The Argument from Fine-Tuning
If you and I were each to independently write down a number between one and a thousand, to compare those numbers, and to find that they were identical, then this would stand in need of explanation. If we were to repeat this test ten times, each time finding that the numbers that we had written down were identical, then this would be strong evidence that what was happening was more than a mere coincidence.
This is because the theory that there is some connection between my number and your number explains the succession of agreements between our numbers in a way that the theory that there isn‘t doesn‘t. If there were some connection between the numbers that each of us is writing down, then we might expect our numbers to be the same. If there were no connection, then the succession of agreements would be vastly improbable. The succession of agreements therefore confirms the theory that there is some causal connection between our respective selections of our numbers.
The argument from fine-tuning, a form of teleological argument for the existence of God, is the argument that the state of the universe, like the succession of agreements in our numbers, stands in need of explanation. The state of the universe, the argument suggests, confirms the theory that the universe was created by an intelligent being for the purpose of supporting life, just as the succession of agreements between our numbers in the example above confirms the theory that there is some cause of their agreement.
What is it about the universe, then, that requires explanation? The argument from fine-tuning suggests that the fitness of the universe for life either involves a series of staggering coincidences, or is the result of intelligent design.
There are many ways that the universe might have been; the overwhelming majority of these would not have been such as to support the development of life. The expansion of matter after the Big Bang, for instance, had to occur at the right rateâ€”fast enough to avoid a Big Crunch but slow enough to allow for the formation of planetsâ€”in order for life to arise; it did. The strengths of the physical constants (e.g. the strong force and the weak force) had to fall within certain bounds in order for life to arise; they do. The greater the number of conditions necessary for life, the less likely it is that the universe satisfies these conditions by chance. The argument from fine-tuning has now been developed to include a vast number of such conditions.
For more on the modern approach to the argument from design see William Dembski’s articles on the subject.
Objections to the Argument from Fine-Tuning
It is common to think that the argument from design is obsolete, that since Darwin’s theory of evolution there has been no need to invoke God to explain the appearance of design in nature. According to this evolutionary critique, the universe was not designed to fit us; rather, we evolved to fit the universe.
Another objection to the argument from fine-tuning is that all possible universes are improbable, and that the existence of some improbable universe was therefore inevitable. Just as all possible combinations of lottery numbers is unlikely, but the drawing of a particular set does not imply cheating, so all possible universes are unlikely, but the existence of any particular one of them is unremarkable.
A further criticism of the argument appeals to the weak anthropic principle. This objection notes that it would be impossible to observe the universe to be unable to support life, because if the universe were unable to support life then there would be no one to observe it. There is, the criticism concludes, therefore no need to explain the fact that we observe the universe to be fit for life.
A final objection to the argument uses the many worlds hypothesis to evade its conclusion. Our universe, according to this hypothesis, is just one of many; there may even be an infinite number of universes; perhaps every possible universe exists. If any of these claims is correct, then that vastly reduces the need to explain the existence of a universe capable of supporting life.