This is a list of aphorisms applicable to IT. In my career I had referred to them more than once.
Planning is everything
I tell this story to illustrate the truth of the statement I heard long ago in the Army: Plans are worthless, but planning is everything. There is a very great distinction because when you are planning for an emergency you must start with this one thing: the very definition of "emergency" is that it is unexpected, therefore it is not going to happen the way you are planning.
Dwight D. Eisenhower. From a speech to the National Defense Executive Reserve Conference in Washington, D.C. (November 14, 1957) ; in Public Papers of the Presidents of the United States, Dwight D. Eisenhower, 1957, National Archives and Records Service, Government Printing Office, p. 818 : ISBN 0160588510, 9780160588518
Duck test
If it looks like a duck, swims like a duck, and quacks like a duck, then it probably is a duck.
Popularized by 1950 United States ambassador to Guatemala, Richard Cunningham Patterson Jr., accusing Guatemala's goverment of being a communist one.
Jesus visits the home of Martha and Mary
She came to him and asked, “Lord, don’t you care that my sister has left me to do the work by myself? Tell her to help me!” “Martha, Martha,” the Lord answered, “you are worried and upset about many things, but few things are needed—or indeed only one. Mary has chosen what is better, and it will not be taken away from her.”
Permanent temporary solutions
... nothing is so permanent as a temporary government program.
Tyranny of the status quo, 1984, by Milton Friedman and Rose Friedman
Truth is no barrier
Never let the truth get in the way of a good story.
Another quote by Mark Twain. Why not?
Keynes' Markets irrationality
Markets can remain irrational longer than you can remain solvent.
John Maynard Keynes. Though maybe apocryphal.
Golden hammer
If the only tool you have is a hammer, it is tempting to treat everything as if it were a nail.
Abraham Maslow. The Psychology of Science: A Reconnaissance (1966).
The Dunning-Kruger effect
... difficulties in recognizing one's own incompetence lead to inflated self-assessments.
Kruger, J., & Dunning, D. (1999). Unskilled and unaware of it: How difficulties in recognizing one's own incompetence lead to inflated self-assessments. Journal of Personality and Social Psychology, 77(6), 1121–1134
Not simpler than necessary
Everything should be made as simple as possible, but not simpler.
Based on Albert Einstein's works, but unsure Einstein wrote it like that.
Perfection, by Saint-Exupéry
Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away.
Antoine de Saint-Exupéry
Make one thing well (UNIX philosophy)
Make each program do one thing well.
Douglas McIlroy, Bell System Technical Journal, Vol. 57, No. 6, July-August 1978, page 1902
Repeated lies
If you repeat a lie often enough, it becomes accepted as truth
Leslie Lamport and distributed systems
A distributed system is one in which the failure of a computer you didn't even know existed can render your own computer unusable.
Email by Leslie Lamport in May 28th 1987.
The Peter principle
In a hierarchy, every employee tends to rise to his level of incompetence.
The Peter Principle, Laurence J. Peter and Raymond Hull, 1969-1970, Pan Books
Monkeys and bananas (and cold water)
In an experiment a group of monkeys are placed in a room with a ladder and on top of the ladder some bananas.
When a monkey tries to climb, all monkeys receive jets of cold water as punishment. Over time none of the monkeys climbs the ladder.
A new monkey is introduced, replacing one of the initial monkeys. When the new one tries to get the bananas, all monkeys in the group fight the daring monkey to prevent the cold water punishment.
The process is repeated: a new monkey is exchanged and all remaining monkeys teach the lesson (the hard way) to the new monkey; the other new monkey -that has never recevied the shower of cold water- also participates in teaching the lesson.
All monkeys are exchanged, and none of the original bunch remains. But the monkeys will not allow any newcomer to try reaching the bananas, despite they have not suffered the cold water punishment themselves.
Free interpretation of the investigations by Gordon R. Stephenson, Stephenson, G. R. (1967), Cultural Acquisition of a Specific Learned Response Among Rhesus Monkeys – In: Starek, D., Schneider, R., and Kuhn, H. J. (eds.), Progress in Primatology, Stuttgart: Fischer, pp. 279-288.
Goodhart's law
When a measure becomes a target, it ceases to be a good measure.
Improving Ratings, Audit In The British University System, 1997, Marilyn Strathern
Monetary Relationships: A View from Threadneedle Street. Papers in Monetary Economics (Reserve Bank of Australia), 1975, Charles Goodhart
Conway's law
Any organization that designs a system (defined broadly) will produce a design whose structure is a copy of the organization's communication structure.
Originally submitted in 1967 as How Do Committees Invent? to Harvard Business Review, but rejected. Published in Datamation maganize in April 1968. See bibliography description by the author himself here.
The root of all evil
... premature optimization is the root of all evil (or at least most of it) in programming.
Computer Programming as an Art, Association for Computing Machinery (ACM) 1974 Turing Award Lecture, Donald Knuth.
Robustness Principle (Postel's law)
... be conservative in what you do, be liberal in what you accept from others.
Rule of least power
... choosing the least powerful language suitable for a given purpose.
Gall's law
A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over with a working simple system.
General systemantics: How Systems Really Work and How They Fail, 1975, John Gall.