A full discussion of these arguments can be found in Craig's article here. What follows is the introductory paragraph from that article.
4. The Teleological Argument from Fine-tuning
We now come to the teleological argument, or the argument for design. Although advocates of the so-called Intelligent Design movement have continued the tradition of focusing on examples of design in biological systems, the cutting edge of the contemporary discussion concerns the remarkable fine-tuning of the cosmos for life.
Before we discuss this argument, it’s important to understand that by “fine-tuning” one does not mean “designed” (otherwise the argument would be obviously circular). Rather during the last forty years or so, scientists have discovered that the existence of intelligent life depends upon a complex and delicate balance of initial conditions given in the Big Bang itself. This is known as the fine-tuning of the universe.
This fine-tuning is of two sorts. First, when the laws of nature are expressed as mathematical equations, you find appearing in them certain constants, like the constant that represents the force of gravity. These constants are not determined by the laws of nature. The laws of nature are consistent with a wide range of values for these constants. Second, in addition to these constants, there are certain arbitrary quantities that are put in just as initial conditions on which the laws of nature operate, for example, the amount of entropy or the balance between matter and anti-matter in the universe. Now all of these constants and quantities fall into an extraordinarily narrow range of life-permitting values. Were these constants or quantities to be altered by less than a hair’s breadth, the life-permitting balance would be destroyed, and no living organisms of any kind could exist.
For example, a change in the strength of the atomic weak force by only one part in 10100 would have prevented a life-permitting universe. The cosmological constant which drives the inflation of the universe and is responsible for the recently discovered acceleration of the universe’s expansion is inexplicably fine-tuned to around one part in 10120. Roger Penrose of Oxford University has calculated that the odds of the Big Bang’s low entropy condition existing by chance are on the order of one out of 1010(123). Penrose comments, “I cannot even recall seeing anything else in physics whose accuracy is known to approach, even remotely, a figure like one part in 1010(123).”
So when scientists say that the universe is fine-tuned for life, they don’t mean “designed”; rather they mean that small deviations from the actual values of the fundamental constants and quantities of nature would render the universe life-prohibiting or, alternatively, that the range of life-permitting values is incomprehensibly narrow in comparison with the range of assumable values. Dawkins himself, citing the work of the Astronomer Royal Sir Martin Rees, acknowledges that the universe does exhibit this extraordinary fine-tuning. And it’s not just each constant or quantity that must be exquisitely finely-tuned; their ratios to one another must be also finely-tuned. So improbability is multiplied by improbability by improbability until our minds are reeling in incomprehensible numbers.
Here, then, is a simple formulation of a teleological argument based on fine-tuning:
1. The fine-tuning of the universe is due to either physical necessity, chance, or design.
2. It is not due to physical necessity or chance.
3. Therefore, it is due to design.