Murphy's Computer Law

• Murphy never would have used one.
• Murphy would have loved them.

The remaining work to finish in order to reach your goal increases as the deadline approaches.

Adding manpower to a late software project makes it later.

It's morally wrong to allow naive end users to keep their money.

When all else fails, read the instructions.

Any sufficiently advanced technology is indistinguishable from magic.

The higher the "higher-ups" are who've come to see your demo, the lower your chances are of giving a successful one.

Every task takes twice as long as you think it will take. If you double the time you think it will take, it will actually take four times as long.

There is always one item on the screen menu that is mislabeled and should read "ABANDON HOPE ALL YE WHO ENTER HERE."

A bad sector disk error occurs only after you've done several hours of work without performing a backup.

No matter how large and standardized the marketplace is, IBM can redefine it.

• To study an application best, understand it thoroughly before you start.
• Always keep a record of data. It indicates you've been working.
• Always draw your curves, then plot the reading.
• In case of doubt, make it sound convincing.
• Program results should always be reproducible. They should all fail in the same way.
• Do not believe in miracles. Rely on them.

Blessed is the end user who expects nothing, for he/she will not be disappointed.

• At the source of every error which is blamed on the computer you will find at least two human errors, including the error of blaming it on the computer.
• Any system which depends on human reliability is unreliable.
• Undetectable errors are infinite in variety, in contrast to detectable errors, which by definition are limited.
• Investment in reliability will increase until it exceeds the probable cost of errors, or until someone insists on getting some useful work done.

The amount of expertise varies in inverse proportion to the number of statements understood by the general public.

Your "IBM PC-compatible" computer grows more incompatible with every passing moment.

The first myth of management is that it exists.

• Any given program, when running, is obsolete.
• If a program is useful, it will have to be changed.
• If a program is useless, it will have to be documented.
• Any given program will expand to fill all available memory.
• The value of a program is proportional to the weight of its output.
• Program complexity grows until it exceeds the capability of the programmer who must maintain it.
• Make it possible for programmers to write programs in English, and you will find that programmers cannot write English.

Inside every large program is a small program struggling to get out.

A program generator creates programs that are more "buggy" than the program generator.

There's never time to do it right, but always time to do it over.

If there is a possibility of several things going wrong, the one that will cause the most damage with be the one to go wrong.

Things get worse under pressure.

The first ninety percent of the task takes ninety percent of the time, and the last ten percent takes the other ninety percent.

The man who can smile when things go wrong has thought of someone he can blame it on.

An ounce of image is worth a pound of performance.

Variables won't, constants aren't.

Murphy was an optimist.

The solution to a problem changes the problem.

Inside every complex and unworkable program is a useful routine struggling to be free.

Judgment comes from experience; experience comes from poor judgment.

It works better if you plug it in.

Build a system that even a fool can use, and only a fool will want to use it.

• Given an problem containing N equations, there will be N+1 unknowns.
• An object or bit of information most needed will be least available.
• Any device requiring service or adjustment will be least accessible.
• Interchangeable devices won't.
• In any human endeavor, once you have exhausted all possibilities and fail, there will be one solution, simple and obvious, highly visible to everyone else.
• Badness comes in waves.

• After months of training and you finally understand all of a program's commands, a revised version of the program arrives with an all-new command structure.
• After designing a useful routine that gets around a familiar "bug" in the system, the system is revised, the "bug" is taken away, and you're left with a useless routine.
• Efforts in improving a program's "user friendliness" invariably lead to work in improving user's "computer literacy."
• That's not a "bug", that's a feature!

An expert is a person who avoids the small errors while sweeping on to the grand fallacy.

If builders built buildings the way programmers write programs, then the first woodpecker that came along would destroy civilization.

Once you open a can of worms, the only way to recan them is to use a larger can.

As soon as a still-to-be-finished computer task becomes a life-or-death situation, the power fails.

also available as...

• PDF or Typst source
• PNG
• PLAINTEXT

what?

I saw these on a poster at the Connections Museum Seattle in December 2024. The original poster has a copyright notice with the year 1984 and names Celestial Arts, with a mailing address in Berkeley, CA, but I haven't looked into it more. It also says that it was compiled by Tony Bove and Cheryl Rhodes, and designed by Kim Gale.

As you can guess, I wanted a copy for myself. I also wanted an excuse to try Typst. So I found a picture of the poster, transcribed it, typeset it, and printed it. It's taped up near my desk. Here's a picture of the original that I stole from an ebay listing asking for more than the price of my time:

Some of these do feel a little archaic. But it's been four decades, and while many things have changed, it seems many things have stayed the same. Last year I started my own collection of more recent programming aphorisms that I like. Maybe someday I'll make my own poster. For now, please communicate *your* favorite computer law with me telepathically. ♦︎

Update: I have these boxes now, so you can do it digitally instead: