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Edsger W. Dijkstra

66 quotes

“For a number of years I have been familiar with the observation that the quality of programmers is a decreasing function of the density of go to statements in the programs they produce. More recently I discovered why the use of the go to statement has such disastrous effects, and I became convinced that the go to statement should be abolished from all "higher level" programming languages.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“Our intellectual powers are rather geared to master static relations and ... our powers to visualize processes evolving in time are relatively poorly developed. For that reason we should do (as wise programmers aware of our limitations) our utmost to shorten the conceptual gap between the static program and the dynamic process, to make the correspondence between the program (spread out in text space) and the process (spread out in time) as trivial as possible.”
Edsger W. Dijkstra (1930–2002) first seen 1968 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1968) "A Case against the GO TO Statement" cited in: Bill Curtis (1981) Tutorial, human factors in software development. p. 109.
“Testing shows the presence, not the absence of bugs”
Edsger W. Dijkstra (1930–2002) first seen 1969 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1969) J.N. Buxton and B. Randell, eds, Software Engineering Techniques, April 1970. Report on a conference sponsored by the NATO Science Committee, Rome, Italy, 27–31 October 1969. p. 16. Possibly the earliest…
“A convincing demonstration of correctness being impossible as long as the mechanism is regarded as a black box, our only hope lies in not regarding the mechanism as a black box.”
Edsger W. Dijkstra (1930–2002) first seen 1970 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1970) "Notes On Structured Programming" (EWD249), Section 3 ("On The Reliability of Mechanisms"), p. 5.
“When we take the position that it is not only the programmer's responsibility to produce a correct program but also to demonstrate its correctness in a convincing manner, then the above remarks have a profound influence on the programmer's activity: the object he has to produce must be usefully structured.”
Edsger W. Dijkstra (1930–2002) first seen 1970 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1970) "Notes On Structured Programming" (EWD249), Section 3 ("On The Reliability of Mechanisms"), p. 6.
“The art of programming is the art of organizing complexity, of mastering multitude and avoiding its bastard chaos as effectively as possible.”
Edsger W. Dijkstra (1930–2002) first seen 1970 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1970) "Notes On Structured Programming" (EWD249), Section 3 ("On The Reliability of Mechanisms"), p. 7.
“Program testing can be used to show the presence of bugs, but never to show their absence!”
Edsger W. Dijkstra (1930–2002) first seen 1970 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1970) "Notes On Structured Programming" (EWD249), Section 3 ("On The Reliability of Mechanisms"), corollary at the end.
“The competent programmer is fully aware of the strictly limited size of his own skull; therefore he approaches the programming task in full humility, and among other things he avoids clever tricks like the plague.”
Edsger W. Dijkstra (1930–2002) first seen 1972 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1972) The Humble Programmer (EWD340).
“Another two years later, in 1957, I married and Dutch marriage rites require you to state your profession and I stated that I was a programmer. But the municipal authorities of the town of Amsterdam did not accept it on the grounds that there was no such profession. And, believe it or not, but under the heading "profession" my marriage act shows the ridiculous entry "theoretical physicist"!”
Edsger W. Dijkstra (1930–2002) first seen 1972 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1972) The Humble Programmer (EWD340).
“Automatic computers have now been with us for a quarter of a century. They have had a great impact on our society in their capacity of tools, but in that capacity their influence will be but a ripple on the surface of our culture, compared with the much more profound influence they will have in their capacity of intellectual challenge without precedent in the cultural history of mankind.”
Edsger W. Dijkstra (1930–2002) first seen 1972 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1972) The Humble Programmer (EWD340).
“Please don't fall into the trap of believing that I am terribly dogmatic about [the go to statement]. I have the uncomfortable feeling that others are making a religion out of it, as if the conceptual problems of programming could be solved by a simple trick, by a simple form of coding discipline!”
Edsger W. Dijkstra (1930–2002) first seen 1973 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1973) in personal communication to Donald Knuth, quoted in Knuth's "Structured Programming with go to Statements".
