June 30, 2012 | David F. Coppedge

Explanatory Filter in Action: Fairy Circles in Africa

The old “crop circle” craze fanned the curiosity of many, till humans were filmed making them.  Now, scientists have a different circle mystery, and they’re stumped.

The “Explanatory Filter” devised by William Dembski (see IDEAcenter.org) includes intelligent causes as a last resort, once natural law and chance are ruled out.  Often, it takes time to work through the filter.  When the crop circle craze hit, the simplicity of the circles suggested a natural cause at first.  But then the patterns got more and more elaborate, exhausting the probabilistic resources of chance or natural law (or both) to account for them.  In addition, they exhibited complex specified information, like mathematical forms only minds would comprehend.  This shows that scientists intuitively use the filter, even if they don’t accept Dembski’s intelligent design theory.

A test case is underway in Africa.  Live Science reported that researchers are stumped at mysterious circles out in the middle of nowhere, 111 miles from the nearest village.  “In the sandy desert grasslands of Namibia in southern Africa, mysterious bare spots known as “fairy circles” will form and then disappear years later for no reason anyone can determine,” reporter Stephanie Pappas wrote.  “A new look at these strange patterns doesn’t solve the wistful mystery but at least reveals that the largest of the circles can linger for a lifetime.”

Geometric circles are familiar in the plant kingdom.  Some mushrooms grow in circles called “fairy rings.”  Some superstitious people coming across these near-perfect circles of mushrooms jumped to the conclusion that mystical spirits were at work in the forest (thus the name).  They didn’t use the explanatory filter correctly; it shows that rushing to a design inference can be unwarranted.  Some grasses and bushes can also be found growing in circles.  The usual explanation is that the organism moves outward in all directions as nutrients in the center are exhausted.  That explanation, though, does not fit the African fairy circles.  They cannot yet be explained by nutrients, toxic vapors, termites or other natural causes so far examined.

“The why question is very difficult,” said study researcher Walter Tschinkel, a biologist at Florida State University. “There are a number of hypotheses on the table, and the evidence for none of them is convincing.”

This is an example of the Explanatory Filter in action (though Tschinkel should have said the how question, not the why question–the province of philosphy).  Natural causes are the default, and will most likely be found for such simple geometric shapes.  These circles, ranging from 12 to 40 feet in diameter, are not perfect, some are oblong, and they appear randomly spaced. Still, since it is a “persistent enigma,” scientists cannot and should not rule out design (i.e., that unseen tribes have a purpose for clearing the ground in an unusual way).

Researchers are treating this like a puzzle-solving expedition that, even though unlikely to be solved soon, will yield an answer eventually.  “That’s science, isn’t it?” Tschinkel remarked.  “If you knew the answer ahead of time, it wouldn’t be much fun.”

There’s nothing unusual about approaching a scientific puzzle Dembski’s way.  The Explanatory Filter is an intuitive puzzle-solving method that can be mathematically formalized, as Dembski has done.  The controversy comes when evolutionists do think they know the answer ahead of time, and it is “not design.”  Yet they will turn around and accept the design inference for crop circles and SETI.

We believe a natural explanation will be found for these African “fairy circles,” but the goal of every scientist should be to keep an open mind, consider all the reasonable causes (including intelligent causes, which we can determine from uniform experience and probability), and to follow the evidence where it leads.

Teaching Aid:  Present images of circles found in nature to students, and help them determine which ones have natural causes and which have intelligent causes, using the Explanatory Filter.  Examples could include: (1) Mushroom fairy rings, (2) Native American medicine wheel patterns in the desert, (3) Circular farm fields as seen from aircraft, watered by radially rotating irrigation pipes; (4) Stonehenge; (5) planetary nebulae; (6) Mars rocks with circles etched on them cut by the NASA rover’s cutting tool; (7) circles in sand made by bending grasses blown by winds; like a compass; (8) radiohalos in granite.  Finally, show the Namib “fairy circles” as an example of explanatory work in progress.

Exercise:  Find historical examples of secular scientists or evolutionists allowing for an intelligent design inference after ruling out natural law and chance (SETI being a classic example).  List some scientific fields that routinely infer intelligent causes (e.g., archaeology).

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