"entail", "imply", "implicate"

--- We are discussing:

with Kramer (his example):

"the present King" -- he drops the 'present' as otiose

"of France does not like sushi".

--- He has the affirmative, but I'm playing the devil's advocate.

A good passage here -- and short to boot! -- is Grice, WoW: -- so let me quote it:

"If I say that somebody thinks (or believes) that
such-and-such, there is no indication that what he
thinks oor believes is true. Supposing,however, I
take the verb 'discover', and I say 'Somebody
discovered that the rook was leaking'. Here, it
is NOT LOGICALLY POSSIBLE"

and even impolite, I would add...

"to discover that one's roof is leaking
unless one's roof is leaking. On the other hand,
I do not think (THOUGH, PERHAPS THIS IS
DOUBTFUL)"

-- not that he doesn't think it -- the other stuff --

"that so-and-so did NOT discover P also
implies that P is true. I think I CAN
say that some explorer"

Cook -- I cannot read this example without thinking "Cook"

"went off to someplace expecting to
discover that the natives were very
interesting in certain respects, but that
he did NOT discover that because they
were not."

--- and this is the moral to draw then:

"So hwere we have a case where there is
a LOGICAL IMPLICATION on the part
of the affirmative, but not on the part of
its denial. (That looks like a case of
entailment)." (WoW: 270).

I.e.

affirmative: 'logical implication' or 'entailment'
negative: 'implicature'.