“If an intelligent (and benevolent) agent designed life, then studies of putatively bad designs in life-such as the vertebrate retina and virulent bacteria-should reveal either (a) reasons for the designs that show a hidden functional logic or (b) evidence of decay of originally good designs.”
This prediction deals with the issue of “bad design.” The ID concept has spawned many discussions on both sides of how an intelligent designer might or might not carry out a design. As mentioned repeatedly in these posts and comments, I believe that ID is non-scientific precisely because the proposed intelligent agent is not amenable to independent scientific observation to understand how it can effect a design. These discussions are therefore, in my opinion, quite worthless except to generate speculative arguments. What constitutes a truly bad design? How does one define bad design? How do we know what an indeterminate intelligent agent would or would not do? We simply don’t know.
Meyer speculates that such an agent would never do a truly bad design. Therefore there must be a reason for everything. Hence, what we think is bad, will be found to have some secret beneficial function. He hedges his bets and admits that perhaps a bad design could occur if a design point were originally good but decayed to a bad state. Why an intelligent agent wouldn’t be able or willing to prevent or avoid that is not at all clear.
In any case, I find this path to be a fruitless direction. Nothing will be gained by discussing what kinds of designs are good or bad with respect to an intelligent designer that we cannot study.