How Murphy's Law Works

Preventing Murphy's Law

While most of us appreciate Murphy's Law for its ability to explain our sense of helplessness during certain events, others see it as a tool. At least one person sees it as a mathematical equation that can predict the chances of processes going awry. Joel Pel, a biological engineer at the University of British Columbia created a formula that predicts the occurrence of Murphy's Law.

The formula uses a constant equal to one, a factor that is unconstant, and a few variables. In this formula, Pel uses the importance of the event (I), the complexity of the system involved (C), the urgency of the need for the system to work (U) and the frequency the­ system is used (F).

In an essay he wrote for Science Creative Quarterly, Pel uses the example of predicting the occurrence of Murphy's Law when a driver needs to drive his Toyota Tercel a distance of about 60 miles to his home in a rainstorm without the clutch going out. Using Murphy's Equation, Pel comes up with an answer of 1, meaning the clutch on the Tercel will definitely go out in a rainstorm. While anyone familiar with a Tercel might've seen that coming, it's somehow comforting to know that it can also be predicted mathematically [source: Science Creative Quarterly].

Murphy's Law reminds engineers, computer programmers and scientists of a simple truth: systems fail. In some cases, a system's failure means that the experiment must be repeated. In other cases, the results of a failure can be much more costly.

NASA has learned this over and over again. The space agency has had numerous failures, and although the number is proportionately small to its successes, the failures are often very costly. Ironically, in the case of one unmanned orbiting vessel, a set of sensors had two ways of being connected and -- just as with Murphy's original Gee Whiz test-- the sensors were all connected incorrectly. When the sensors failed to operate the way they were designed, the parachutes that were meant to slow the spacecraft down didn't open, and the orbiter crashed into the desert [source: MSNBC].

It's an instance like this, in conjunction with an awareness of Murphy's Law that has caused designers to install fail-safes. There are examples of fail-safes all around us. Some are systems that use limited choices to reduce errors, like the mismatched prong sizes on an electrical plug. Others are mechanisms that prevent matters from going from bad to worse, like lawnmowers that have levers that must be held down in order for the mower to operate. If the person operating the mower lets go of the lever, the lawnmower stops running.

Fail-safes are also referred to as "idiot-proof." But Murphy's Law still has a tendency to strike, even when care has been taken to ensure against failure or catastrophe. This leads us to the last law we'll relate to Murphy's: Grave's Law, which states, "If you make something idiot-proof, the world will create a better idiot."

For lots more information on Murphy's Law, including related articles and links, check out the next page.

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More Great Links


  • Hecht, Jeff. "Murphy's Law honoured - 50 years late." New Scientist. October 3, 2003.
  • Pel, Joel. "The Murphy's Law Equation." The Science Creative Quarterly. September 07-April 08.
  • Spark, Nick T. "Why Everything You Know About Murphy's Law Is Wrong." Improbable Research.
  • "Murphy's Law."
  • "Murphy's Law." Socyberty.
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  • "Murphy's Laws and Corollaries."
  • "Murphy's Laws Origin."