Opiniatrety

Do Knowledge Ascriptions Presuppose Truth?

That's positive and negative ascriptions, otherwise the question would be easy. I sometimes go around arguing that the most common use of "S knows that p" or "S doesn't know that p" is in a context in which the truth of p is presupposed, and the only question at issue is whether S believes that p.

"S doesn't know that p" obviously doesn't presuppose that p in the way that "The present King of France is bald" presupposes that there is a present King of France (if it does; I don't want to get into this). There are lots and lots of contexts in which "S doesn't know that p" can be sensibly uttered when p is false. But I think that in many contexts "S doesn't know that p" does implicate that p; whether this is conversational or conventional, I'm not sure.

I'm thinking about this because of this line from Jordan Barab's post on the National Association of Manufacturers' callousness and deception on the lead paint issue:

No matter, the last time one nationally-known paint company had any lead in their paint was 1938, a fact little-known to the public and oft-ignored by the trial bar.

It's little know[n] because it's not true....75 percent of houses and apartments built before 1978 in the United States still contain lead paint.

"It's little known because it's not true" strikes me as an unusual though effective way of rebutting the NAM claim. Ordinarily "It's little known" suggests that it is true, even though the vast majority of claims that are not widely known are false (since all false claims are not widely known). So Barab points out that this is one of those claims that's not known because it's false. [UPDATE: Of course the NAM's use of "fact" does entail that it's true--thanks to P.D. in comments. I guess I'll have to ask you to pretend that they said "It's little known that..."]

Now in this case there's another way to the implicature. "It's little known" implicates that at least a few people do know it. (Perhaps it even entails it.) That in turn entails that it is true. That Barab can reiterate that "It's little known" while saying it isn't true suggests that:

"It's little known" doesn't entail that someone knows it, and Barab cancels the implicature;
Barab has switched to a sense of "know" in which "know" means "believe" (or some other non-factive sense);
Barab is using "it's little known" sarcastically.

Since the last is a possibility, it's probably wrong to draw any firm conclusions about the use of "know" here. But the oddity of what Barab says at least reminds me of the fact that saying "S doesn't know that P" usually suggests P.

(That wasn't a very impressive ending, was it? via Drum.)

Posted by Matt Weiner at November 9, 2005 12:52 PM