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Re: [XRI] Cooler XRI

From: Pat Hayes <phayes@ihmc.us>
Date: Fri, 24 Oct 2008 12:10:27 -0500
Cc: www-tag@w3.org
Message-Id: <C6F1569F-EE07-43E1-9C05-7C96710DA74E@ihmc.us>
To: John Bradley <jbradley@wingaa.com>

On Oct 24, 2008, at 6:54 AM, John Bradley wrote:

> We all now understand that:
> 	* If an "http" resource responds to a GET request with a 2xx  
> response, then the resource identified by that URI is an information  
> resource;
> 	* If an "http" resource responds to a GET request with a 303 (See  
> Other) response, then the resource identified by that URI could be  
> any resource;
> 	* If an "http" resource responds to a GET request with a 4xx  
> (error) response, then the nature of the resource is unknown.
> Givin this understanding the "Cool URI" document shows us how to  
> construct URI for "real-world objects or things".
> As it happens every XRI is also about a "thing".  We have attempted  
> to come up with better language than "thing".
> I quite like the description used by Stuart Williams of "Platonic  
> ideal" in that when I the XRI =jbradley to refer to me I am not  
> literally refering to me but to an ideal of me that can be descibed  
> by meta-data in the same way that a mathmatician describes a circle  
> via a formula.
> Both myself and any phisical circle are crude appoximations of the  
> ideal.

I would beg you to reconsider this idea. You have just stepped into a  
philosophical trench so deep that only a few specialized submersibles  
can plumb its depths, and survival without specialized aids is  
impossible. Unless you are prepared to deal with the elaborate and  
expensive equipment needed (a graduate degree and an established  
publication record in philosophical metaphysics is an absolute  
minimum) I would strongly urge you to stick to the innocuous  
terminology of "thing". This is not language that needs to be  
improved: its very banality is its power, as what is wanted at this  
point is a term for something that can be, literally, anything. (The  
philosophical word "entity" would have more resonance, but it has  
already been co-opted by XML for a completely different purpose.) All  
that actually matters for Web architectural discussions, in any case,  
is that there are some, er, things that cannot be sent over a byte  
stream, and that some names (URIs, XRIs, whatever) are required to  
denote such things. Further philosophical stipulation about the nature  
of these things is a topic that belongs to philosophy rather than to  
Web science. And to repeat my appeal, please, please do not engage in  
philosophy unless you are seriously prepared for the resulting  
debates. It is not a game for amateurs to play.

Allow me to point out some of the issues that immediately arise, but  
would not have done if you had not tried to invoke the ghost of Plato.

> Givin that the XRI =jbradley names the PI(Platonic ideal) me how do  
> I use that as a URI?
> I can use the proposed sub scheme for a http: XRI and put the  
> relative XRI on a base http: URI:
> http://xri.net/=jbradley
> Now if this URI returns a 303 and link header information about  
> where to retreve meta data about =jbradley and perhaps alternate  
> resources relating to =jbradley based on content negotiation it is  
> by the W3C's definition  a cool URI.

True, but it refers to a Platonic Ideal. I, personally, would have no  
idea how to even begin composing metadata about a Platonic Ideal of a  
particular person. What is there to say about such a thing? One could  
not possibly use this in FOAF, for example, or with any properties  
from Dublin Core, since Ideals don't have friends or engage in  

> The cooler part is that we now have the XRI shared semantics that  
> can be applied to any XRI subsceme URI to describe =jbradley.

Evidently, your Ideal, which this XRI/URI apparently describes, is not  
you, since you live in the physical world and it does not. So now we  
have (at least) two John Bradleys to content with: the Ideal one,  
referred to by an XRI/URI, and the actual one which another URI might  
denote, protected by 303 redirects. I could describe the class of  
these two things using owl:oneOf and it would have a cardinality of  
two. Maybe you want this to happen, though I cannot see any purpose  
for it. It means for example that listing the XRI-Ideal-you as being  
in a class of Wingaa employees would be a category error.

You could try writing a special OWL ontology for handling the Ideal-to- 
real-thing relationships. Some questions arise immediately. Can a  
thing have more than one Ideal? Can an Ideal be the Ideal of more than  
one thing? In both cases, there are good arguments both ways, some of  
them venerable. I guess it would be up to a special philosophical XRI  
working group to decide such questions (and there are of course many  
more of them: what kinds of properties can be attributed to an  
Ideal?), but until they are resolved, XRIs will not be usable along  
with URIs to talk about real-world entities.

> This is achieved through a mechanism simmilar to the one that the  
> W3C recommends near the end of "Cool URI".  They cite D2R Server as  
> an example of using SPARQL and 303 redirects to serve RDF documents  
> about "Platonic ideals".

I don't see anything in there about Platonic Ideals, with or without  
scare quotes. BTW, using scare quotes in philosophy is never done. It  
is an open declaration that you know you don't know what you are  
talking about.

Pat Hayes

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Received on Friday, 24 October 2008 17:11:09 UTC

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