Theories of Semantics on theWeb - Social Semantics: The Search for Meaning on the Web - page 103

his URI, and the owner has no real responsibility to host any Web representations
at the URI. Since the owner can causally establish a name for a non-Web accessible
thing via simply minting a new URI without hosting any web-page, under the causal
theory of reference the Semantic Web can be treated as having a giant translation
manual mapping URIs directly to referents, where the URIs refer directly to objects
in the world outside of the Web. Realistically, if an agent got a URI like http://
www.example.org/Gustave Eiffel and one wanted to know what the URI referred
to, one could use a service such as whois to look up the owner of the URI, and
then contact the owner of the URI if there was any doubt in the matter. Yet since
obviously such URIs cannot access things outside the Web and contacting the owner
every time a URI is to be used is absurd, what kinds of web-pages, if any, should
this giant Semantic Web dictionary return? If it returns no web-page, how can a
user-agent distinguish a URI for a referent outside the Web from that of a URI for a
web-page? This question is partially answered by Berners-Lee in a solution called
' 303 redirection,' where a distinct URI is given to the thing-in-of-itself, and then
when this URI is accessed by an agent such as a web-browser, a particular Web
mechanism called the 303 Header redirects to the agent to another URI for a
web-page describing the resource, either in RDF or in HTML, or both. However,
this mechanism has been considered difficult to use and understand, “analogous to
requiring the postman dance a jig when delivering an official letter” (Hayes 1977).

4.5 Sense and Reference on the Web

The Semantic Web has still not experienced the tremendous growth of the hypertext
Web, and the primary reason appears to be this impasse at the Identity Crisis.
For the first few years of its existence (2001-2006), in general the arguments
of Hayes prevailed, and the URIs used in RDF graphs did not access any web-
pages. However, in this phase of its existence, the Semantic Web did not progress
beyond yet another little-used knowledge representation language. In the last few
years (2006-2012), the Semantic Web has experienced phenomenal growth under
the term 'Linked Data,' as Berners-Lee's position has had more acceptance and
users have started deploying RDF using actual URIs. This growth is estimated as
billions of RDF triples, including large-scale projects by the biomedical community
and in government data in using the Semantic Web, seems to have implicitly
validated Berners-Lee's direct reference position. Yet that is far from true; what
is apparent from any analysis of the Semantic Web is that there appear to be too
many URIs for some things, while no URIs for other things (Halpin and Lavrenko
2011b). As differing users export their data to the Web in a decentralized manner,
new URIs are always minted, so running the risk of fracturing the Semantic Web
into isolated 'semantic' islands instead of becoming a unified web, as the same
URIs are not re-used. The critical missing element of the Semantic Web is some
mechanism that allows users to come to agreement on URIs and then share and