[sc34wg3] SAM-issue term-subject-identity

[Ann M Wrightson]

Maybe I should have phrased it better - I have no ontological committment to
more than one subject in my phrase "their subjects are identical" (I did not
say "two subjects are identical" - the use of "two" does carry an
ontological committment to more than one)

I hope that we can figure out SAM-criteria for determining when their
respective subject indicators etc indicate that two topics have the same
subject, without resorting to Fregean analysis. I also hope that we can talk
about the identity (as being the same or not) of subjects without separating
the identity of the subject from the subject - that is one heck of a
philosophical minefield. Besides, I reckon Frege was wrong ... and that the
efforts of a legion of labourers in the field of description logic
demonstrate that quite neatly (what I mean is, that if Frege was right,
description logic would not be so hard - since we patently do not have such
radical computational problems in using everyday language)

Ann W.

-----Original Message-----
From: sc34wg3-admin@isotopicmaps.org
[mailto:sc34wg3-admin@isotopicmaps.org]On Behalf Of Marc de Graauw
Sent: 16 July 2002 15:24
To: sc34wg3@isotopicmaps.org
Subject: Re: [sc34wg3] SAM-issue term-subject-identity


* Ann M Wrightson

| 1. Yes, the term is needed, since it is a "co-ordination point" for the
| various arguments about when topics should be merged - including TNC,
since
| the argument there is:
| two topics having the same name in the same scope, is sufficient evidence
to
| consider their subjects to be identical.
|

I think you do not see my point.

I would say in the case you describe in your last sentence, we have
sufficient
evidence to believe those two topics have one and the same subject. We do
not
believe: the two topics have two subjects which are identical.
So my point is: either two topics have the same (one) subject, or the two
topics
have two non-identical subjects. I have absolutely no problem with defining
when
two topics represent the same subject, on the contrary, I agree this is
essential.

My belief that saying 'two subjects are identical' is wrong is inspired by
Freges conception of identity statements. He says, quite rightly I believe,
identity statements are made between names (or definite descriptions, which
uniquely identify an individual) i.e.:
'The morning star = the evening star'
'George W. Bush = the president of the USA'

What such an identity statement means is: the two names refer to the same
thing
(have the same extension).[1]

Now the case in topic maps is fairly similar. We have subjects and subject
identities. Subject identities are like names: they are (in XTM)
<subjectIdentity> elements with content. Subjects are not like names. They
do
not occur anywhere in a Topic Map, they are what is referred to by the
<subjectIdentity> element. <subjectIdentity> is in a sense a name of a
subject.
If we follow this train of thought, it makes sense to say of two
<subjectIdentity> elements S1 and S2: S1 is identical to S2 (S1 = S2). In
this
case, the represent the same subject. It also makes sense to say: NOT( S1 =
S2),
in which case they represent two different subjects.

| 2. The notion of subject identity should be carefully and explicitly
| defined, since this definition determines a v. important aspect of topic
map
| behaviour - including  the vulnerability of a topic map to rogue added
| information.
|

On further reflection I agree my suggestion to drop the term 'subject
identity'
was a bit silly.

<skipped & agreed>

| 5. Here's my candidate for a sufficient case for considering two subjects
to
| be identical:
|
| Two subjects A & B are identical if (and only if): considering all

I would say: "Two subject identities A and B are identical iff ...",
or: "Two subject identities A and B refer to the same subject iff ...".

Marc

[1] Those who find this interesting and are unfamiliar with it can read
paragraph 1 of my XML2001 paper:  http://www.marcdegraauw.com/whatisis.pdf




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