The anthropic principle is a teleologic argument used most often to counter arguments for intelligent design. Those who believe in ID often argue that the multiple contingencies required for us to have come into existence are tenuous and improbable, therefore there must have been a design or plan. The anthropic principle counters that since we are here, any arguments of contingencies are irrelevant--we are already here, the probability of our existence is 100%, so the universe must be adequate for our existence, otherwise we should not be having such a dull argument.
The ID argument from contingencies is also an example of begging the question. We do not know if changing any physical constants in the universe would render life impossible. The anthropic argument counters this idea, but it has its flaws. As a teleologic argument, it takes a "it just is" approach, which could be argued is a "conversation-stopper", much in the way "Goddidit" is. However, the anthropic principle is at least true, in the sense that the universe is hospitable to us, our existence being the primary proof.
 Fine-tuned universe
The anthropic principle is often associated with the concept of the "fine-tuned universe" - the idea that if any one of several fundamental constants were slightly different then stars would not form and life would be impossible. This argument is sometimes used to support the idea that the universe was "designed" as it is claimed that this situation is so highly improbable that it must be deliberate.
However in August 2008 New Scientist ran an article "In the Multiverse Stars Burn Black"  in which it pointed out that the above assumption is simplistic. While it is true that changing one, and only one, universal constant may render life-supporting universes impossible - that is not the case if various constants are changed at the same time. When theoretical experiments were run on different potential universes with multiple variations in their constants, some 25% were found to be capable of forming stars.
 Counter Apologetics
The Anthropic Principle (TAP) is a straw man, weakened by the fact that it is basically a tautology. It can be eliminated altogether by the multiple universes, quantum mechanics and M-theory. TAP cannot be relied upon to prove that God exists.
A major criticism of the Anthropic Principle is that it is a tautology, or circular reasoning. In relation to the universe the tautology is that because we are here, we exist to ask the question. If we did not exist the question could not be asked. Or stated differently, if the features of the universe were incompatible with our existence, we would not be here to notice it.
 Begging the Question
The phrase 'fine-tuning' presupposes that the physical constants can be fine-tuned. It thus introduces a 'fine-tuner', God, as one of the premises of the argument. In another sense, it has not been proven that there actually is a way to change the physical constants, and as long as that is not done the argument is insubstantial. Thus the first argument against TAP is that it uses the unproven assumption that this fine-tuning is possible.
TAP assumes that only a very small number of possible universes would bring forth life. This statement is certainly true for the particular kind of carbon-based life that we know. Other forms of simpler life may exist, possibly helium-based life. Thus, TAP has not shown that our Universe is special in any way. If most Universes would bring forth life, the fact that ours has done so needs no explanation.
TAP claims that our Universe is special since it brought forth life, excluding other Universes since they are not special to bring forth any life. Even if life failed to come into existence, other things at least as interesting might happen. Once again, TAP has not proven its claim that our Universe is special.
 There may be only a few or no true anthropic numbers
Carr and Rees argued that although there appear to be a myriad number of so-called anthropic coincidences or constants, only four are especially critical. These are me (mass of the electron), mu (mass of the up-quark), md (mass of the down-quark), and g, the Grand unified coupling constant that determines the strength of the strong, electromagnetic, and weak forces. Taking this line of reasoning a step further, Kane and colleagues proposed that,
In string theories all the parameters of the theory——in particular all quark and lepton masses, and all coupling strength——are calculable, so there are no paramters left to allow anthropic argumeents...
According to Stephen Hawking, there is a 98 percent chance that a universe of a type as ours will come from the Big Bang.
 Copernican Principle
The Copernican Principle is the opposite of the Anthropic Principle and states that humans do not occupy a privileged place in the universe. Successive astronomical discoveries seem to support this principle. In the Middle Ages it was assumed that God created man in his image, and as such, man and the Earth were the center of the universe. Copernicus and Galileo abolished the illusion that the Earth was the center of the solar system and put the Sun in its rightful heliocentric place. Then the multiverse concept suggested that our universe may be just one of the many constantly sprouting new universes, further diminishing the Anthropic principle conclusion that the universe is here just for us. The Anthropic Principle emphasizes the rarity of life and consciousness while the Copernican Principle forces us to realize that it was not all done just so we could exist.
 Other reasons
Is the world fine tuned for life? Let us ignore all the lions, bears, tigers, and sharks that would eat us. Let us ignore all the bacteria and viruses that want to infect us. Let's ignore all the poisonous snakes, fish, plants and mushrooms that would kill us. Let's ignore the forest fires, blizzards, tornadoes, tsunamis, hurricanes, avalanches, earthquakes, landslides, and volcanoes that can also kill us. Let's ignore the fact that a fall from a height greater than 10 meters would probably kill us, or that submersion underwater for over 10 minutes is likely to be fatal.
