Disallow Self-Reference Loops
Jim's claim is false.
What About "anyone can say anything about anything"?
Jim can say that some sentence references itself,
but we know he's lying or mistaken, just as if he'd said
in(Eric, rm308) ∧ ¬ in(Eric, rm(308)).
It's like a listing of books, where some book has a
checksum-invalid ISBN number. Who will recognize that
as an error; what will they do about it? Can you say you have
that book, in RDF?