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RE: [lojban] RE:not only
- To: <lojban@yahoogroups.com>
- Subject: RE: [lojban] RE:not only
- From: "And Rosta" <a.rosta@dtn.ntl.com>
- Date: Fri, 20 Apr 2001 16:47:20 +0100
- Importance: Normal
- In-reply-to: <4.3.2.7.2.20010419182524.00bf3eb0@127.0.0.1>
I have to say, contra pc but with apparently everyone else, I judge
"In the animal kingdom, only spiders have exactly nine legs" to
be false. (OK, I admit I find it hard to distinguish falsity from
true-but-implying-false-with-maximal-strength, but the way to
settle this would be to find a true example that doesn't imply
the contrary, and noone's come up with such an example.)
Hence "Only S are P" cannot be an exact equivalent of "All P are S",
contrary to the position pc takes and I took for many years until
now.
Instead, "Only S are P" should be treated as equivalent to
A. "S are P and nothing but S are P"
or
B. "S are P and all P are S".
OTOH, in practise, "All P are S" would serve perfectly well to
communicate "Only S are P", so it seems to me that the logically
fastidious among us could happily make do with simply abjuring
po'o.
--And.