More thoughts on that Blue Glass

John Black commented on my previous post, providing links to interesting pieces of thoughts. Anatomy of a Reference and Ambiguity and Identity are certainly in the line of what we try to entangle here.
Let's put those pieces together. John's blue glass, physically tagged with its URI is a clear example of the difference between access and naming as explained by Pat Hayes. What is accessed using this http URI is an image of the blue glass, but the URI is intended to name the glass itself. Tagging physically the blue glass with a URI sticker or a bar code is something very close to what Pat calls ostention, but it's not the silver bullet to kill ambiguity.
As John clearly points, when you stick a tag somewhere in the physical world, you still need interpretation to know which part of the world is tagged this way, since the world is not "naturally" divided, things and their limits are always the result of some mental operation of division. So a common interpretation of the tag needs a common understanding of the limits of things, and having a common understanding of classes of things, and which kind of tags you put on which class of things is really useful. This is something well known in geographical maps. On ill-designed maps, names are not printed properly, and it's often unclear what (town, river, mountain ...) is named. In well-designed maps, there are a lot of implicit or explicit disambiguation tricks, such as fonts, colors, position of the name vs the named feature etc. One has to know all that to make sense of the map (actually many people are not able to make sense of a map properly). When you come to the ground, you have similar physical tags indicating towns, rivers, streets and house numbers, and you also need similar knowledge to construe those tags in context : this kind of sticker is for a town, that kind is for a street, and so on. And even so, what is the limit of a town, a street, a valley or a mountain remains basically undecidable.

[2016-06-20] John Black's Kashori archives have moved. The reference articles are now here:


Ambiguity, Ostention and Description

Pat Hayes' In Defence of Ambiguity, presented at IRW 2006, has been on my desktop for weeks, and I take it as the most challenging food for thought currently available about the Semantic Web. If you have not yet read it, you should now.
There is only one point on which I would argue. Pat holds that reference can be made by ostention (gesticulation showing what you are about) or description. All Pat writes thereafter about description being inherently ambiguous, I strongly agree with : disambiguation being a contextual process, the more precise the description, the more ambiguity you get, and so on.
But I would hold that ostention is as ambiguous as description, so that reference is ambiguous in nature whatever the way it's done.
Suppose I am holding a book and ask you : "Have you read this?". The reference to "this" is by ostention, since I seem to hold and show "this". But the "ostentatum" indicated by "this" is actually some copy of some edition of some book. Does "this" refer to this specific copy, which happens to be my own personal copy (maybe annotated in some way), or is the referent the particular edition of which this specific copy is a sample, or is it the abstract entity, the book independent of any physical support, of which what I am currently holding happens to be some physical avatar? Every one of those interpretations is meaningful, and only the context of the conversation might disambiguate. So even with ostention, there is ambiguity left.