Murphy’s Law prov.

The correct, original Murphy’s Law reads: “If there are two or more ways to do something, and one of those ways can result in a catastrophe, then someone will do it.” This is a principle of defensive design, cited here because it is usually given in mutant forms less descriptive of the challenges of design for lusers. For example, you don’t make a two-pin plug symmetrical and then label it `THIS WAY UP’; if it matters which way it is plugged in, then you make the design asymmetrical (see also the anecdote under magic smoke).

Edward A. Murphy, Jr. was one of the engineers on the rocket-sled experiments that were done by the U.S. Air Force in 1949 to test human acceleration tolerances (USAF project MX981). One experiment involved a set of 16 accelerometers mounted to different parts of the subject’s body. There were two ways each sensor could be glued to its mount, and somebody methodically installed all 16 the wrong way around. Murphy then made the original form of his pronouncement, which the test subject (Major John Paul Stapp) quoted at a news conference a few days later.

Within months `Murphy’s Law’ had spread to various technical cultures connected to aerospace engineering. Before too many years had gone by variants had passed into the popular imagination, changing as they went. Most of these are variants on “Anything that can go wrong, will”; this is correctly referred to as Finagle’s Law. The memetic drift apparent in these mutants clearly demonstrates Murphy’s Law acting on itself!

Finagle’s Law n.

The generalized or `folk’ version of Murphy’s Law, fully named “Finagle’s Law of Dynamic Negatives” and usually rendered “Anything that can go wrong, will”. May have been first published by Francis P. Chisholm in his 1963 essay “The Chisholm Effect”, later reprinted in the classic anthology “A Stress Analysis Of A Strapless Evening Gown: And Other Essays For A Scientific Eye” (Robert Baker ed, Prentice-Hall, ISBN 0-13-852608-7).

The label `Finagle’s Law’ was popularized by SF author Larry Niven in several stories depicting a frontier culture of asteroid miners; this `Belter’ culture professed a religion and/or running joke involving the worship of the dread god Finagle and his mad prophet Murphy. Some technical and scientific cultures (e.g., paleontologists) know it under the name `Sod’s Law’; this usage may be more common in Great Britain.

One variant favored among hackers is “The perversity of the Universe tends towards a maximum” (but see also Hanlon’s Razor).