Full Idea
Demonstrative uses of an indexical such as 'this' or 'that' should be taken to be anaphoric on an associated demonstration. It is a semantic requirement on the use of the indexical that it be coreferential with the demonstration.
Clarification
'anaphora' refers back to some previous reference
Gist of Idea
I take indexicals such as 'this' and 'that' to be linked to some associated demonstration
Source
Kit Fine (Semantic Relationism [2007], Post 'Indexicals')
Book Reference
Fine,Kit: 'Semantic Relationism' [OUP 2007], p.124
A Reaction
Similarly 'now' must connect to looking at a clock, and 'I' to pointing at some person. The demonstration could be of a verbal event, as much as a physical one.