Good Math, Bad Math

The Real Murphy’s Law


I know better than to attempt to write an april fools day post that really
tries to fool anyone. I’m not a good enough writer to carry that kind of thing off
in a genuinely amusing way. On the other hand, I love april fools day pranks, and
I generally like the silly mood of the day. So I thought I’d write some posts in
the spirit of silliness.

As someone working in engineering, one of my favorite rules is Murphy’s Law. The thing about Murphy’s law is that odds are, what you just thought when I said “Murphy’s Law” is not, in fact, Murphy’s Law. Odds are, you think that Murphy’s law says “If anything can go wrong, it will”. That’s not what it says – Murphy’s law is almost always stated wrong!

The real Murphy’s law: If there’s more than one way to do something,
and one way will result in disaster, then someone will do it that way.

The real Murphy’s Law probably wasn’t even actually created by anyone named Murphy. It dates back to some work done by Colonel John Stapp, a military scientist studying the effects of acceleration on human bodies.

According to the story, Stapp was working with a Major Edward Murphy
on acceleration sleds. The idea of the work was basically to set a sled on
a track, attach a rocket, stick a chair on top with a test subject (generally Colonel Stapp himself) sitting it in, and launch. A bunch of accelerometers were wired to the sled, so that you’d know just what a given experiment did to
the poor Colonel. (The image at the top of this post is a picture of Colonel
Stapp riding the sled during one of these experiments.)

In a famous error, on the first launch of a new, higher acceleration
version of the sled, all of the accelerometers on the sled were
wired backwards, meaning that the experiment provided no information – but Stapp walked away with broken ribs and a detached retina.

Someone – accounts differ as to whether it was Murphy, Stapp, or someone else
– who was talking about the technician who set up the accelerometers, said,
roughly, “If there’s more than one way to do it, and one of them will cause a
disaster, that’s the one that that guy will choose.” It’s most likely Stapp who
restated this as a general principle, and made it into a guiding principle in the
design of their later experiments and test apparatuses. Whoever said it first,
Stapp is clearly the one who popularized it: in press conferences, he told people
that the reason that there were so few serious injuries in their work, despite its
immense danger, was because “they always took Murphy’s law into

What I like about the real Murphy’s law in contrast to the popular one
is where it assigns the blame. The popular Murphy’s law basically says that
the universe itself is pathological – that it’s just the way the world works. The real Murphy’s law places the blame where it really belongs: given the opporunity, people will find a wind to screw things up.

Stapp later came up with another law, which is known as Stapp’s law, which makes that point even clearer: “The universal aptitude for ineptitude makes any human accomplishment an incredible miracle.”


  1. #1 Susan B.
    April 1, 2008

    The real version also has the advantage of allowing you to compensate for it. Just make it so there’s only one way to do something, a way which will not cause a disaster.

    I still think the other version is true, though.

  2. #2 Ambitwistor
    April 1, 2008

    Interestingly, the Genesis spacecraft crash was a reprise of the original Murphy’s Law: it was due to an accelerometer being installed backwards.

  3. #3 Jonathan Vos Post
    April 1, 2008

    My Physics professor wife (a gifted experimentalist and teacher) insists, based on her experience growing up, receiving her first degrees in, and teaching in Scotland, that what Americans call “Murphy’s Law” was popularized years earlier in Great Britain as Sod’s Law.”

  4. #4 QrazyQat
    April 1, 2008

    The real version also has the advantage of allowing you to compensate for it. Just make it so there’s only one way to do something, a way which will not cause a disaster.

    As I understood it, this is exactly what they tried to do, by making it physically impossible, they thought, to do it the wrong way. But it was done the wrong way anyway, apparently by someone who assumed that it was just supposed to be darned difficult.

  5. #5 matt
    April 1, 2008

    As you say, accounts differ. My own preference — formed a good long time ago — is for the Edsel Murphy formulation, as elaborated in Klipstein1967, a spottily-transcribed version of which can be found here (or just google it, as I did).

  6. #6 Torbjörn Larsson, OM
    April 1, 2008

    Just make it so there’s only one way to do something,

    Unfortunately there is a superseding law, which I have no name for:

    “With some effort you can make toys childproof. With considerable effort you can make lab toys prof proof. But there is no way you can make anything student proof.”

  7. #7 Mike Magee
    April 1, 2008

    My favorite variation is: “You can’t make anything idiot-proof because idiots are so ingenious.” -Ron Burn

  8. #8 Janne
    April 1, 2008

    “Make something idiot-proof, and nature will evolve a better idiot.”

  9. #9 RBH
    April 2, 2008

    Let us not forget O’Toole’s commentary on Murphy’s Law (applicable to both versions): “Murphy was an optimist.”

  10. #10 Alex Besogonov
    April 2, 2008

    My favorite quote is:

    “Programming today is a race between software engineers striving to build bigger and better idiot-proof programs, and the Universe trying to produce bigger and better idiots. So far, the Universe is winning.” – Rich Cook

  11. #11 Jonathan Vos Post
    April 3, 2008

    Hard to resist the fortuitious conjunction of “Murphy’s Law” and Math on this thtead.

    Singular moduli spaces and the Rubik’s cube March 22, 2008
    Posted by Ben Webster in Algebraic Geometry, rubik’s cube, talks.


    I’m currently in Maryland at a conference to celebrate the 62nd birthday of John Millson (why 62? Beats me. I guess people like him so much they couldn’t wait for 65).

    Ravi Vakil is talking about “Murphy’s Law” in algebraic geometry, which was ably summed up by Harris and Morrison (not our Morrison) as “There is no geometric configuration so horrible that it does not appear in a Hilbert scheme.” A Hilbert scheme is a moduli space of subvarieties of \mathbb{P}^n, so it’s a very natural object to look at in algebraic geometry, and thus it’s very upsetting that it’s as singular as you can possibly imagine. This means all kinds of horrifying objects must exist, like surfaces in characteristic 31 which deform to characteristic 0 to 43rd order, but no further. Yuck!

  12. #12 John Armstrong
    April 3, 2008

    Susan astutely points out the possibility of taking Murphy’s Law into consideration and nobody follows up with the fact that many connectors on the back of the computers you’re probably reading this on RIGHT NOW are trapezoids?

    Man, I run off to California for one day and…

  13. #13 bernarda
    April 4, 2008

    It reminds me of a statement by Winston Churchill to the effect: Americans will always do the right thing, after they have tried everything else.

  14. #14 Lim Ee Hai
    April 4, 2008

    The real Murphy’s Law, at least, revealed the nature of human, that is, to challenge the boundaries. Without Murphy’s Law, we will be complacent.

  15. #15 iand
    April 14, 2008

    Jonathon: Sodd’s law actually states “When a person attempts a task, he or she will be thwarted in that task by the unconscious intervention of some other presence (animate or inanimate). Nevertheless, some tasks are completed, since the intervening presence is itself attempting a task and is, of course, subject to interference.” This is different to Murphy’s law. I’m sorry, but your Physics professor wife was wrong.

    By the way, Sodd was a real person … but most people mis-spell his name, assuming that “sod” is here used in its British equivilent to “frak”.

  16. #16 Kent Lyman
    April 15, 2008

    It is O’Neals corollary which states “Murphy was an optimist”.

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