Yes, let’s ignore all that and assume that the Earth is a perfect place to support life. Let's for a moment wrap ourselves in a blanket of ignorance and arrogance and assume that the Earth, and the universe, were designed clearly just for us. Unfortunately, most of the Earth is off-limits to human life. Take us above 8,000 meters above sea level and we will slowly die from depressurization and lack of oxygen. Going below 2,000 meters below sea level and we will slowly cook from the heat of the Earth’s interior. It turns out that less than one-half of 1 percent (0.46%) of the earth’s total volume is capable of sustaining human life—meaning that, even if we manage to imagine that the Earth is Eden, we know it is not. More than 99.54% of it would kill us rather quickly.
But this is just Earth; perhaps the solar system around us would be more suitable for us. Actually, the answer is no. Go outside of the Earth’s atmosphere and you would quickly die in the vacuum of space. And if the 0 pressure did not get you, the scorching heat in the Sun, the freezing cold in the shade, or the cosmic radiation would kill you quickly.
What about all those other planets? Well, you would burn or freeze on Mercury, freeze on Pluto, suffocate and then freeze on Mars. There is no place to stand on Saturn, Jupiter, Neptune or Uranus, and their moons are lethally cold. On Venus, you would be cooked and crushed to death in short order.
So, the rest of the solar system does not look too good for human life. But it gets worse. Let’s assume that every star in every galaxy has an Earth-like planet orbiting it. Even with these gross assumptions, less than 0.0000000000000000000000000000000000073% is habitable for human life. In other words, 99.9999999999999999999999999999999999927% of the universe is not habitable for life. Kind of takes the wind out of the sails for the fine-tuning argument.
If the universe was fine-tuned for us, surely a bit more of it would be habitable. The numbers are so absurd that it defies comprehension. It is equivalent to a person after exploring 1.6 BILLION rocks like our Moon and finding one single virus particle on only one of the moons and collectively saying they are fine-tuned for life. Or having six MILLION Olympic-sized swimming pools that can collectively hold no more than a single molecule of water, yet claiming they are fine-tuned for water storage. Or claiming that a hard drive the size of the earth that can only store one bit (1/0), or a hard drive the size of Jupiter cannot hold even hold a single tweet on twitter, is fine-tuned for storing data. Or claiming that 2 MILLION 50-ton cranes that can't collectively hold more than a single proton are fine-tuned for lifting. Or claiming that a plane at full speed travels less than one-tenth of 1 percent of the diameter of a proton over 10 billion years is fine-tuned for speed.
If you think these examples are ridiculous, then you would agree that so too is the argument that the universe is fine-tuned for life. It does not take a genius to realize how absurd and flawed this argument truly is. If this is the best it could possibly be, if this is the best environment using the natural laws of the universe that could allow human life, then it seems that the creator is not as all-powerful after all, or perhaps is not as well-disposed toward us as he is made out to be.
Let us also ponder the enormous waste of matter. The hundred billion galaxies, each with the order of a hundred billion stars, are composed mostly of “atomic matter”, that is, chemical elements. The portion that is luminous, that is, visible to the eye and optical telescopes, constitutes just one-half of one percent of all the mass in the universe. Another 3.5 percent of the matter in galaxies is of the same atomic nature, only non-luminous. Just 2 percent of atomic matter is composed of elements heavier than helium. One-half of 1 percent of this is composed of carbon, the main element of life. That is, 0.0007 of the mass of the universe is carbon. Yet we are supposed to think that God specially designed the universe so it would have the ability to manufacture, in stars, the carbon needed for life?
 Douglas Adams
“”. . . imagine a puddle waking up one morning and thinking, 'This is an interesting world I find myself in, an interesting hole I find myself in, fits me rather neatly, doesn't it? In fact it fits me staggeringly well, must have been made to have me in it!' This is such a powerful idea that as the sun rises in the sky and the air heats up and as, gradually, the puddle gets smaller and smaller, it's still frantically hanging on to the notion that everything's going to be alright, because this world was meant to have him in it, was built to have him in it; so the moment he disappears catches him rather by surprise. I think this may be something we need to be on the watch out for.
|—Speech at Digital Biota 2, Cambridge, UK, 1998, As quoted in Richard Dawkins' Eulogy for Douglas Adams|
- Observation selection effects, the anthropic principle, self-locating belief, and associated applications and paradoxes in science and philosophy Well worth a read, or a least a scan.
- Emil Karlsson. "Summary of Victor Stenger’s Case against the Fine-tuning Argument" Debunking Denialism, Defending science against the forces of irrationality (blog). November 18, 2011.
 See also
- Random chance
- Texas sharpshooter fallacy
- Essay:Why the "Fine-Tuned Universe" Argument is Bogus
- ↑ New Scientist - In the multiverse stars burn black
- ↑ Carr, B. J. & Rees, M. J. The Anthropic principle and the structure of the physical world. Nature. 278 605, 1979
- ↑ Kane, G. J., Perry, M. J. & Zytkow, A. N. The Beginning of the End of the Anthropic Principle. arXiv:astro-ph/0001197 2: 1-13, 2005
- ↑ Hawking, S. en.wikipedia.ord/wiki/Anthropic_principle. 2004