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Re: homonym URIs (Re: What if an URI also is a URL)

From: John Black <JohnBlack@kashori.com>
Date: Thu, 14 Jun 2007 09:23:15 -0400
Message-ID: <1c8a01c7ae87$2aa0aea0$6601a8c0@KASHORI001>
To: "Ian Davis" <lists@iandavis.com>
Cc: "Pat Hayes" <phayes@ihmc.us>, "Sandro Hawke" <sandro@w3.org>, <semantic-web@w3.org>

Ian Davis wrote:

> On 13/06/2007 14:10, John Black wrote:
>>
>> Please forgive me, Ian, I'm going to highjack this for myself.
>>
> By all means :)
>
> I wrote:
>
>>> Out of interest how do you attach the English word "Venus" to the 
>>> physical body that you are referring to?
>
> To which you part of your reply was:
>
>> When I write the word Venus, I do it expecting you, my readers, to have 
>> had similar experiences to me. I expect you studied the planets in first 
>> grade, have access to WikiPedia, can clearly see the sky, that some 
>> trusted elder spoke the word "Venus" and pointed your attention to a 
>> bright light in the sky, etc., etc. Also, if I know that there may be 
>> confusion, because the word can be ambiguous, I may add to the dance with 
>> a little jig, as in, "I think Venus, the planet, is wonderful." If I have 
>> already established the context, however, I may count on you to 
>> disambiguate it yourself. In a report about the planets of our solar 
>> system, I expect you to infer yourself that I mean Venus to refer to the 
>> planet, not the tennis player.
>
> This is what I expect and it makes its point very well. My question was 
> somewhat rhetorical to test whether I understood the debate adequately. I 
> think I do now.
>
>
>>
>> Restoring some of Pat's remarks, "The only way out of this is to 
>> somewhere appeal to a use of the symbolic names - in this case, the IRIs 
>> or URIrefs - outside the formalism itself, a use that somehow 'anchors' 
>> or 'grounds' them to the real world they are supposed to refer to."
>
> This is the bit I don't understand. I'm not a logician nor a philosopher 
> so I'm applying the little common sense I have to this problem. It seems 
> to me that there is no difference here between the symbol 
> "http://example.com/venus" and the symbol "venus" (being the word I would 
> utter in conversation). Neither can be attached to the physical object 
> that they refer to. However they can both be understood by relating them 
> to other symbols.

This is the discussion I had hoped for, Ian. Thanks for your thoughtful - 
and thought provoking - remarks. I don't know the answers, this is what I am 
currently investigating. Also, I have to make a living, so a full reply may 
take a while (a few days). But just for starters here is a thought, thanks 
partly to some things I read in John Dewey's "Experience and Nature":

Trying to understand symbols only by relating them to other symbols was 
tried and failed. First, before empirical science was perfected, academics 
tried to explain things in terms of symbols. Symbol systems defined symbols 
in terms of more symbols, sometimes producing marvelous edifices but fairly 
useless in practice.  It was revolutionary when early sceintists said you 
had to start with measurements and observations, and proceed by experiment 
to establish the basic layer of symbols, relationships, and laws. Later, 
during the early days of AI, something similar happened. Brilliantly 
conceived systems of automated reasoning were created and built. But here 
too, systems were based primarily on high-level symbols. Symbolic logic, 
symbolic computation, and symbolic reasoning running on powerful high-speed 
computers were expected to produce systems of great generality and power.

But they didn't. Many people, John Searle, for example, now argue that the 
problem is that in the only systems known to be intelligent, humans, symbols 
are at the top of a huge base of primary experience, all the blooming, 
buzzing confusion of being in the world of sites, sounds, tastes, emotions, 
movements, and actions. These human symbols gain their power through their 
connection to this primary experience. For one thing it relates them back to 
the world from which they came. This makes them more effective symbols. The 
poor results of academics and early AI researchers might have been due to 
believing that you could sort of pluck the cherries of symbols off the 
deep-rooted tree of experience and use them as you pleased, in this 
disconnected state. In fact, it was thought that you could gain even more 
power and generality by freeing yourself of the restrictions of human 
experiences. The problem was that these systems proved rigid and blind 
whenever the problems they confront strayed from the narrow tests, 
prototypes, and goals used during their design and creation.

