Relational Theory and the Russell Paradox
Nice find, but I rather think Dijkstra was on the side of "it's not a paradox".
What really surprises me is a guy like Dijkstra hand-writing a document like that in 1985. I haven't hand-written anything of the kind since getting my first word processor in early 1981. In his defence: you can at least read his writing. I make no such claim.
Quote from dandl on July 7, 2022, 12:28 am...
What really surprises me is a guy like Dijkstra hand-writing a document like that in 1985. I haven't hand-written anything of the kind since getting my first word processor in early 1981. ...
Remember what printers were like in 1985?
It was probably broken.
I'm not sure they've really improved, but at least they're cheap enough now that it doesn't matter.
I do. We had a Teletype (10cps), Diablo daisy wheel (30cps), DEC LA30 (30cps), Centronics NLQ dot-matrix (100+ cps) and a Tally matrix comb line printer (100 lpm). We could generate paper at speed and in volume!
I should have mentioned that from 1976 I worked on a project using runoff/troff/etc for system documentation, with a 600 lpm printer available.
I presented a paper at a computer conference in 1981 with computer-generated slides and announced 'the way of the future'. Hand-writing in 1985 was definitely a legacy choice.
Quote from dandl on July 7, 2022, 12:28 amNice find, but I rather think Dijkstra was on the side of "it's not a paradox".
My friend and logic guru Adrian Larner was of the opinion that Russell's paradox was not a paradox. Sorry that forming an opinion on this matter is above my pay grade.
Hugh
Quote from dandl on July 7, 2022, 12:28 amNice find, but I rather think Dijkstra was on the side of "it's not a paradox".
That's what he said. But my own point was of course about even Dijkstra apparently not being aware of the distinction (subtle or not) (between Barber's and Russell's) that you guys have pointed out to me.
Quote from Hugh on July 7, 2022, 2:25 pmQuote from dandl on July 7, 2022, 12:28 amNice find, but I rather think Dijkstra was on the side of "it's not a paradox".
My friend and logic guru Adrian Larner was of the opinion that Russell's paradox was not a paradox. Sorry that forming an opinion on this matter is above my pay grade.
Hugh
Requires extreme agreement on the precise meaning of the term "paradox". Russell's points out that there are situations where natural language allows us to formulate "definitions" that are demonstrably 100% nonsensical. Barber's points out that there are problems that are so constrained that there are no solutions. SQRT(2) in the set of the rationals for Dijkstra, an actually existing -and unique- barber in Barber's.
Quote from Erwin on July 7, 2022, 9:57 pm
Requires extreme agreement on the precise meaning of the term "paradox".
Writing that down inevitably made me decide to inspect my defamated "dead trees" for "paradox". 2 explanations given :
(1) "A statement, doctrine or expression seemingly absurd or contradictory to common notions or to what would naturally be believed, but in fact really true"
(2) "A statement essentially absurd and false"
Contrast "in fact really true" with "essentially absurd and false" ... Dictionaries are not written down by logicians ...
Quote from dandl on July 7, 2022, 12:28 amWhat really surprises me is a guy like Dijkstra hand-writing a document like that in 1985.
Hugh hand-wrote the first draft of TTM (1993?). Not for publication, but perfectly readable -- even after faxing to Chris. And that used to be available somewhere online. Can I find it now?
Quote from Erwin on July 7, 2022, 11:01 pmContrast "in fact really true" with "essentially absurd and false" ... Dictionaries are not written down by logicians ...
I think you'll find the problem is with the language -- or rather those who use it. Lexicographers ('a harmless drudge' [Samuel Johnson) just try to keep up.
See the history of 'oxymoron' -- which used to make a subtle and useful distinction.
Quote from AntC on July 7, 2022, 11:10 pmQuote from dandl on July 7, 2022, 12:28 amWhat really surprises me is a guy like Dijkstra hand-writing a document like that in 1985.
Hugh hand-wrote the first draft of TTM (1993?). Not for publication, but perfectly readable -- even after faxing to Chris. And that used to be available somewhere online. Can I find it now?
It's at the TTM website but a bit hard to find in the Documents section: https://www.dcs.warwick.ac.uk/~hugh/TTM/Original-TTM.pdf
Hugh