested in design. Maybe they do not have a problem with the initial conditions of the universe being 'designed', as long as everything after that is not disturbed by 'interventions'. -

book "The Anthropic Cosmological Principle."
by John D. Barrow & Frank J. Tipler
Oxford University Press.
paperback reprint 1994
706 pages

  1. Introduction ...1
  2. Design Arguments ...27
  3. Modern Teleology and the Anthropic Principles ...123
  4. The Rediscovery of the Anthropic Principle ...219
  5. The Weak Anthropic Principle in Physics and Astrophysics ...288
  6. The Anthropic Principles in Classical Cosmology ...367
  7. Quantum Mechanics and the Anthropic Principle ...458
  8. The Anthropic Principle and Biochemistry ...510
  9. The Space-travel Argument against the Existence of Extraterrestrial Intelligent Life ...576
  10. The Future of the Universe ...613
  11. Index ...683-706
each chapter closes with References


  1. See my review on this site of Richard Swinburne's Is there a God?.
  2. A good online summary of the constants of physics and the parameters of the planet earth is given in Design and the Anthropic Principle by Hugh Ross. At the same time the article is a good illustration of a theist who accepts both the fine tuning argument and the impossibility of spontaneous origin of life as design proofs. [if life had to be specially created, there must be something wrong with the fine tuning?]
  3. Michael Denton(1998) Nature's Destiny. How The Laws of Biology Reveal Purpose In The Universe. See review on this site.
  4. For example the theist William Lane Craig in: "Barrow and Tipler on the Anthropic Principle vs. Divine Design". Craig perceives the Anthropic Principle as anti-theistic. He criticises Barrow & Tipler's claim that we should not be surprised to observe a fine tuned universe and so don't need an explanation for the fine tuning. We should be surprised and we do need an explanation according to Craig. The need for an explanation is not explained away by the Anthropic Principle. Of course Craig gives a theistic explanation.
  5. Monroe Strickberger(2000) Evolution. Third Edition. (review on this site)
  6. See review on this site. Note the conflict between fine-tuning and anti-evolution.
  7. Proponents of 'Artificial Life' (life created in the computer) claim they don't need Carbon to create life. Of course not! However life on Earth is definitely Carbon-based!

Further Reading:

  • A critical discussion of the fine tuning argument is: "Intelligent Design. Humans, Cockroaches, and the Laws of Physics" by Victor J. Stenger, professor of physics and astronomy at the University of Hawaii. Recently (2003) he published Has Science Found God? The latest Results in the Search for Purpose in the Universe, in which he discusses the origin of the universe and fine tuning of physcial constants.
  • "Out in the cold", New Scientist 10 June 2000, pp33-35 discusses the criticism of cosmologist Paul Steinhardt, who claims that the anthropic principle is sloppy and unscientific, and why.
  • William Lane Craig: "Barrow and Tipler on the Anthropic Principle vs. Divine Design", a theistic interpretation.
  • Anthropic Reasoning and the Contemporary Design Argument in Astrophysics: A Reply to Robert Klee by Mark A. Walker and Milan M. Ćirković. (undated, visited on 19 Feb 2004) An interesting read.
  • Lynn Rotschild and Adrian Lister (ed) (2003) Evolution on Planet Earth. The impact of the physical environment, (publishers information). A fascinating review of all physical influences on the evolution of life on earth by specialists in different fields. The earth's atmosphere (oxygen and carbon dioxide levels), solar radiation, panspermia, gravity, temperature, continental drift, climate and extraterrestrial conditions for life. We will never have a complete theory of evolution and full understanding of evolution without the physical factors! Many illustrations. Textbook-like layout.
  • Nick Bostrom (2002) Anthropic Bias: Observation Selections Effects in Science and Philosophy (Studies in Philosophy) for anyone interested in fine tuning, anthropic coincidences and observation selection effects. It offers new conceptual and methodological tools for thinking about the large-scale structure of the world and the place of observers within it.
  • Victor J. Stenger (2004) Is the Universe Fine-Tuned for Us? in: Matt Young and Taner Edis (2004) Why Intelligent Design Fails: A Scientific Critique of the New Creationism contains a critique of the anthropic principle. [ 10 Jul 2005 ]
  • A Universe Right For You --- A book by J.M.Cohen 2006. This is a history of our universe, told from an anthropic perspective. [ 3 Feb 2006 ]
  • Geoff Brumfiel (2006) Outrageous fortune News feature NATURE|Vol 439|5 January 2006. Very useful and clearly written article about anthropic principle and the relation with string theory. With quotes from David Gross and Leonard Susskind. [ 3 Feb 2006 ]
  • A popular mainstream introduction into Astrobiology is: Astrobiology : A Brief Introduction by Kevin W. Plaxco & Michael Gross (2006). This is essential scientific background knowledge for those interested in 'fine-tuning' of the universe for life and the origin of life itself. Chapters: What is life? Origins of a habitable universe and planet, Primordial soup, Origin of life, Origin of cells, Evolution of life on earth, Life in extreme environments, Search for extraterrestrial life. [ 4 Jul 2006 ]
  • Fred Spier (2011) Big History and the Future of Humanity, Wiley-Blackwell, paperback. Big History is the approach to history in which the human past is placed within the framework of cosmic history, from the beginning of the universe up until life on Earth today.
  • John Barrow, Simon Conway Morris, Stephen Freeland, Charles Harper (editors) (2008) Fitness of the Cosmos for Life: Biochemistry and Fine-Tuning, Cambridge Astrobiology. 501 pp. (see: introduction page for details).


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Copyright © 1998 G.Korthof. First published: 4 Jun 1998 Last update: 6 Aug 2001. Further Reading: 12 Jun 2014