Re: knowledge and belief

["Mark E. Shoulson" <shoulson@CS.COLUMBIA.EDU>]

>Date:         Fri, 9 Jan 1998 07:57:39 -0300
>From: "=?iso-8859-1?Q?Jorge_J._Llamb=EDas?=" <jorge@INTERMEDIA.COM.AR>
>
>Yes, but to claim that someone else is convinced of something one
>need not consider it true, while to claim that someone else knows
>something one must. That's the difference that I have been pointing
>out, not the use in the first person.

Insofar as I follow this discussion (which isn't far), I *think* I'm mostly
in agreement with Jorge.  But something occurred to me today; I don't know
if it actually makes any difference or is at all meaningful or profound,
but just something more to kick around...

Let's take Jorge's reading for now (which I rather like), that "X knows Y"
is the same as "X believes Y, and incidentally the I (the speaker) also
believe Y."  (which would make using "know" in first person redundant,
btw).  Now,

John knows the Bob knows that Mary is ill.

is mostly straightforward: Bob believes Mary is ill, John believes that Bob
believes that, and I, the speaker, believe (a) that Bob believes Mary is
ill, (b) that John believes that Bob believes that, and (c) that Mary is,
in fact, ill.  (at least, I *think* that's what it would entail.
Intuitively it would seem it should also entail that John believe that Mary
is ill, but that doesn't seem to follow from where I started).


Now.  It might be helpful to be able to say something like

So far as John is concerned, Bob knows that Mary is ill.

That is, Bob believes Mary is ill, and John believes (a) that Bob believes
she's ill, and (b) that Mary is, in fact, ill.  The speaker's beliefs are
not at issue here, I think.  Sort of projecting the "speaker" implicature
of "knows" onto Bob (a la Lojban {ga'a}?).

Note that all of these examples are in English, not Lojban.  This is not
least because the Lojban arguments are getting confusing.  It's also
because I'm not completely convinced it actually even applies to Lojban, no
matter how you interpret things.

Anyone enjoying playing with this thought?

~mark