Newsgroups: bit.listserv.csg-l
Date:         Tue, 17 Nov 1992 15:14:20 EST
From:         "Bruce E. Nevin" <bnevin@CCB.BBN.COM>
Subject:      propositions

[From: Bruce Nevin (Tue 921117 12:46:29)]

(Martin Taylor 921113 16:00) --

OK, so "propositions" are in this usage (you, Bill C.) not language
entities but nonverbal perceptions.  For me, "propositions" are
sentences in a language, usually a formal "language" related to natural
language (it is claimed) by some machinery of formal semantics.  This is
I think standard usage in philosophy and linguistics, but correct me if
I'm wrong.  I'll try to keep the two usages distinct.

As I recall, this started with my suggestion to Bill C. that the Hamming
distance is not to be measured between sets of propositions (sentences
in a formal "language") but between sets of perceptions.  For
computational purposes, these perceptions must be represented as
propositions (=sentences).  However, it is important to bear in mind
that they are not propositions, conceived typically as hanging out there
in neutral-observer-space between the communicators.  Instead, they are
private perceptions within each communicator, about which they may
severally formulate and utter propositions in some (natural or formal)
language.  They may come to agreement about the propositions
(=sentences) at Pask's level 1 of repetition or level 2 of paraphrase.
Agreement level 1 could be reached by a record/playback device.  Level 2
agreement could be reached by a computer equipped with a natural
language parser and capable of paraphrase.  However, level 3 agreement
cannot be reached by anything other than a control system controlling
perceptions that correspond to those of the originator.  Well, maybe
some simulacrum could be reached with an elaborate enough knowledge base
associated with the parser/paraphraser used for level 2, but I doubt
this arrangement could pass the Turing test for long.

Pask's level 3 feedback gives to the Originator O (in your words)

>>                                           an iron-clad guarantee that
>>R had received what O intended to send.  Such an agreement seems to me
>>to be more than a simple agreement about a simple perception, and far
>>more than an agreement like "yes, we employed that string of words."'

At level 3, R refers to his or her perceptions associated
privately with O's message, and talks about those perceptions without
either repeating or paraphrasing what O had said.  Closing the loop, O
finds that this description accords with what O might have said about
O's private perceptions, and tells R so.

You said that the "propositions" are instances of the "primal message"
in O's communication to R.  But (in your words) "the Primal Message is a
the reference state for the Originator's (O's) belief about the
Recipient's (R's) belief." In other words, the "primal message" is a
remembered or imagined perception.  A belief is not a proposition
(=sentence), though sentences may represent or express a belief.

An aside: a belief (it seems to me) is a perception that you assume
(perceive) to be a true reflection of Boss Reality.  But that is not
sufficient.  By that definition, when I look out my window and perceive
that it is snowing I would have to call that perception a belief.  Only
a PCT afficionado would find no error there ;-)  For most folks, a
belief is an imagined perception that we perceive as veridical but
unsupported by direct evidence.  But most folks (that is, most of us
most of the time) identify beliefs with statements of belief, just as
they (we) confuse perceptions in general with descriptions of them.
Must have something to do with how words evoke imagined perceptions and
perceptions evoke words--however that happens.  But I wander.

        Bruce
        bn@bbn.com
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