Saturday, September 8, 2007

Murphy's Law

Murphy's law is an adage in Western culture that broadly states that things will go wrong in any given situation, if you give them a chance. "If there's more than one possible outcome of a job or task, and one of those outcomes will result in disaster or an undesirable consequence, then somebody will do it that way." It is most often cited as "Whatever can go wrong, will go wrong" (or, alternately, "Whatever can go wrong will go wrong, and at the worst possible time, in the worst possible way" or, "Anything that can go wrong, will," or even, "If anything can go wrong, it will, and usually at the most inopportune moment"). The saying is sometimes referred to as Sod's law or Finagle's law which can also be rendered as "Anything that can go wrong, will—at the worst possible moment".


The earliest known versions of Murphy's law are in reference to stage magic. According to research by American Dialect Society member Bill Mullins, Adam Hull Shirk wrote in the September 1928 issue of The Sphinx, which was then the premier journal for magicians in the United States:

It is an established fact that in nine cases out of ten whatever can go wrong in a magical performance will do so. The great professors of the art are not immune from the malignancy of matter and the eternal cussedness of inanimate objects.[1]

The 1928 version was a variation on an existing saying among stage magicians that goes back at least to 1913:

There is an old saying among conjurers that it is impossible for a performer to know a trick thoroughly well until everything that can possibly go wrong with it has gone wrong - in front of an audience.[2]

Association with Murphy

History of Murphy's Law
History of Murphy's Law

According to the book A History of Murphy's Law by author Nick T. Spark, differing recollections years later by various participants make it impossible to pinpoint who first coined the saying Murphy's law. The law's name supposedly stems from an attempt to use new measurement devices developed by the eponymous Edward Murphy. The phrase was coined in adverse reaction to something Murphy said when his devices failed to perform and was eventually cast into its present form prior to a press conference some months later—the first ever (of many) conferences given by Colonel Stapp, The fastest man on earth. These conflicts (a long running interpersonal feud) were unreported until Spark researched the matter. His book expands upon and documents an original four part article published in 2003 (Annals of Improbable Research (AIR)[3]) on the controversy: Why Everything You Know About Murphy's Law is Wrong. From 1948 to 1949, a project known as MX981 took place on Muroc Field (later renamed Edwards Air Force Base) for the purpose of testing the human tolerance for g-forces during rapid deceleration. The tests used a rocket sled mounted on a railroad track with a series of hydraulic brakes at the end.

Initial tests used a humanoid crash test dummy strapped to a seat on the sled, but subsequent tests were performed by medical doctor John Paul Stapp, at that time an Air Force Captain. During the tests, questions were raised about the accuracy of the instrumentation used to measure the g-forces Captain Stapp was experiencing. Edward Murphy proposed using electronic strain gauges attached to the restraining clamps of Stapp's harness to measure the force exerted on them by his rapid deceleration. Murphy was engaged in supporting similar research using high speed centrifuges to generate g-forces. Murphy's assistant wired the harness, and a trial was run using a chimpanzee.

The sensors provided a zero reading, however; it became apparent that they had been installed incorrectly, with each sensor wired backwards. It was at this point that a disgusted Murphy made his pronouncement, despite being offered the time and chance to calibrate and test the sensor installation prior to the test proper, which he declined somewhat irritably getting off on the wrong foot with the MX981 team. In an interview conducted by Nick Spark, George Nichols, another engineer who was present, stated that Murphy blamed the failure on his assistant after the failed test, saying, "If that guy has any way of making a mistake, he will." Nichols' account is that "Murphy's law" came about through conversation among the other members of the team; it was condensed to "If it can happen, it will happen," and named for Murphy in mockery of what Nichols perceived as arrogance on Murphy's part. Another account credits Stapp with espousing it shortly afterwards during a press conference. Others, including Edward Murphy's surviving son Robert Murphy, deny Nichols' account (which is supported by Hill, both interviewed by Spark), and claim that the phrase did originate with Edward Murphy. According to Robert Murphy's account, his father's statement was along the lines of "If there's more than one way to do a job, and one of those ways will result in disaster, then somebody will do it that way." Other documents indicate that Robert A. Murphy himself changed his story several times on several different occasions, including on a lengthy radio station interview which survives[citation needed].

The phrase first received public attention during a press conference in which Stapp was asked how it was that nobody had been severely injured during the rocket sled tests. Stapp replied that it was because they always took Murphy's Law under consideration; he then summarized the law and said that in general, it meant that it was important to consider all the possibilities (possible things that could go wrong) before doing a test and act to counteract them. Thus Stapp's usage and Murphy's alleged usage are very different in outlook and attitude. One is sour, the other an affirmation of the predictable being able to be surmounted, usually by sufficient planning and redundancy. Hill and Nichol's believe Murphy was unwilling to take the responsibility for the device's initial failure (by itself a blip of no large significance) and is to be doubly-damned for not allowing the MX981 team time to validate the sensor's operability and for trying to blame an underling when doing so in the embarrassing aftermath.

