URIs and the Myth of Resource Identity "Another way to put it is that the authoritative descriptive information that I publish licenses the use of my URI in certain models. This is analogous to publishing some interfaces for an object in an object oriented system. You can never be sure that I won't (monotonically) publish an additional interface at some point in the future, just as you cannot be sure I won't publish more descriptive information about me..."
"On the other hand, even if it is not possible to completely describe a resource, it may be possible to unambiguously identify that resource, in the sense of conveying what resource it is, as distinct from all other possible resources.
For example, if I provide descriptive information telling you that the URI http://t-d-b.org?http://dbooth.org/2005/dbooth/ identifies all-and-only the actual, living person with email address email@example.com as of 1-Jan-2005, that is sufficient to unambiguously identify me, distinct from all other possible resources."
"The ability to uniquely identify a resource -- in the sense of conveying the distinction between this resource and all other resources -- is important because it enables others to publish additional descriptive information about the resource, beyond what the URI owner provides. The Semantic Web is all about the network effect created by the use of URIs as universal identifiers. When a URI's resource is uniquely identified, it enables "anyone to say anything" about that resource.
"If a URI's resource is not uniquely identified -- if others must rely solely on authoritative descriptive information about that resource -- then those who wish to make statements about it run the risk that they may have guessed wrong about what resource the URI owner was intending to identify. This hampers others' ability to make statements about that resource, thus diminishing the value of that URI. This is analogous to connecting, to the telephone network, a telephone that nobody wants to call: it consumes resources without contributing anything to the network effect."
Via, URIs and the Myth of Resource Identity.
Related to, Why Different Things are the Same and Architecture of the World Wide Web, Volume One.