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Re: exploring ambiguity via the "something-which-has" URI scheme

From: pat hayes <phayes@ai.uwf.edu>
Date: Mon, 5 May 2003 17:54:26 -0500
Message-Id: <p05210647badc85515220@[10.0.100.12]>
To: Sandro Hawke <sandro@w3.org>
Cc: uri@w3.org, GK@ninebynine.org, Patrick.Stickler@nokia.com, phayes@ai.uwf.edu

[CCing uri list to put my objection on record. - Pat Hayes]

[Sandro, to Patrick:]

<snip>

>One the second point: Consider the noun phrase "a red thing" in "I am
>holding a red thing in my hand."  That noun phrase could denotes any
>of a huge variety of things, but I'm using it to refer to a very
>specific physical object.  URIs always refer to a specific thing,
>even when no one happens to know anything about that thing.

You just said, they refer to a specific thing even when they do not 
refer to a single thing.

What do you think it means to say that a name refers to a specific 
thing but nobody knows what that specific thing is?  It seems to 
presume that whether or not a name refers to a particular thing is a 
matter of objective fact, like something that could be measured by a 
reference-detector, or something.  But this is obviously a fantasy. 
It is is like saying that URIs have souls.

>  > I think that it is (or should be) a fundamental presumption that,
>>  within the scope of the S/Web, a given URI consistently denotes
>>  a single thing.
>
>Agreed.  I think Graham and Pat and you and I are in violent agreement
>on this on this list.

No, Pat is violently NOT in agreement with this, nor with what you 
said just above, that URIs always refer to a specific but maybe 
unknown thing.  Both of these assertions seem to me to be utterly 
crazy (science-fantasy crazy, Wizard-of-Earthsea crazy) if taken at 
face value, to be incomprehensible if not taken at face value, and to 
be highly misleading either way; and completely unnecessary to even 
attempt to say, in any case. Even if it were somehow magically true, 
nothing would depend on it being true or would break if it were false 
(which is almost certainly is.).

>But there are some tricky edge cases, which is what I am trying to
>flesh out.  In particular, while agents may act as if a URI had one
>true interpretation, they are only acting: we cannot, in general,
>communicate interpretations.  At best, we can arbitrarily constraint
>interpretations; that seems to be good enough for both humans and
>machines.

Right. What makes you think that denotations are any different? 
Particularly when denotations are PART of interpretations.

>  > So if you tried to define a URI scheme that could
>>  intentionally be used to provide for overloading of denotation,
>>  I would consider that to be in conflict with the fundamental
>>  S/Web architecture.
>
>I think it would also be in fundamental conflict with web
>architecture, but ... I'm not sure how to phrase it for 2396bis.  My
>last attempt [2] was ignored by everyone.  :-)
>
>Here's another attempt, changing the basic definition of a URI.
>Again, this goes somewhere near the beginning; exact glue can wait.
>
>    Each URI is a string which conforms to URI syntax and which names
>    something.  The naming relationship gives the URI its primary
>    utility, allowing it to be transmitted in the place of something
>    else.

This is a cargo-cult theory of naming and reference, it's the 
primitive folk theory of names that lies behind sympathetic magic. 
Names *refer*, they don't stand in place of. You don't use names as 
surrogates for what they name. If I want to hurt someone, I don't 
write his name on a wall and punch the wall, or baptise a doll with 
his name and stick needles into it.

There is no 'naming relationship' of the kind you describe. What 
relationship is there between my name and me? My name - which. like 
all names, is just a string of characters, after all, with no magical 
properties - also names (at least) a folk/rock bandleader, a 
film-maker, a Texas civic leader, several Irish farmers, an owner of 
an island in Lake Erie and rather old body-builder. The reason we 
have things like social security numbers is as an attempt to come up 
with some kind of one-to-one naming system at least for citizens of 
one country and its imperfect even at doing that.  But resources can 
be anything, not just citizens. So we would need a SS numbering 
system for *everything*. Even imaginary things, grains of sand, 
tomato seeds, and so on.  *Everything*.  Crazy, right? And completely 
unnecessary. Only someone in the grip of an ideology would even 
consider such an idea.

>  There is no restriction on what kind of thing (real,
>    imaginary, physical, conceptual, ...) can be named by a URI, but
>    all such things are called "resources". 
>
>    For a URI to be used effectively, the parties using it in
>    communication often need to share a notion of which resource it
>    names

Demonstrably false, even for human discourse.

>, but this commonality of knowledge does not need to be
>    complete to be effective.

Oho, now there seems to be a crucial qualification creeping in here. 
What exactly counts as an *incomplete* commonality? Is no commonality 
at all just *very* incomplete? If you make this precise I bet you 
will re-invent model theory.  And why, and how, does an incomplete 
commonality define a *unique* referent, in general?

>In particular, human parties will tend to
>    associate considerable real-world knowledge with the named
>    resource, while software agents will simply maintain the facts
>    about it suitable to their purpose.  In many cases there will be
>    some ambiguity in communication using URIs because of incomplete
>    sharing of knowledge about what is named by each URI, but this
>    ambiguity can often be reduced as far as necessary.

But why does it need to be reduced? For some purposes, communication 
is actually improved by allowing some latitude in reference, in fact. 
To insist on getting all referents clearly identified is a kind of 
pedanticism in communication which we all know can be destructive 
rather than helpful. Like two people arguing about exactly where the 
boundaries of Paris are in order to determine whether or not they 
agree about the proposition "I love Paris".  Now, of course, if you 
have to lay a sewer and get permission from some office to dig a 
ditch, maybe the exact edges of the thing called "Paris" are more 
significant.  It all depends on what you want to DO with the 
information, not about what it REALLY refers to, whatever that is 
supposed to mean.

>    [ maybe say something about renaming and about indexical URIs like
>    my.example.com?  something about GoodURIs having a long-term
>    consensus of meanings.... ]
>
>    In addition to serving as a name, each URIs can also serve as a
>    message, conveying information about the named resource.  The
>    language of the message is identified by the URI's scheme part, and
>    to use the information encoded into the URI, an agent must
>    recognize the scheme name and understand the corresponding
>    language.  A common case is for the URI text to convey the network
>    address of a server which can communicate authoritatively about the
>    resource.

This last point I agree is worth saying, though wouldn't it be better 
to say that the URI identifies the message, rather than serving as 
one? Seems to me that URIs are (usually) indeed 'bound to' one thing, 
in a sense, but all the confusion comes from thinking of this 'bound 
to' relationship as being a kind of  naming or reference. What they 
are bound to is usually a *source of information about* what they 
denote. If the information provided by that source, using appropriate 
Web conventions, is enough to identify a single thing, then maybe in 
those cases it might make sense to talk about the URI being bound to 
(in a different sense of "bound to") the thing that is thus uniquely 
identified (in some appropriate sense). The 'namespace' examples 
might be like that, for example, if we allow the W3C to have 
unique-naming powers over its own abstractions, which seems fair 
enough: if you ping those URIs, you get a W3C web page which tells 
you, using W3C linguistic conventions, what the namespace is.  But 
those 'unique' cases are relatively rare; they depend on external 
social conventions; and they are not in any way required in order for 
the SW (or indeed the non-S Web) to operate properly. The stuff found 
on most browsable web pages is not 'about' any one single thing, and 
there's absolutely nothing in either the technology or the sociology 
of the Web that requires it to be.

Pat
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Received on Monday, 5 May 2003 18:54:31 GMT

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