‪In "she saw him", it's clear there are two third persons because they're of different genders. In "she saw her", it's clear because otherwise we'd say "she saw herself".

In "she saw her dog" it's not clear. This has always bugged me.

But if we spoke an Algonquian language, we could easily make it clear!

These languages have a "proximate" third person, meaning the closest or most important one, and an "obviative" third person, meaning the farther or less important one. Sometimes the obviative is called the "fourth person".

In other languages, like Russian, we can make it clear a different way: they have, not only reflexive pronouns like "myself, his self, herself, itself", but also a reflexive possessive: sort of like "she saw herself's dog". That obviously obviates the need for the obviative.

Algonquian languages are a family of native American languages including:

Arapahoan
Blackfoot
Cheyenne
Cree–Montagnais–Naskapi
Eastern Algonquian
Menominee
Meskwaki-Sauk-Kickapoo
Miami–Illinois
Ojibwe–Potawatomi
Shawnee

I got pulled into this from trying to understand a bit about Hopi and Navaho before I go back to the Navaho Nation. Which are *not* Algonquian languages. Hopi is an Uto-Aztecan language, and Navaho is Athabascan. But then I realized I'm incredibly ignorant of American language groups.

https://en.wikipedia.org/wiki/Obviative
https://en.wikipedia.org/wiki/Algonquian_languages

@johncarlosbaez In spoken Finnish, all but one of those sentences could be ”it saw it”. The one exception would be ”it saw itself”. Man, woman, dog, chair, doesn’t matter.
@Pauliinalievonen - Neat! So the Finns can be very terse and ambiguous if they want. But what if they don't want? Can they use genders and say "he saw her?"

@johncarlosbaez "He" and "her" are the same word, "hän", mostly used in written Finnish. So to be completely clear you have to use the persons name, or say "the woman" or "the man" or something like that anyway.

I thought of an example, imagine I was telling you about something I saw in the park. That might go something like this: "This morning in the park I saw this woman with a dog, and it, the woman, bought an icecream. Then it gave it to the dog to lick, but it ate the whole thing!

So as the story goes on I would use "it" more often because it's already clear who is doing what.