“Don't blame me for the fact that competent programming, as I view it as an intellectual possibility, will be too difficult for "the average programmer" — you must not fall into the trap of rejecting a surgical technique because it is beyond the capabilities of the barber in his shop around the corner.”
Edsger W. Dijkstra (1930–2002) first seen 1975 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1975) Comments at a Symposium (EWD 512).
“Are you quite sure that all those bells and whistles, all those wonderful facilities of your so-called "powerful" programming languages belong to the solution set rather than to the problem set?”
Edsger W. Dijkstra (1930–2002) first seen 1976 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1976) A Discipline of Programming, Prentice-Hall, 1976, p. xiv.
“Some people found error messages they couldn't ignore more annoying than wrong results, and, when judging the relative merits of programming languages, some still seem to equate "the ease of programming" with the ease of making undetected mistakes.”
Edsger W. Dijkstra (1930–2002) first seen 1976 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1976-79) On the foolishness of "natural language programming" (EWD 667)
“Several people have told me that my inability to suffer fools gladly is one of my main weaknesses.”
Edsger W. Dijkstra (1930–2002) first seen 1978 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1978) The pragmatic engineer versus the scientific designer (EWD 690).
“Write a paper promising salvation, make it a 'structured' something or a 'virtual' something, or 'abstract', 'distributed' or 'higher-order' or 'applicative' and you can almost be certain of having started a new cult.”
Edsger W. Dijkstra (1930–2002) first seen 1979 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1979) My hopes of computing science (EWD 709).
“As a result of a long sequence of coincidences I entered the programming profession officially on the first spring morning of 1952, and as far as I have been able to trace, I was the first Dutchman to do so in my country.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“We must be very careful when we give advice to younger people: sometimes they follow it!”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“We must not forget that it is not our [computing scientists'] business to make programs, it is our business to design classes of computations that will display a desired behaviour.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“The major cause [of the software crisis] is that the machines have become several orders of magnitude more powerful! To put it quite bluntly: as long as there were no machines, programming was no problem at all; when we had a few weak computers, programming became a mild problem, and now we have gigantic computers, programming has become an equally gigantic problem. In this sense the electronic industry has not solved a single problem, it has only created them, it has created the problem of using its products.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“FORTRAN's tragic fate has been its wide acceptance, mentally chaining thousands and thousands of programmers to our past mistakes.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“LISP has been jokingly described as "the most intelligent way to misuse a computer". I think that description a great compliment because it transmits the full flavor of liberation: it has assisted a number of our most gifted fellow humans in thinking previously impossible thoughts.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“When FORTRAN has been called an infantile disorder, full PL/1, with its growth characteristics of a dangerous tumor, could turn out to be a fatal disease.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“Using PL/1 must be like flying a plane with 7000 buttons, switches and handles to manipulate in the cockpit.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“If you want more effective programmers, you will discover that they should not waste their time debugging, they should not introduce the bugs to start with.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“Program testing can be a very effective way to show the presence of bugs, but it is hopelessly inadequate for showing their absence.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“The effective exploitation of his powers of abstraction must be regarded as one of the most vital activities of a competent programmer.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“The purpose of abstracting is not to be vague, but to create a new semantic level in which one can be absolutely precise.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“The use of COBOL cripples the mind; its teaching should, therefore, be regarded as a criminal offense.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“APL is a mistake, carried through to perfection. It is the language of the future for the programming techniques of the past: it creates a new generation of coding bums.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“FORTRAN, 'the infantile disorder', by now nearly 20 years old, is hopelessly inadequate for whatever computer application you have in mind today: it is now too clumsy, too risky, and too expensive to use.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“In the good old days physicists repeated each other's experiments, just to be sure. Today they stick to FORTRAN, so that they can share each other's programs, bugs included.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“It is practically impossible to teach good programming to students that have had a prior exposure to BASIC: as potential programmers they are mentally mutilated beyond hope of regeneration.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“Besides a mathematical inclination, an exceptionally good mastery of one's native tongue is the most vital asset of a competent programmer.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“Simplicity is prerequisite for reliability.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“Programming is one of the most difficult branches of applied mathematics; the poorer mathematicians had better remain pure mathematicians.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“We can found no scientific discipline, nor a hearty profession, on the technical mistakes of the Department of Defense and, mainly, one computer manufacturer.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“About the use of language: it is impossible to sharpen a pencil with a blunt axe. It is equally vain to try to do it with ten blunt axes instead.”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“Thank goodness we don't have only serious problems, but ridiculous ones as well.”
