Edsger W. Dijkstra Quotes

Computer Science is no more about computers than astronomy is about telescopes

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.

"I mean, if 10 years from now, when you are doing something quick and dirty, you suddenly visualize that I am looking over your shoulders and say to yourself "Dijkstra would not have liked this", well, that would be enough immortality for me."

The question of whether Machines Can Think... is about as relevant as the question of whether Submarines Can Swim.

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?

The question of whether a computer can think is no more interesting than the question of whether a submarine can swim.

It is not only the violin that shapes the violinist, we are all shaped by the tools we train ourselves to use, and in this respect programming languages have a devious influence: they shape our thinking habits.

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?

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.

Lisp has jokingly been called “the most intelligent way to misuse a computer”. I think that description is 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.

Testing shows the presence, not the absence of bugs

We can found no scientific discipline, nor a hearty profession, on the technical mistakes of the Department of Defense and, mainly, one computer manufacturer.

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.

In the wake of the Cultural Revolution and now of the recession I observe a mounting pressure to co-operate and to promote "teamwork". For its anti-individualistic streak, such a drive is of course highly suspect; some people may not be so sensitive to it, but having seen the Hitlerjugend in action suffices for the rest of your life to be very wary of "team spirit". Very.

Elegance is not a dispensable luxury but a quality that decides between success and failure.