- From: Drew McDermott <drew.mcdermott@yale.edu>
- Date: Wed, 13 Jun 2001 09:12:12 -0400 (EDT)
- To: www-rdf-logic@w3.org
[Pat Hayes]
As far as I know, there is no *mathematical* way to distinguish
definitions and assertions.
Correct me if I'm wrong, but don't logic textbook mention the case
where a definition is simply an equality or if-and-only-if? E.g., you
might write (bachelor ?x) <=> (and (male ?x) (not (married ?x))). Now
take a theory involving the term "bachelor," and you can easily
convert it to a theory that doesn't mention the term anywhere. This
two-stage process neatly captures the idea of the definition "not
being allowed to be false." By the time you catch a contradiction,
the definition is nowhere to be seen.
Of course, this won't work for recursive definitions, which may be why
people like Russell didn't trust them. My knowledge of the history of
logic is a bit shaky at this point.
-- Drew McDermott
Received on Wednesday, 13 June 2001 09:12:30 UTC