Edsger W. Dijkstra (1930–2002) first seen 1982 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1982) "A Letter to My Old Friend Jonathan" (EWD475) p. 101 in
“[Though computer science is a fairly new discipline, it is predominantly based on the Cartesian world view. As Edsgar W. Dijkstra has pointed out] A scientific discipline emerges with the - usually rather slow! - discovery of which aspects can be meaningfully 'studied in isolation for the sake of their own consistency.”
Edsger W. Dijkstra (1930–2002) first seen 1982 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1982) as cited in: Douglas Schuler, Douglas Schuler Jonathan Jacky (1989) Directions and Implications of Advanced Computing, 1987. Vol 1, p. 84.
“How do we convince people that in programming simplicity and clarity —in short: what mathematicians call "elegance"— are not a dispensable luxury, but a crucial matter that decides between success and failure?”
Edsger W. Dijkstra (1930–2002) said by 2002 at the latest wikiquote, CC BY-SA 4.0 source
“I think of the company advertising "Thought Processors" or the college pretending that learning BASIC suffices or at least helps, whereas the teaching of BASIC should be rated as a criminal offence: it mutilates the mind beyond recovery.”
Edsger W. Dijkstra (1930–2002) first seen 1984 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1984) Source: The threats to computing science (EWD898).
“The question of whether Machines Can Think... is about as relevant as the question of whether Submarines Can Swim.”
Edsger W. Dijkstra (1930–2002) first seen 1984 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1984) The threats to computing science (EWD898).
“Simplicity is a great virtue but it requires hard work to achieve it and education to appreciate it. And to make matters worse: complexity sells better.”
Edsger W. Dijkstra (1930–2002) first seen 1984 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1984) On the nature of Computing Science (EWD896).
“Probably I am very naive, but I also think I prefer to remain so, at least for the time being and perhaps for the rest of my life.”
Edsger W. Dijkstra (1930–2002) first seen 1985 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1985) Where is Russell's paradox? (EWD 923A).
“When we had no computers, we had no programming problem either. When we had a few computers, we had a mild programming problem. Confronted with machines a million times as powerful, we are faced with a gigantic programming problem.”
Edsger W. Dijkstra (1930–2002) first seen 1986 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1986) Visuals for BP's Venture Research Conference (EWD 963).
“My point today is that, if we wish to count lines of code, we should not regard them as "lines produced" but as "lines spent": the current conventional wisdom is so foolish as to book that count on the wrong side of the ledger.”
Edsger W. Dijkstra (1930–2002) first seen 1988 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1988) "On the cruelty of really teaching computing science (EWD1036).
“As economics is known as "The Miserable Science", software engineering should be known as "The Doomed Discipline", doomed because it cannot even approach its goal since its goal is self-contradictory. (...) Software engineering has accepted as its charter "How to program if you cannot.”
Edsger W. Dijkstra (1930–2002) first seen 1988 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1988) "On the cruelty of really teaching computing science (EWD1036).
“The problems of the real world are primarily those you are left with when you refuse to apply their effective solutions.”
Edsger W. Dijkstra (1930–2002) first seen 1988 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1988) "On the cruelty of really teaching computing science (EWD1036).
“When I came back from Munich, it was September, and I was Professor of Mathematics at the Eindhoven University of Technology. Later I learned that I had been the Department's third choice, after two numerical analysts had turned the invitation down; the decision to invite me had not been an easy one, on the one hand because I had not really studied mathematics, and on the other hand because of my sandals, my beard and my "arrogance" (whatever that may be).”
Edsger W. Dijkstra (1930–2002) first seen 1166 wikiquote, CC BY-SA 4.0 source
Recorded in: Dijkstra (1993) "From my Life" (EWD 1166).