The association with the 1948 incident is by no means secure. Despite extensive research, no trace of documentation of the saying as Murphy's law has been found before 1955, when the May - June issue of Aviation Mechanics Bulletin included the line "Murphy's Law: If an aircraft part can be installed incorrectly, someone will install it that way,"[4] and Lloyd Mallan's book, Men, Rockets and Space Rats, referred to: "Colonel Stapp's favorite takeoff on sober scientific laws—Murphy's Law, Stapp calls it—'Everything that can possibly go wrong will go wrong'." The Mercury astronauts in 1962 attributed Murphy's law to U.S. Navy training films.[5]


Murphy's law has taken on many different formulations. In 1952, the proverb, there unnamed, was phrased "Anything That Can Possibly Go Wrong, Does" in the epigraph of John Sack's The Butcher: The Ascent of Yerupaja. A story by Lee Correy in the February 1955 issue of Astounding Science Fiction referred to "Reilly's Law," which it said "states that in any scientific or engineering endeavor, anything that can go wrong will go wrong."[6] Atomic Energy Commission Chairman Lewis Strauss was quoted in the Chicago Daily Tribune on February 12, 1955, saying "I hope it will be known as Strauss' law. It could be stated about like this: If anything bad can happen, it probably will."[7]

Somewhat related to "Finagle's law" or "Sod's law" (see below) are demonstration-related aphorisms, wherein its acknowledged that a demo will fail in front of the intended audience. And that anything untested should not be demonstrated because it will fail.

The spirit of the law

Regardless of the exact composition and origin of the phrase, its spirit embodies the principle of defensive design — anticipating the mistakes the end-user is likely to make. Murphy's g-force sensors failed because there existed two different ways to connect them; one way would result in correct readings, while the other would result in no readings at all. The end-user — Murphy's assistant, in the historical account — had a choice to make when connecting the wires. When the wrong choice was made, the sensors did not do their job properly. Thus, defensive design is sometimes referred to as a "Murphy-proofing" procedure.

In most well-designed technology intended for use by the average consumer, incorrect connections are made difficult; this is the concept of poka-yoke in quality control. For example, the 3.5-inch floppy disk once used in many personal computers will not easily fit into the drive unless it is oriented correctly. In contrast, the yet older 5.25-inch floppy disk could be inserted in a variety of orientations that might damage the disk or drive. The newer CD-ROM and DVD technologies permit one incorrect orientation — the disc may be inserted upside-down, which is harmless to the disc. A defensive designer knows that if it is possible for the disc to be inserted the wrong way, someone will eventually try it. Fatalists observe that even if it seemingly is not possible to perform something incorrectly, someone will eventually manage it. This is often expressed as "Make something idiot-proof, and they will build a better idiot" or "The trouble with making something idiot proof is that idiots are so smart".

From its initial public announcement, Murphy's law quickly spread to various technical cultures connected to aerospace engineering. Before long, variants had passed into the popular imagination, changing as they went. Generally, the spirit of Murphy's law captures the common tendency to emphasize the negative things that occur in everyday life; in this sense, the law is typically formulated as some variant of "If anything can go wrong, it will," a variant often known as "Finagle's law" or "Sod's law" (chiefly British). Laws such as Murphy's are a direct expression of such seeming perversities in the order of the universe.

Some state that Murphy's law cannot operate as a subset of something useful; for example: "It will start raining as soon as I start washing my car, except when I wash the car for the purpose of causing rain." O'Toole's commentary on Murphy's law is: "Murphy was an optimist!" These mutant versions demonstrate Murphy's law acting on itself, or perhaps Finagle's law acting on Murphy's law. These perversions of Murphy's Law can be summed up in Silverman's Paradox: "If Murphy's Law can go wrong, it will."

The Geva correction to the validity of Murphy's Law states that "Murphy's Law applies only in Murphy's systems, i.e. systems in which Murphy's Law is known". In simpler words - if you don't know about it, Murphy's Law does not apply. In a system that comprises only perfect idiots Murphy's Law is invalid, and the system will work perfectly even if it is severely flawed.

Other variations on Murphy's Law

  • Zymurgy's First Law of Evolving Systems Dynamics: Once you open a can of worms, the only way to recan them is to use a bigger can. (Source: The Book of Lists)
  • Hoare's Law of Large Problems: Inside every large problem is a small problem struggling to get out. (Ibid.)

See also

This article is licensed under the GNU Free Documentation License.
It uses material from the Wikipedia article Murphy's Law

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