Full Idea
If you and I think 'I am tired', there is a sense in which we think the same thing, and another sense in which we think different things.
Gist of Idea
If two people think 'I am tired', they think the same thing, and they think different things
Source
François Recanati (Mental Files [2012], 18.1)
Book Reference
Recanati,François: 'Mental Files' [OUP 2012], p.246
A Reaction
This is a very nice simple account of the semantic distinctiveness of indexicals, which obviously requires a 'two-tiered framework'. He cites Kaplan and Perry as background.