Transcript

March 28, 1979

Prof. Dr. Edsger W. Dijkstra

Plataanstraat 5

5671 AL NUENEN

THE NETHERLANDS

Dear Edsger,

I have counted you among my friends for some time now and thought that you counted me among yours; you must tell me whether you still wish me to continue doing so after you read this. For I propose to take on a burden of friendship that I hope will be of some help to you although it is perhaps bitter medicine-if you can swallow it at all. I propose to discuss with you as a friend (although perhaps with some bitterness that comes from my own large ego, whichI shall try to keep in check) the sad impairment of your great abilities and your reputation as a creative thinker that result from your powerful and self-indulgent ego.

It is indeed depressing to anyone who respects your truly exceptional talents to see you of late apparently spending a great deal of time on shallow, negative polemics that contribute almost nothing in the way of real knowledge or deep truths to the subject matter they deal with. Instead of utilizing your major talents in the difficult business of discovering new viewpoints, and new understanding and techniques, you make a spectacle of yourself indulging your minor talent for innuendo and derogation. There are occasions on which it is desirable for a person with an outstanding reputation to devote some effort to pointing ·out the flaws ina significant proposal. But it is fatuous to waste time attacking one so weak that it can be demolished by high school debating tactics that avoid serious consideration of fundamental issues and deal only in hostile innuendoes, unsubstantiated arrogant opinions, and trivial nitpicking.

It seems to me (and to many others, I assure you) that some of your recent polemics are based too much on a need to be at stage center and to thrust your private opinions at the public on the basis that since they are the opinions of Dijkstra they must be right and do not need the careful justification that the opinions of others require. Since it concerns me the most, let me try to trace with you the harmful consequences of hubris that are to be found in EWD692.

First, you have wasted I do not know how much time in writing a five page review about an article that interests you so little that you have barely read it and have thought about it almost not at all . I really would have been pleased had you raised some important issues or criticisms about it; this might have led to an interesting and perhaps useful debate. But since you begin with an ego-driven impulse to attack and “grandstand” rather than understand, your review deals consistently with trivial matters.

For example, had you been concerned with understanding, instead of your waspish remarks about my claim that there are advantages in having a programming language that can also serve as a proof language, you might have begun a significant debate concerning the relative merits of equational theories versus full logical systems.You might have observed that while equational theories provide simpler techniques for answering certain questions, there are many other questions that cannot be phrased in such a theory. There are many further interesting issues of this sort that you might have considered.

Another example of how your animus in the review has driven you to make remarks that are both trivial and not quite fair: in the only other part that even pretends to deal with substantive matters, you make much of the fact that it is easy, if one does the most obvious thing, to implement the matrix multiplication program in an inefficient way. In doing so you leave your readers with the impression that this is something you have discovered that I am unaware of, whereas you read it in my discussion of the program. You fail to observe that, if one does the obvious thing, it is easy to implement the Algol program in an inefficient way also. You also fail to note that it is obviously not so hard to implement the functional program without making the copies you suggest.

Your remark that my claim that my program does not name its arguments is “silly” shows how your arrogance and consequent failure to think carefully leads you to make erroneous and shallow comments. As noted earlier in my article, [ 5.1 (f) and 5.2 (f)], the point of the remark that the matrix program does not name its variables is that it does not require a procedure declaration nor the accompanying object program machinery that replaces formal variables by actual ones. Your suggestion about using “parl” etc in Algol would not eliminate the need for such machinery. (Since this machinery forms one of the principal stumbling blocks to the convenient use of the proof methods you and Hoare have pioneered, it is surprising that you should be so blind to this point.)

This recital is becoming too long, yet there are many further indications of how your ego and/or your instinct to attack, rather than inquire, damage your ability to see clearly and to conduct yourself with the reasonableness and fairness that could be expected of someone in your position. Here are just a few:

1) You distributed your review to your EWD “subscribers” without doing me the courtesy of sending me a copy, although you could well have sent me an advance copy — had you done so, I could have helped you raise the level of debate above the trivial and saved you, I believe from some ridicule. Were you perhaps too embarrassed to send me a copy? I can readily see that you might have been.

2) You dismiss in one sentence the substantive part of the section that claims to make a contribution to proving facts about programs(algebra of programs), an area to which you have made important contributions. Does your ego prevent you from even looking at an alternative approach, from seriously considering its pros and cons? You seem to be unable to find a single worthwhile contribution in the article. Having found nothing of merit, why bother to write a review? Is your conceit so great that you feel that your hasty, ill-considered opinions are so vital to the world that it is worthwhile to spend your time on such a review?

