scientific skepticism

August 3, 2009

Dowsing (credit: skepdic.com)

(I realize I may be preaching to the choir here, but I still feel this topic deserves some text.)

One of the most useful (I mean in every day life) aspects of the scientific method is the tradition of reasoned skepticism that it teaches us.

If you live in the country, there’s a good chance that you get your water from a well. The person who dug your well had to decide where to place it, and it’s likely that he or she decided that location using dowsing (sometimes called witching or divining).

Dowsing is the practice of using metal rods or a willow switches to tell the user where something (usually water) is when the user is walking around. Many, many people swear by it to find water and try to explain it with (science-esqe) “electric fields” and “vibrations,” but really it’s no more than well-ingrained superstition. (For a more favorable explanation, go here.)

Dowsers understandably believe that the technique works because the place that the metal rods tell them has water, low and behold, usually has water. This fact in itself is not a proper test, nor is the vast, vast body of anecdotal evidence that accompanies old superstitions like this. To properly test this hypothesis, what do we need?….a control. We need some sort of benchmark to ascertain that the results of the dowsers are something more than just random chance.

Such is dowsing’s prevalence that a number of such studies have actually been done to ascertain its effectiveness. R. A. Foulkes published a study in Nature (need subscription or other means for full article) performed by the British Army and Ministry of Defense that shows that dowsing yields no better results than random chance. Others have published to the same effect:
– M. Martin (1983-1984). “A new controlled dowsing experiment.” Skeptical Inquirer. 8(2), 138-140
– D. Smith (1982). “Two tests of divining in Australia.” Skeptical Inquirer. 4(4). 34-37.]
(thanks to http://www.skepdic.com/dowsing.html for the links)

A small number of studies were performed that seem to confirm the efficacy of dowsing, the most comprehensive of which was done by Hans-Dieter Betz (part 1 and part 2). Unfortunately, though, J.T. Enright has pretty thoroughly discredited that study.

The scientific literature seems pretty clear.

I don’t mean to mock or pillory dowsers. Instead, I hope to show how very common practices, with wide bodies of anecdotal evidence, can persist even today without actually being true. So the next time someone makes a claim that intuitively strikes you as odd, use the tools science gives you unpack the truth.

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