The "Fine Tuning" Argument

The "fine tuning" argument is one of the most common creationist arguments. To briefly summarize, creationists argue that there is a vanishingly small probability of:

  1. The human race evolving to be precisely the way it is.
  2. The Earth having precisely the right characteristics to support human life.
  3. The universe having precisely the right characteristics to produce Earth.

At this point, you may wish to visit the Probability page, and pay particular attention to the poker examples. Remember that in poker, there are many, many possible winning hands. While the odds of certain high-value poker hands may be quite low, the odds of drawing (for example) a double are quite high. In fact, doubles constitute more than 40% of all possible poker combinations.

So how does that apply to evolution? If you look at the three arguments above, you will notice that they all contain the same assumption: that there is only one possible winning hand. What if there are many? What if we are looking for a double rather than a royal flush? The odds of a winning hand skyrocket in that case, don't they?

"But if the density of water were just a tiny bit different, life as we know it could not exist!" a creationist might object. Aye, and there's the rub: life as we know it. How are we to know that a very different kind of life could not arise? We cannot, and in the absence of any way to evaluate this, it is impossible to calculate its probability. In other words, to use a poker analogy, there is no way to know whether we're looking for a royal flush or a double. We don't even know how many cards there are in the deck, so not only can we not determine how many winning hands there are, we can't determine how many losing hands there are. This, then, is the first problem with the "fine tuning" argument:

In the absence of real data, the "fine tuning" argument simply assumes that there is only one winning combination, and an infinite number of losing combinations.

The creationist might answer as follows: "Even if there are many possible kinds of life, the fact remains that our world is very finely tuned to support our particular kind of life." This leads us to the second problem with the "fine tuning" argument:

The "fine tuning" argument assumes that the Earth is "fine-tuned" to support humans, rather than humans being "fine-tuned" to live on the Earth.

This is a preposterous assumption: since the Earth came before we did, it should be blatantly obvious that if one is optimized for the other, then we must be optimized to live on Earth, rather than the Earth being optimized to support us. This particular "fine tuning" argument was raised by creationists back in the 19th century, when scientists mocked it by asking whether the human nose was perfectly designed to hold up eyeglasses. Worse yet, we know that the Earth's environment was considerably different in past epochs, with major temperature variations and other differences such as much higher oxygen content in the atmosphere (thus favouring giant insects which would feast on us).

"All right," the creationist might answer, "but what about fine-tuning between species? For example, why is a banana so nutritious for human beings to eat?" This is where we run into the third problem with the "fine tuning" argument:

Despite considerable scientific literature on the mechanism of biological adaptation, the "fine tuning" argument assumes that adaptation is a completely random process.

How else can one interpret their argument that there is only a small probability of an organism being well-adapted to its environment? The mechanism of natural selection will ensure that animals which are not well-adapted to their environment will not survive or reproduce: a fact which made evident by the vast number of extinct species in the fossil record. It is not a matter of "probability"; there is a 100% probability that natural selection will occur, and in fact it occurs every day, all throughout the environment.

To even describe this as a problem of probability betrays an assumption that this whole process is random, hence no adaptation is possible without God's intervention. This in turn means that God must have "fine-tuned" every species himself, which leads us to the fourth problem with the "fine tuning" argument:

The "fine tuning" argument cannot explain the vast number of extinct species in the fossil record.

Remember that the "fine tuning" argument contains two premises:

  1. Everything in the ecosystem was "fine tuned" to work together by God.
  2. Natural selection cannot explain biological adaptation.

Given those two premises, how do proponents of the "fine tuning" argument explain all of the species which were obviously not well-adapted to their environment, and which therefore became extinct? Was God on his lunch break at the time? Natural selection explains them quite neatly, but according to the "fine tuning" argument, every single species on Earth was individually designed by God and "fine tuned" to work well with its environment! Therefore, all of these extinct species can only be interpreted by a "fine tuning" advocate as evidence of God's incompetence or negligence.

To summarize, there are four key problems with the "fine tuning" argument:

  1. Unfounded premise #1: it makes assumptions about the numbers of winning and losing combinations, with no reasoning whatsoever.
  2. Unfounded premise #2: despite the fact that the Earth came first and the environments of past epochs were highly unsuitable for modern humans, it assumes that the Earth was designed from the beginning to support human life, rather than humans being optimized to live on present-day Earth.
  3. Outright lie: it assumes that biological adaptation is a completely random process.
  4. Failed prediction: it predicts that there would be no such thing as a species which is not well-adapted to its environment (ie- the kind of species which dies horribly and goes extinct), because God intervenes in this process and "fine tunes" it himself. Therefore, its predictions are severely rebuked by the vast number of extinct species in the fossil record.

In short, you can't argue that God "fine tuned" the universe to support life, because you don't know how many other configurations are possible, or whether they would work to support some kind of life. You also can't argue that the Earth was "fine tuned" from the beginning to support humans because it came long before we did, and the ancient environment was actually rather unsuitable for humans. And finally, if God has been individually "fine tuning" every species on Earth, then he must have taken a lunch break for the past three billion years, because species have been going extinct by the millions over that time. That does not seem consistent with the idea that they were all being "fine-tuned" by an omniscient God. Perhaps his tuning fork was broken.

Last updated: August 29, 2007

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