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Your “Botched Body”: Bad Design or Bad Logic?

Over the past weekend, the Wall Street Journal published an essay, “The Botch of the Human Body,” by biologist Nathan Lents. The article previews the argument of a forthcoming book Dr. Lents has written about the absence of design in the human body. Although his thesis seems to be a bit broader, and to involve a fair bit of bald-faced assertion and imaginative story-telling, much of his argument falls into the “bad design” category.

As we all know by now, evolution doesn’t produce good designs except when it does. Or as Matti Leisola puts it in his recent book, Heretic, “[Evolution] produces exquisitely fine-tuned designs except when it produces junk. Evolution is random and without direction except when it moves toward a target.”

Evolution News readers will be interested to compare Dr. Lents’s view of the deeply flawed human body with Dr. Howard Glicksman’s compelling series, “The Designed Body.”

Dr. Lents is quick to find fault with various systems in the human body, and manages to ignore any contrary evidence, such as that discussed by Jonathan Wells in a post here last week on the mammalian eye that references Lents. Contrast this with Dr. Glicksman’s series, in which he argues to exactly the opposite effect. My engineering take on Dr. Glicksman’s series is here and here.

For me, coming from an engineer’s perspective, whenever a complex system of systems works at all, it seems counterproductive to attempt a “bad design” argument. Almost invariably, when such arguments are trotted out, it has less to do with actual bad design and more to do with one of the following causes:

Not understanding the design. This includes key design criteria, like the design objectives for the system, its functional requirements, all relevant design constraints, all relevant non-functional requirements (like redundancy, robustness, adaptability…), and any other system properties that the designer might have desired.

Without a proper understanding of the design, it’s awfully hard to claim the design doesn’t pass muster.

Not accounting for design tradeoffs. Some bad design examples are simply the natural consequences of good design decisions made elsewhere. All complex systems involve conflicting design requirements, so design tradeoffs must be weighed and carefully selected. As a result, decisions that are optimal for the whole may appear suboptimal with respect to a given subsystem or component. A good design to solve one engineering problem might easily exacerbate another engineering problem.

For example, the same blood pressure needed to force blood to flow uphill to the brain will tend to cause blood to pool in the feet (at least when we’re standing), so other subsystems are required to overcome these issues. Is this good design or bad design?

Engineers spend a good deal of their lives working with these issues. Biologists, perhaps a bit less.

Failure to acknowledge degradation over time. It should come as no surprise that all living systems, including the human body, degrade over time. Assembly errors can occur in development. Features essential for fetal development sometimes get in the way once the body matures. Diseases can degrade function. Knees that worked well in your twenties may complain when you reach your seventies. And there’s the potential for inheritable defects. Do any of these mean the body is not designed?

Logical fallacy. No rocket science is required to realize that “bad design” ≠ “no design.” Even if it could be proved that a body system or component was poorly or even terribly designed, this in itself would be insufficient to draw any conclusions about the participation or quality of any designer(s). And it’s hardly proof that random or gradual causes were able to generate a working, complex system.

Aesthetic considerations. In some cases a design may violate some sort of subjective aesthetic considerations, which some folks have trouble distinguishing from bad design. You can argue about the designer’s vision or taste, but this is not sufficient warrant to argue that the system wasn’t designed.

Appeals to bad design typically include smug statements like “What sense could it ever have made” (Lents, on the shape of the human spine) or “like a useless pile of rocks” (Lents, on the bones in the hand and foot) or “No tidy-minded engineer would do it that way” (Dawkins, on the mammalian eye). Such arguments invariably boil down to something like, “I wouldn’t have done it that way,” or “I just don’t like the way it works.”

It can be a lot of fun to ask those pushing these arguments how many actual working systems they have successfully designed and constructed. How many design tradeoffs did they make in doing so? How did they resolve conflicting design constraints, and what impacts did these decisions have on other (sub)systems? And to what extent did their successful designs compare in complexity to the human body?

In the end, then, the bad design argument almost always results in a bizarre blend of ignorance and arrogance that is apparent even to non-scientists.

And this at least suggests what I’ve long suspected — the explanatory sufficiency of neo-Darwinism is exhausted, with little substance left to offer in the face of the coherent complexities being discovered in living systems. As their position weakens, proponents seem to grasp at any available straw to make their case.

The bad design argument is inherently weak, and relatively easy to deflect when all the engineering objectives and constraints are considered. So in my conversations with evolutionists, I’ve found it helpful to ask “bad design” proponents whether, in their own heart of hearts, they personally find the bad design argument to be compelling.

To their credit, a surprising number will admit that they do not. If they don’t find these arguments compelling, perhaps neither should you.

Photo credit: KeithJJ, via Pixabay.