This is light-hearted contribtion was written for and performed at the May 2000 W3C AC meeting dinner. At the time a debate had been raging at which one of the questions at stake was whether an XML namespace should be considered a web resource.
Up to Design Issues
In his book
Goedel, Escher, Bach, the computer
scientist Douglas Hofstadter ruminates on self-referential
systems. At times, he uses the approach of a Socratic
dialogue between two characters from Xeno's fable,
Achilles and the Tortoise. The conclusion of several
hundred pages of musings around Bach's fugues, Escher's
recusive drawings, and Goedel's theorem are that you can't
try to distinuish wishes from metawishes,
or the whole system breaks down. Without drawing too many
parallels with the recent XML-URI discusssions, we would like
to relate a conversaion between Achilles and the famous
tortoise, recently overheard in a library.
[Achilles and the Tortoise are each strolling in the library. They meet.]
Achilles: Ah, Mr. Tortoise, I thought I might find you in the library
T: And a very nice library it is too, Achilles.
A: Thank you. It was a communal effort. As were the books. There are so many really beautiful books in the library.
T: And now we have dictionaries!
A: Yes, dictionaries are very important to me, Mr.. Tortoise. I want to use them to understand what some of those books mean.
T: Let's not discuss meaning, please Achilles -- you know what happens when we do that! I want to use these dictionaries in order to check that the books are correct.
A: Well, at least we are agreed that dictionaries are a good idea.
[they round a corner]
T: Achilles, what is that?!
A: Why, a dictionary, Mr. T.
T: But it is in the library! I thought when we defined dictionaries we agreed it was "not a goal" to register dictionaries in the library!
A: But surely that doesn't stop me putting one in the library?
T: Irony heaped on Irony! The Library is for books. That you should abuse it so! A dictionary is not a book. It is a metabook.
A: What? Of course it is book!
T: You said that you wanted it have the form of a book so we make them out of paper -- but that doesn't mean the intent was to put it in the library!
A: But this is my section of the library -- it is the section on Library Architecture and I need a dictionary to define the terms used in that field.
T: But you know that people can loose things in a library, and libraries can burn down ... there are so many reasons that dictionaries should not be in the in the library, Achilles!
A: Look at this way, Mr. Tortoise: when I am doing research in the library, I need to be able to look up words, and so I need a dictionary in the library.
T: You have some woolly notion of finding out what books mean, Achilles, but we haven't agreed about that. The meaning of the semantics of "meaning" are not a consensus in current linguistic epistemorthosemantisophologic theory.
A: I don't need to go into that, but I need a place for dictionaries.
T: Oh, we have all been discussing where dictionaries should go. We have plenty of ideas: We have plans for a new vault building down the road much more secure than this library. We have that white tower on the hill we could use too.
T: Besides, in practice, most of us keep a pocket dictionary for each language we use in our briefcases. It isn't as though we need so many dictionaries. Frankly, dictionaries have such different requirements to books I am shocked to see this dictionary in your section of the library! If you don't take it out out, I will bite your heel.
A: But I thought when we designed the library it was so that any sort of book could go in it. That is why we called it the Global Eternal Bibliotech, after all: it is Good for Every Book. I should be able to keep this dictionary in it simply because it is a book.
T: But Achilles, for the last time, a dictionary is not a book!
With apologies & thanks to Douglas Hofstadter for taking us through the fun (and inevitability) of self-referential systems. Thanks to Ian Jacobs for playing Achilles at the dinner.