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James Randi Educational Foundation

An Encyclopedia of Claims, Frauds, and Hoaxes of the Occult and Supernatural

Introduction | "R" Reading | Curse of the Pharaoh | End-of-the-World Prophecies

Index | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | Y | Z

parsimony Aside from its usual meaning of “frugality,” this word expresses a very important philosophical and logical concept. Also known as Occam's (or Ockham's) razor, it is a philosophical principle usually credited to William of Occam (1285-1347/9), and Galileo used it when he preferred the heliocentric solar system over a geocentric one. Sir W. Hamilton (1788-1856) stated it:  


      The law of Parcimony [sic], which forbids, without necessity, the multiplication of entities, powers, principles, or causes; above all, the postulation of an unknown force, where a known impotence can account for the effect.

      (The rule was originally stated by Occam as, “Entia non sunt multiplicanda praeter necessitatem.”)
      In effect, this rule states that if there exists more than one answer to a problem or a question, and if, for one answer to be true, well-established laws of logic and science must be re-written, ignored, or suspended in order to allow it to be true, and for the other answer to be true no such accommodation need be made, then the simpler——the second——of the answers is much more likely to be correct.
      Here is an example of a problem:  

      The claim: that a person can cause an ordinary spoon to bend merely by looking at it, using psychic powers that have not been established and which would violate many known rules (conservation and transfer of energy, etc.) and cause those basic laws of science to be rewritten.  
      There are two explanations available: one says that these basic physical laws have been suspended in this case——a unique event never before known in history——and the other says that the performer has employed sleight of hand and/or deceptive optical principles and/or psychological misdirection to provide the illusion of the spoon bending without the use of ordinary physical force.

      The second of the two explanations is much more likely to be true.
      To substitute another phenomenon for the previous example:  

      The claim: that a magician can saw a woman in two pieces and then restore her using special powers that have not been established and which would violate many known rules (physiological, biological, etc.) and cause those basic laws of science to be rewritten.  
      There are two explanations available: one says that these basic physical laws have been suspended in this case——a unique event never before known in history——and the other says that the performer has employed deceptive optical and/or mechanical principles to provide the illusion of the woman having been sawn in two and then restored alive.

      In this case, which explanation is much more likely to be true? Is the likelihood not just as strong in both cases?



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