3) You speculate [p1] on the basis, I presume, of my 2.1.3 and 2.2.3that I do not understand the ideas of axiomatic semantics. You were wrong again. And gratuitously offensive.

4) Let me conclude this list with a constant practice of yours, in this as well as in many other reviews, that you should be a ware of,because . although it is a ludicrous matter, it a muses many people mightily at your expense. I refer to your practice of making much of people’s mistakes in their use of English, by out right remarks,by numerous “[sic!]”s and the like. This would merely be unpleasant and result in hurt feelings were it not for the fact that the author of these snide comments himself commits some of the most glorious atrocities to be found in English. The result is indeed humorous,but it is scornful humor and I don’t like to see you making yourself the butt of it. In case you doubt me, let me cite a few examples from EWD692: p2: “The question should be raised what we have achieved.Have we done more than creating a new environment for optimizing compilers?”I believe this might be better phrased “The question should be raised:what have we achieved? Have we done more than create a new … “p3: “ … in order to show how repetitive Backus writes” should be:” … how repetitively Backus writes” Another gem on p3: “ … laboriously belaboring the obvious.” The point is that we all make such trivial errors, even EWD, and private friendly help is more in order than public venom.

In private relationships you have always seemed to be decent,friendly and ready to help your colleagues. But when you go public it appears that your ego goes ape, and you display a number of unpleasant qualities. Perhaps you were unaware of how you then appear to others; I imagine you were. Perhaps no one has taken on the unpleasant task of trying to show you this. Since I would like to continue to regard you as a friend, I am obliged to try; for if you continue to use me as you have on this occasion, it will be difficult for us to have a good relationship. I hope I have not been excessively sharp in my criticism; I really do hope it will have some positive value for you. Had I not had considerable admiration and good feeling toward you to begin with, I assure you I would not have taken the trouble to write this difficult letter.

Part of my feeling toward you is founded on a sense of comrade-ship that comes from the struggle of doing creative work, work that is something exhilarating and often discouraging and painful. One develops a special regard for others who share in this search for truth and endure the many defeats that come before one can isolate a new bit of truth. Until recently I had regarded you as someone dedicated to discovering the deepest truths you could find. Now I am confused, but, as I hope you see, I attribute your recent polemics to the ego factors I have tried to illustrate. For your own sake, it is important to observe that your ego-related emotions have at times corrupted the respect for truth that one finds in your work at its best, that they make you appear instead as merely testy, arrogant and opinionated. One of the crucial battles we all must fight if we are interested in the truth is the battle with our own ego,the primary enemy of objective truth.

What dismayed me about EWD6 92 was its lack of respect for a co-worker, for his dedication, like yours, to finding some useful truths.If you are going to attack, do it well, do it with respect, think it out. Don’t rely on waspish comments and innuendo. Your attack was emotional, not well thought out, trivial.

Perhaps the worst aspect of an emotional attack such as EWD692is that it tends to cut off technical communication. Try to imagine how someone in my position would feel about sending you any comments or papers. I would feel rather foolish about discussing problems, say,about correctness proofs with you, since you have given indications of some animus that prevents you from taking my comments seriously,that compels you to attack them without understanding them. I do hope there is some way this situation can be rectified . This was not the situation at all with the very nice letter you sent in May 1978. It was so completely different in tone from EWD692 that the latter was a surprise.

I do owe you an apology for being so extremely slow in answering,but I believe that you already realize from conversations withJohn Williams in Germany that he and I have devoted a lot of attention to the problem you posed in it. The reason it has taken so long is that we had hoped to find a proof of the equivalence of the two programs that was general, based only on their structure,not on the particular functions used in the structure. We have done this — almost. It turns out that one can transform these programs structurally — ignoring their constituent functions — -to two programs that are almost identical; but the equivalence of the two ultimately depends on the details of the constituent functions.

I have also given a lot of thought to some of your other remarks in your letter, but under the present circumstances am hesitant about discussing them with you. I am not giving up on maintaining our relationship if you wish to continue it, but as you can see I am in need of some clarification. You might be interested to compare your letter, — with its friendly and helpful tone, with your remarks in EWD692: I enclose a copy. The contrast is puzzling: which of the two EWD’s are you?

Well, Edsger, I look forward to hearing your reaction. I do hope that you will recognize that, although I have said some things that you will not enjoy hearing , I have said them in an effort to continue a relationship that I have valued and that would have become impossible otherwise. I hope you will find this letter of some value to you , and that we can straighten these difficulties out.

Sincerely

John Backus

91 Saint Germain Avenue

San Francisco, California 94114

Dijkstra to Backus, 1979–04–05