Free God: The Failed Hypothesis by Victor Stenger

of the attributes of God is that he designed the universe with at least one of his purposes being the existence of the complex structures we identify as life, with a special role for human life, then the failure to observe such design provides us with empirical grounds for concluding that a God with this attribute does not exist.
    Some authors use the term “design” to refer to any structure of atoms and molecules that exhibits some pattern or purpose.
    Indeed, many are inconsistent in their usage and definition of the term “design 47 .” In order to avoid any confusion on this matter, we will use
design
to refer to the act of an agent, be she divine or human, stupid or intelligent, to draw a blueprint—so to speak—of some artifact that is later assembled from that plan.
    The assembly process in some cases might require high intelligence, as the Wright brothers demonstrated at every step when they built a flying machine in their bicycle shop. Or, the assembly can be relatively mindless, as on a modern automated production line—unless you want to argue that the computers running the process are pretty smart themselves. Indeed, many use the methods of “artificial intelligence.” In any case, the assembly is unimportant unless the claim is being made that the assembly itself is a miracle. Since that is not normally an issue, what matters is the initial plan—a purpose that is either built into the contrivance from the beginning or not. In the example of the spiral discussed above, the broken symmetry of the spiral was not introduced by the programmer, me, on purpose.
    Now, we must be careful not to confuse a preexisting purpose with mere utility or function. A stone can be used to break a window; however, the stone was not designed for that purpose. A salt crystal has a structure. But that structure was not contrived so that food would taste better when sprinkled with salt.
    Similarly, all living organisms have many parts serving functions that are crucial for the survival of the organism. The question is: did an intelligent agent design that part for its present purpose, or did that function evolve by a combination of accident and the mechanisms of natural selection? In examining evidence for or against design in the world, we should look at whether the system being studied shows any sign of preexisting purpose or plan, or whether it can be seen to have evolved mindlessly by natural selection in response to the needs of survival or other purely physical mechanisms such as self-organization.
    Bad Design
    As mentioned, Paley drew an analogy between different parts of the human body and an exquisitely designed watch. In such a watch, every part—the balance, escape wheel, jewel, mainspring, and the rest—is carefully constructed to serve its specific functions as efficiently as possible. The parts can always be improved upon, but not by much if the original work was by an expert craftsperson. Watches and all the many devices of human design have very few wasted parts.
    Some evolutionists have tried to counter the Paley claim with what might be called the
argument from bad design,
pointing out all the ways that a competent engineer could improve upon what nature has given us.
    The parts of the human body hardly resemble a watch. In an article in
Scientific American
titled “If Humans Were Built to Last,” S. Jay Olshansky, Bruce Carnes, and Robert N. Butler have looked at flaws in the human body and shown how an engineer might have fixed them to enable us to live a hundred years or more in better health 48 . They trace our physical defects to the Rube Goldberg way evolution cobbles together new features by tinkering with existing ones. Natural selection does not seek out perfection or endless good health. The body has to live only long enough to reproduce and raise young. Species survival does not require that individuals survive long after reproducing. We humans do, albeit with decreasing vitality, because human