Looking back at some recent posts, seems that most of the time, identification processes take place in contexts where the type (class, category ...) of the thing to identify has been explicitly or implicitly defined. It's explicitly said in the paper quoted in my yesterday post, and it appears in an ongoing thread on topicmapmail, where Lars Marius Garshol, speaking about Subject Identity Measure, writes:
"Another consideration is that I think types are extremely important. If the names are the same but the types are disjoint (person and place, say) then you can safely ignore the names. You might even want to make the algorithm consider typing topics first, and only afterwards go after the instances."
This is also maybe behind Jack's post "Seeing As..." . You can identify a "real" person only if you see it as a person, and on the other hand you can consider, given the appropriate identification context, any kind of data : a photograph, a phone number, an email address, a handwriting, the sound of a voice, a perfume ... as identifying a person if you see those data as persons, meaning that you have set an identification context where the type of object to identify is "Person".
Those considerations make me wonder about the credibility of URIs, PSIs and other kinds of "universal identifiers", if set outside any processing context, and maybe the minimal processing context should be the type of the thing identified. If http://psi.oasis-open.org/iso/639/#fra is set as a PSI for an instance of the class "Language", would it make any sense to use this identifier to identify a topic, without assuming implicitly that this topic is itself an instance of this same class?