Re: Propositions

From: HARNAD Stevan (harnad@cogsci.soton.ac.uk)
Date: Tue Jun 04 1996 - 09:40:06 BST


> From: "Patel, Suzie" <RMSP195@psy.soton.ac.uk>
> Date: Thu, 23 May 1996 18:09:00 GMT
>
> A proposition is the abstract meaning that is expressed by a word
> within a sentance.

No, a proposition is a statement that something is the case (such as:
"this is a pipe," or "the cat is on the mat" or "2 + 2 = 4"). It is
called a proposition because it PROPOSES that something is the case,
that something is true. Hence propositions can be true or false.

The proposition itself is not the string of symbols that can be
interpreted as expressing it; those are just meaningless squiggles and
squoggles. The proposition is the meaningful statement that the symbols
can be interpreted as expressing. So the symbol string "this is a pipe"
can be interpreted as meaning that this is a pipe.

> Example; Two people called "A" and "B" were having a chat. "A"
> told "B" about a piece of string that "B" had not seen., he said "
> the sring was long", and because "B" had not seen the piece of string
> he believed what "A" had told him.

This is an example of people exchanging information in the form of
symbols that can be interpreted as propositions about what is and is not
true.

> The "long" part of the sentance would be known as the proposition
> word.

No, "long" is the predicate, and "string" is the subject, and
propositions often take the form of subject and predicate
(this/not-pipe, cat/on-mat, (2+2)/4, etc.).

> This would be so as "A" was proposing that the string was long.

A was saying of the string that it is long. Yes, "that it is long" can
also be thought of as the proposition, but without the "it," and knowing
what "it" is (the string), it would just be a predicate: "is long": A
dangling predicate is not a proposition. (What was your source for this
example? It's best to read Kosslyn on Pylyshyn on propositions vs.
images.

> So the way in which a person descibes a item, situation, occurance ,
> or anything for that matter is proposing it, in a way in which they see
> it to be themselves " in the eye of the beholder ". This may only be
> true if the talking to someone whom did not see the item for
> themselves. This type of proposition word's are universaly used in
> all different languages.

Kid-sib would not have been able to understand the preceding paragraph.
Relate propositions to images, computation, etc.



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