I apologize for the delay in getting to Part 2 of our look at the argument from design.
As mentioned in Part 1, many agree with David Hume that arguments from design based on analogies (e.g., a watch and an eye) are suspect since the two things compared are often also disanalogous in many ways. On the other hand, William Paley’s form of the argument can be construed as an argument to the best explanation: In light of the apparent design we see in nature, design – rather than chance and/or necessity – appears to be the better explanation.
Del Ratzsch presents the argument formally as follows:
(5) Some things in nature (or nature itself, the cosmos) are design-like (exhibit a cognition-resonating, intention-shaped character R)
(6) Design-like properties (R) are not producible by (unguided) natural means—i.e., any phenomenon exhibiting such Rs must be a product of intentional design.
(7) Some things in nature (or nature itself, the cosmos) are products of intentional design. And of course, the capacity for intentional design requires agency of some type.
Most contemporary proponents of the design argument follow this inference-to-the-best-explanation approach. For example, recent developments in cosmology have led to arguments from design based on the fine-tuning of the universe for the existence of life. Robin Collins, for instance, points out:
1. If the initial explosion of the big bang had differed in strength by as little as one part in 1060, the universe would have either quickly collapsed back on itself, or expanded too rapidly for stars to form. In either case, life would be impossible. (As John Jefferson Davis points out, an accuracy of one part in 1060 can be compared to firing a bullet at a one-inch target on the other side of the observable universe, twenty billion light years away, and hitting the target.)
3. Calculations by Brandon Carter show that if gravity had been stronger or weaker by one part in 1040, then life-sustaining stars like the sun could not exist. This would most likely make life impossible.
Biochemist Michael Behe and others have argued that certain features of biological life are so complex and intricately constructed that it is impossible that they could have been formed in steps over time, as Darwinian evolution requires. His famous example is the bacterial flagellum, which he describes as “irreducibly complex” in this sense.
A related argument is Alvin Plantinga’s evolutionary argument against naturalism. Given that naturalistic evolution is true, our brains have evolved to maximize our ability to survive rather than apprehend truth. Thus we have no reason, on naturalism, to trust the deliverances of our own rationality. On the other hand, if our cognitive equipment has been designed by God, we do have reason to have confidence in it. Some naturalists, such as Patricia Churchland, seem to essentially agree with Plantinga’s claim:
Boiled down to essentials, a nervous system enables the organism to succeed in the four F’s: feeding, fleeing, fighting, and reproducing. The principle chore of nervous systems is to get the body parts where they should be in order that the organism may survive. . . . . Improvements in sensorimotor control confer an evolutionary advantage: a fancier style of representing is advantageous so long as it is geared to the organism’s way of life and enhances the organism’s chances of survival [Churchland's emphasis]. Truth, whatever that is, definitely takes the hindmost.