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Re: Squaring the HTTP-range-14 circle [was Re: Schema.org in RDF ...]

From: Pat Hayes <phayes@ihmc.us>
Date: Thu, 16 Jun 2011 16:38:41 -0500
Cc: Jason Borro <jason@openguid.net>, Linked Data community <public-lod@w3.org>
Message-Id: <A613C02B-03B0-4DF4-B7FF-10866D002C0A@ihmc.us>
To: Danny Ayers <danny.ayers@gmail.com>

On Jun 15, 2011, at 8:27 PM, Danny Ayers wrote:

> On 16 June 2011 02:26, Pat Hayes <phayes@ihmc.us> wrote:
> 
>> If you agree with Danny that a description can be a substitute for the thing it describes, then I am waiting to hear how one of you will re-write classical model theory to accommodate this classical use/mention error. You might want to start by reading Korzybski's 'General Semantics'.
> 
> IANAL, but I have heard of the use/mention thing, quite often. I don't
> honestly know whether classical model theory needs a rewrite, but I'm
> sure it doesn't on the basis of this thread. I also don't know enough
> to know whether it's applicable - from your reaction, I suspect not.
> 
> As a publisher of information on the Web, I'm pretty much free to say
> what I like (cf. Tim's Design Notes). Fish are bicycles. But that
> isn't very useful.
> 
> But if I say Sasha is some kind of weird Collie-German Shepherd cross,
> that has direct relevance to Sasha herself.

True.

> More, the arcs in my
> description between Sasha and her parents

Sasha and her parents are not themselves in your description. I presume you mean, the arcs between the terms you use, in your description, to refer to Sasha and her parents. 

> have direct correspondence
> with the arcs between Sasha and her parents.

Sasha and her parents don't have arcs between them (unless you are indulging in some cruel treatment of animals.) I presume you mean to refer to certain relationships which hold between Sasha and her parents.

In this simple case (explicitly named relationships, explicit referring names) there is a kind of structural correspondence between the description and the reality, indeed. But as soon as you make the descriptive language even slightly more expressive, this breaks down. (Try adding negation or disjunction of even blank nodes.) And as soon as you admit that reality is more complex than any description of it, it breaks down. So its not a very good foundation to build a semantic theory upon. 

> There is information
> common to the reality and the description (at least in human terms).

No. The reality is what it is; the information is held in the description (the one with the arcs and the names in it.) The information is ABOUT Sash and her parents (and the relationship of parenthood and various categories of doggitude, and so forth.) 

> The description may, when you stand back, be very different in its
> nature to the reality,

You betcha.

> but if you wish to make use of the information,
> such common aspects are valuable.

What common aspects? If you mean to refer to the fact that a description with arcs and names can be TRUE OF some aspect of reality, you are talking about classical model-theoretic semantics, which is based on the idea of reference (AKA denotation) at its root; it is the interpretation mapping from names to the things they are interpreted to refer to (eg between "Sasha" and Sasha.) But the truth-in-an-interpretation relationship is not similarity or isomorphism, and it certainly does not warrant identifying the name with the thing named. Quite the contrary, it relies upon keeping this distinction clear. As Korzybski famously said, the map is not the territory.

> We've already established that HTTP
> doesn't deal with any kind of "one true" representation. Data about
> Sasha's parentage isn't Sasha, but it's closer than a non-committal
> 303 or rdfs:seeAlso.

"Closer"? In what metric? I would say it is about as different as anything can get. 

> There's nothing around HTTP that says it can't be
> given the same name, and it's a darn sight more useful than a
> wave-over-there redirect or a random fish/bike association. I can't
> see anything it breaks either.

OF COURSE it breaks things. It might be true to say that Sasha is a Collie-German Shepherd cross, but Sasha's description or web page certainly isn't. It might be true to say that the description is written in RDF, but Sasha isn't. 

Pat

> 
> Cheers,
> Danny.
> 
> 
> 
> 
> 
> 
> 
> -- 
> http://danny.ayers.name
> 

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Received on Thursday, 16 June 2011 21:39:16 UTC

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