資料來源 : Free On-Line Dictionary of Computing

Murphy's Law
     
         (Or "Sod's Law") 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 US 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
        sometimes referred to as {Finagle's Law}.  The memetic drift
        apparent in these mutants clearly demonstrates Murphy's Law
        acting on itself!
     
        [{Jargon File}]
     
        (1998-02-14)