What is the functional or semantic distinction between proximate and obviative person deixis?

Question

What is the functional or semantic distinction between proximate and obviative person deixis? From what I've read ...

"Deixis is reference by means of an expression whose interpretation is relative to the (usually) extralinguistic context of the utterance, such as who is speaking, the time or place of speaking, the gestures of the speaker, or the current location in the discourse."

"Person deixis is deictic reference to the participant role of a referent, such as the speaker, the addressee, and referents which are neither speaker nor addressee." [i.e. 1st, 2nd, & 3rd person--J.G.]

"Third person deixis is deictic reference to a referent(s) not identified as the speaker or addressee."

"Obviative person deixis is third person deixis that distinguishes a less important referent in the present stage of the discourse from a referent that is more important."

"Proximate person deixis is a third person deixis that distinguishes a referent that is more important at the present stage of the discourse from a referent that is less important."

All of the latter definitions are quoted from the SIL Glossary of Linguistic Terms at http://www-01.sil.org/linguistics/GlossaryOflinguisticTerms/index.htm.

Even with all this help from the SIL website, I'm still having trouble understanding the proximate vs. obviative distinction. Could it be that, in certain contexts, the English phrases "the first one" and "the other one" could be functionally analogous to proximate vs. obviative pronouns? Consider this passage, which I made up:

"So these two guys are sitting at a bar, and the first one says something really nasty about the other one's girlfriend, so the other one smacks the first one right in the jaw. So the first one is screaming bloody murder and calls the police so the other one winds up in jail."

Let's stipulate that the topic of our discourse is the guy known as "the first one." If, by some magic, we now add proximate pronouns (like PROX.SG) and obviative pronouns (like OBV.SG) could we paraphrase the passage like this?

"So these two guys are sitting at a bar, and PROX.SG says something really nasty about the OBV.SG's girlfriend, so the OBV.SG smacks PROX.SG right in the jaw. So PROX.SG is screaming bloody murder and calls the police so the OBV.SG winds up in jail."

Answer 1

Here's a description from the (very complete) Wikipedia page on Ojibwe grammar:

Like most Algonquian languages, Ojibwe distinguishes two different kinds of third person, a proximate and an obviative. The proximate is a traditional third person, while the obviative (also frequently called "fourth person") marks a less important third person if more than one third person is taking part in an action.

In other words, Ojibwe uses the obviative to avoid the confusion that could be created by English sentences such as John and Bill were good friends, ever since the day he first saw him (who saw whom?). In Ojibwe, one of the two participants would be marked as proximate (whichever one was deemed more important), and the other marked as obviative.

Note that which NP gets marked proximate or obviative is determined
by the speaker's decision about which NP is more important.

Answer 2

In Bernard Comrie masterpiece "Language universals and linguistic typology" there is a functional explanation to justify the distinction between proximate and obviative in Algonquian languages. In chapter four, discussing about case marking, we can find a hierarchy of animacy referring to Algonquian languages wich is (from the higher to the lower in animacy): second person>first person> third person proximate> third person obviative. The distinction between two different subtypes in third person avoids the possibility to find a transitive sentence where A and P are equal in animacy (A referring to the first argument of a transitive construction where P is the second). In a non-marked transitive construction the normal flow of information implies an A high in animacy and a P low in animacy (roughly, an agent and a patient). That is the reason why a lot of languages feel the need to specify a different pattern, namely a pattern in wich the A is lower in animacy than the P.