Paradoxically, it is now thought that the flexibility, robustness, and real 
power of symbolic computation, especially in areas requiring common sense, 
are due in fact to this grounding of symbols in experience.

So, to be brief :) I disagree that we communicate about Venus by just 
relating symbols to other symbols.

John Black
www.kashori.com


> In my naive view of human cognition, I imagine that you and I can 
> negotiate a shared meaning of a symbol by relating them to many other 
> symbols to the degree that really only a single thing can be the referent. 
> My conceptual graph of relations between symbols is isomorphic to yours so 
> the thing at the heart of that graph must be the same as yours.
>
> Clearly this is easier when you are able to indicate the referent of a 
> symbol by pointing to it, e.g. an apple on a tree. However in the semantic 
> web we only have a single sense with which to relate things together. It's 
> like sharing knowledge with someone when neither of you can see, taste, 
> feel or move.
>
>
>> What he is calling "...outside the formalism itself...", I am referring 
>> to as shared experiences, following John Dewey, and which Herbert Clark 
>> calls common ground, Kripke calls a name baptism, and Searle refers to as 
>> the background.
>
> OK, this is new stuff for me, but it seems to me that it's like pointing 
> to the apple in my example above.
>
>
>> So the big, big question, IMHO, for the semantic web is this. What can be 
>> done to mimic, in some minimal, but sufficient way, using existing web 
>> technologies, in a way that machines can utilize if possible, the 
>> grounding of URI in something outside the formalism of RDF/OWL/etc.?
>
> Isn't that where humans come in? Your RDF states that a particular URI, 
> when dereferenced using HTTP, provides a depiction of an apple. I try 
> that, see an apple and conclude that I now understand the meaning of your 
> URI (it may take a while if I don't understand your property).
>
> The following metaphor came to me while writing the above about having 
> only a single sense. I wonder if it helps illuminate why I think the 
> semantic _web_ is different to the world of semantics that came before:
>
>
> Imagine you and a stranger can only communicate through the use of 
> coloured pebbles that you may place in various arrangements. Suppose this 
> stranger arranges a crimson pebble between a yellow pebble and a blue one. 
> Next they place another crimson pebble next to the blue one and a white 
> one next to the new crimson one. Then they place a brown pebble next to 
> the blue one and a grey one beside that. Finally they place a green pebble 
> and a black one with yet another crimson pebble between them.
>
> You start to see a pattern forming. Somehow the crimson pebbles link the 
> other pebbles together and you suspect it represents some common 
> relationship. However, since you can only communicate in coloured pebbles 
> you can never relate that to the rest of the world.
>
> Now, suppose you learn that you can turn the pebbles over. You turn the 
> yellow pebble over and discover a picture of a young Elvis painted on it. 
> You turn the white one over and discover a picture of an older Elvis. You 
> turn the blue pebble over and there's nothing on the other side. The same 
> is true for the crimson pebble. When you turn the grey pebble over you see 
> the number 1935 inscribed on it.
>
> Now you turn to the second arrangement of pebbles. Under the green one is 
> a picture of Bill Haley. The crimson one is blank, as is the black one.
>
> Perhaps you might infer that the red pebble somehow denotes "picture", 
> although with this limited evidence there are many other possible 
> explanations. The more arrangements of crimson pebbles touching pebbles 
> with pictures on the back you see, the more confidence you might gain that 
> the crimson pebble denotes "picture". Even more so if you have no 
> contradictory evidence. At some point you may even infer that the blue 
> pebble denotes Elvis Presley.
>
> Turning the pebbles over is grounding it in the real world; in your human 
> experience.
>
> In the Semantic Web the equivilent of turning the pebbles over is 
> dereferencing a URI. For HTTP URIs, we perform a GET. A human can do it to 
> discover what a URI denotes and by looking at lots of these patterns they 
> can gain confidence in their interpretations of the URIs that denote the 
> relationships between these things.
>
>
> That's how I see the Semantic Web.
>
> Ian
>
>
>
>
> 
Received on Thursday, 14 June 2007 13:23:51 UTC

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