Occam’s Razor is a principle of logic and philosophy that is perhaps most appropriately stated as “when you have two competing theories which make exactly the same prediction, the one that is simpler is the better.” It was popularized and extensively applied by a 14th-century logician and Franciscan friar named William of Occam (or Ockham)(1284-1347). Occam’s Razor describes only what is more likely. It is always subject to confirmation by experimentation. It only applies when the two competing theories make exactly the same prediction.

An example of the proper use of Occam’s Razor relates to the crop circles that appeared in England in the early 1970s. At first, circles, and then more intricate designs appeared as depressed grass or plants in fields in England. There was much speculation that they were caused by aliens coming to Earth in spaceships. Articles and books were written about them. Quasi-scientific missions set out to discover the aliens in the act. Occam’s Razor told the skeptics that the simplest hypothesis (i.e., the designs were man-made) was the most likely. The alternative, aliens mounting an expedition from a far away stellar system to Earth, arriving, making the designs and then disappearing, all undetected, was more complicated. In fact, after several years, two English pranksters revealed that they had cooked up the whole thing at the local pub over two pints of Guinness. See Carl Sagan’s article Crop Circles and Aliens: What’s The Evidence? Parade Magazine (The Baltimore Sun); Sunday, December 3, 1995. pp. 10-12, 17.