Murphy's law is an adage in Western culture that broadly states, "if anything can go wrong, it will." It is also cited as: "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"; "Anything that can go wrong, will," the similar "Whatever can go wrong, will go wrong"; or, "Whatever can go wrong will go wrong, and at the worst possible time, in the worst possible way". In a less dramatic fashion, the law can be expressed as "Anything that has a probability of happening greater than 0 can and will happen. No exceptions." The saying is sometimes referred to as Sod's law or Finagle's law.
I never had a slice of bread,
Particularly large and wide,
That did not fall upon the floor,
And always on the buttered side.
Recent research in this area has been carried on to a significant extent by members of the American Dialect Society. ADS member Stephen Goranson has found a version of the law, not yet generalized or bearing that name, in a report by Alfred Holt at an 1877 meeting of an engineering society:
It is found that anything that can go wrong at sea generally does go wrong sooner or later, so it is not to be wondered that owners prefer the safe to the scientific.... Sufficient stress can hardly be laid on the advantages of simplicity. The human factor cannot be safely neglected in planning machinery. If attention is to be obtained, the engine must be such that the engineer will be disposed to attend to it.
It is an experience common to all men to find that, on any special occasion, such as the production of a magical effect for the first time in public, everything that can go wrong will go wrong. Whether we must attribute this to the malignity of matter or to the total depravity of inanimate things, whether the exciting cause is hurry, worry, or what not, the fact remains.
Murphy's law emerged in its modern form no later than 1952, as an epigraph to a mountaineering book by Jack Sack, who described it as an "ancient mountaineering adage":
Anything that can possibly go wrong, does.
There were a number of particularly delightful incidents. There is, for example, the physicist who introduced me to one of my favorite "laws", which he described as "Murphy's law or the fourth law of thermodynamics" (actually there were only three last I heard) which states: "If anything can go wrong, it will".
The name "Murphy's law" was not immediately secure. 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". 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".
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. 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)) 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.
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 Nichols 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 1952 (see above). The next citations are not found until 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," 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.
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.
Another alternative origin to Murphy's Law attributes the saying to an accident. Although unsubstantiated, it has been discussed and asserted by former colleagues of the person named Murphy in this account. To wit: Ben Murphy, in the mid 1930s, was a radio broadcasting engineer who was often sent on assignment to provide technical support for remote radio broadcasts. Supposedly, he worked for the Pacific regional division of the (then) NBC radio network. Murphy, an assistant, and an announcer were sent on assignment to the area of Capistrano, California to broadcast live via special telephone line hookup, the famous and annual return of the Cliff Swallows (small birds) to that area from their winter migration to Argentina. A noted phrase evoked by this regular migratory habit was coined: "as reliable as the return of the swallows to Capistrano".
After lugging heavy electronic equipment up a small hillside, stringing hundreds of feet of communications cabling, being soaked by unexpected rainfall, beset by angry townspeople, stung by various insects and generally being harassed by nature and humans alike, Murphy and his companions were attempting to plant a microphone in the rock cliffs surrounding the town of San Juan Capistrano in order to capture the sound of the beating of thousands of birds' wings as the swallows returned to make their summer nests. Murphy lost his footing and tumbled down the cliff to a small flat area. Although alive, he was injured, breaking several bones and sustaining multiple scrapes and other wounds.
He was rescued and transported to hospital, and en route he learned that they had missed the annual event by several days; the birds had returned and had made their nests a week earlier, so all Murphy's hard work and subsequent injuries were essentially in vain. Ben Murphy was supposedly overheard to say (in response to comments from his two fellow broadcasters) that: "If anything could have gone wrong with this assignment, it sure did!" Although no further mention is ever made in radio broadcasting annals, Murphy is said to have survived and continued to work for NBC as a remote broadcast engineer until his retirement, some time in the 1950s.
A lesser-known addendum to Murphy's Law is Flanagan's Precept, which categorically states that both Murphy and Finagle were incurable optimists. Sometimes stated as "nothing is that predictable", meaning that one cannot use the inevitability of Murphy's law to avoid its consequences.
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.
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 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", "The trouble with trying to make something idiot proof is that idiots are so smart", "A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools", "Anything which seems idiot-proof has not yet encountered a sufficiently determined idiot", or "nothing is fool-proof to a sufficiently talented fool".
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).
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."
Author Arthur Bloch has compiled a number of books full of corollaries to Murphy's law and variations thereof. These include the original Murphy's Law (1977) and Murphy's Law Book Two (1980), which are very general in scope, and the domain-specific volumes, Murphy's Law: Doctors: Malpractice Makes Perfect and Murphy's Law: Lawyers: Wronging the Rights in the Legal Profession!. Later, a collection of three volumes was also published. This led to a corollary: "Stores selling Volume I have not heard of Volume II; stores selling Volume II have run out of Volume I".
Murphy's Law is sometimes also presented as a life philosophy. Also embodying defensive design, many simply see it as a way of saying in the approach of anything whatsoever that could have a possible flaw, then it is always within good measure to make the necessary precautions to make sure that those flaws can not happen. Many see it as the initial meaning behind what Murphy was saying, a simple philosophy of defensive design that has been highly misinterpreted. However, this is left open to controversy.
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 do not know about it, Murphy's Law does not apply. In a system that comprises perfect idiots only, Murphy's Law is invalid, and the system will work perfectly even if it is severely flawed.
Anecdotally, it has also been suggested (primarily by those in the technical support field) that some individuals appear to manifest a Murphy Field. When these individuals are around systems that function normally, the systems suddenly fail or operate erratically. On the other hand, it is often noted that computer maintainance technicians seem to exhibit an anti-Murphy Field: computers that malfunction in their absence tend to run smoothly when one tries to show them what the problem is.