A bagatelle for the left hand

This is a kind of glossary --very incomplete, I am afraid-- of terminology I have learned to suspect. There was a time when it used to disturb me to hear or see the heavy use of a term that was never or rarily employed by myself. But, as the years went by, I discovered that I remained quite happy without those terms in my active vocabulary, and my sense of guilt has disappeared to the extent that their use by others can now make me quite suspicious. (The idea to write such a glossary dates from well before I broke my right arm; hence its low serial number.)


Beware of "the real world". A speaker's appeal to it is always an invitation not to challenge his tacit assumptions. When a speaker refers to the real world, a useful counterploy is pointing out that he only refers to his perception of it. We find it nowadays hyphenated in "real-world problems"; please remember that those are typically the ones we are left with when we have refused to apply their effective solutions.

References to "real programmers" I usually counter by the rhetorical question "Am I a virtual programmer?"

Make it a habit to check whether "real" is used as a euphemism for "education resistant". The "real" in "real numbers" passes this test and is quite respectable (provided you believe in Cantor and Dedekind).


natural versus artificial

It is not only the food industry that employs "natural" as a vague recommendation. (The almonds the airlines serve with the drinks are always "Natural hickory flavoured".) In the worlds of logic and computing we find that same laudatory undertone in "natural deduction" and "natural language (programming)". On closer scrutiny it is a euphemism for something like "appealing to the uneducated".

The adjective is acceptable in the technical term "natural logarithm" and "natural numbers" (provided the latter start at zero).

Equally objectionable is the pejorative usage of "artificial". The nicest examples of such usage was given by the high military expert who declared that "obviously NATO is not interested in artificially simplified languages such as Pascal". Must we conclude that defence prefers naturally complicated languages? (Ada seems to confirm that conclusion.)


My Pocket Oxford Dictionary --which requires a rather large pocket-- defines "intuition: immediate apprehension by the mind without reasoning". If we don't believe in miracles, we seem to have only two possibilities: either the reasoning required is so short and standard that it is hardly worth being recorded or mentioned, or the "immediate apprehension" does not amount to much. In the first case "intuitively clear" means


"obvious", in the second case it probably means no more than the absence of obvious counterexamples. In both cases, mathematical texts "recommended" for their appeal to the reader's intuition should be ignored, for such texts promote non-reasoning instead of better reasoning.

Despite the above, there are still people that believe that intuition is a good thing; there is no point in arguing with them for they prefer to believe in miracles.

views of data

I never talk about (different!) "views of data". Not only can I do without them, but I have even the distinct impression that by talking about them people are more hampered than helped.

Plataanstraat 5
5671 AL Nuenen
The Netherlands
27 January 1982
prof.dr. Edsger W. Dijkstra
Burroughs Research Fellow

Transcriber: Kevin Hely.
Last revised on Thu, 19 Jun 2003.