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Is There a Michelangelo Building Sandstone Arches?

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Michelangelo reportedly taught novices how to carve a statue of David: you start with a block of marble, and chip away everything that doesn’t look like David. Easier said than done!

Now the Renaissance sculptor’s name has turned up in an unexpected place: a science article for BBC News about sandstone arches. The article reports on a new study in Nature Geoscience that explains how these beautiful, symmetric monuments are formed. Under a stunning photo of Rainbow Bridge, Jonathan Webb writes:

The study’s first author, Dr Jiri Bruthans from Charles University in Prague, said the new study revealed the "Michelangelo" behind some of the world’s most famous rocky landmarks.

"The stress field is the master sculptor — it tells the weather where to pick," he told BBC News.

This is metaphor, of course; we all know that neither Michelangelo nor any other intelligent designer built Rainbow Bridge, or Delicate Arch as featured in Science Magazine‘s short write-up. Still, we can use it as a case study in design detection.

Show photos of St. Louis’s Gateway Arch next to Delicate Arch, and even most fourth graders will likely be able to tell which was designed and which is natural. It’s almost intuitively obvious. But how do we know the difference? What do we mean by natural?

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The question becomes more philosophically interesting when you think about the nature of natural law. Do natural laws "make" things happen, or do they simply describe what usually happens? Many scientific realists prefer the former (as in "186,000 miles per second: it’s not just a good idea, it’s the law"). Strict empiricists, on the other hand, feel that only the latter can be justified: a natural law merely describes patterns in experience with no sense of obligation. In the extreme, one could not even be sure that the "law" will hold in the next instance.

Bruthans told the BBC that the "stress field…tells the weather where to pick." Sand grains under gravity tend to become compact, and therefore, stronger. As a result, the pillars of a natural arch will tend to be the strongest, and most resistant to erosion. They "tell" the weather where to pick only by resisting erosion, making it easier for other parts (like bumps sticking out) to erode away. Gradually, the arch becomes smoother and more symmetrical. Over time, though, erosion wins out: the window diameter grows, the pillars grow thinner, and eventually, the arch collapses.

This process is far different from the creation of Michelangelo’s David. There is no natural law that "tells" the hammer where a chin should be, or an arm, or a leg. Granted, Michelangelo had to use natural law; the center of gravity of the statue had to be supported by the legs. The actions of his hammer and chisel had to obey Newton’s laws of motion. But natural law was the servant of his mind. In his mind’s eye, he saw what he wanted the block of marble to become. His mind — not an impersonal process like the weather — told the chisel where to pick.

Not all cases are this intuitively obvious. In the Namibian desert, for instance, some regularly spaced circles have been difficult to explain; did local tribespeople make them, or did they result from the inherent properties of the grass or soil? Another puzzle was recently found under the Sea of Galilee: a huge pile of large boulders. Some archaeologists are convinced they were put there by design: some unknown ancient tribe constructed it as a monument when the lake level was lower. How does one tell?

In an effort to distinguish design from natural causes with a rigorous method, William Dembski in his book The Design Inference presented the "Design Filter." With this filter, preference is given to chance, then to natural law. Intelligent design is only a last resort when those possibilities have been exhausted. This prevents false positives (calling something designed when it isn’t). The burden is on the interpreter to rule out chance and natural law first.

Dembski goes so far as to calculate a "universal probability bound" that sets the bar for design extremely high. To infer design, one would have to exceed a probability of one chance in 10150.

No known event in the entire universe through its entire history would be able to leap that bar by chance. If no natural laws can explain the phenomenon either, design becomes the inference to the best explanation.

Back to those sandstone arches. The chance formation of Delicate Arch as a particular structure is extremely low, so we drop through that stage of the Design Filter. We know of natural laws, however, that can accomplish the task: gravity and erosion. Moreover, we observe arches in all stages of formation by natural processes, from sandstone fins that are getting thin in their centers, through narrow and wide arches, all the way to arches that have collapsed. We stop at that stage of the Design Filter, therefore, and attribute the arch to natural laws. (Exercise: why is the St. Louis Arch different?)

Michelangelo’s David is so improbable that it readily passes through the "chance" explanation. It also passes through the "natural law" stage, because no law of nature tells marble to erode into a human form. Design is already justified at this point, but there’s more reason to support a design inference: specified complexity, or specification. The shape of the marble matches what we know by uniform experience specifies a human form.

Through these and other considerations in the ID literature, we can identify design in the statue, but not in the sandstone arch.

Well, what about a living human being? Is that designed, too? Seemingly, design would be the inference to the best explanation. But Darwinists point to a natural law: natural selection. Shouldn’t that prevent the phenomenon from dropping through to the design inference?

One might think so, except that natural selection is random in the sense of being unguided. It has no goal in mind. Mutations occur at random — that’s chance, clearly, but the environment is random as well, meaning that it does not conspire to produce any particular creature that is able to adapt to it. The "natural law" is, therefore, a phantom; it’s really all about chance. A series of chance events amounts to a chance explanation. No natural law (gravity, electromagnetic forces, etc.) dictates that a human being, or a rose, or a bacterium will arise from chance events. ("Survival" cannot be invoked as a natural law. Unguided, impersonal processes have no concern over whether something survives or not.)

Michael Behe’s argument from irreducible complexity buttresses the design inference for the living human form (and all life forms, down to microbes). A human being is really a hierarchy of irreducibly complex structures. (For just one example, look again at the video we posted of DNA packing and copying.)

Applying all these considerations, we rationally infer design for living things.

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