|Index words: index words are words like “here”, “there”, “now”, “me”, etc. which require a closer determination, so that a sentence which includes them can be determined whether it is true or false. A sentence with index words is therefore context-dependent. Index words are not demonstratives. See also deixis, anaphora, context dependency, indexicality.|
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Index words/Supervenience/Chalmers: Reference based on index words takes place on the basis of both: physical facts and "indexical facts" about localization and conceptual use.
Reductive explanation/perspective/indexicality/problem: how do I explain that I am that particular person? And without tautologies? That the index word is true does not seem to be an objective fact about the world, but about the world as I find it, and that it needs an explanation is something I feel. (See Nagel 1986).
Yet it is no obscure fact why it is true when David Chalmers says "I am David Chalmers".
However, the failure of a reductive explanation for index words has to be distinguished from that in the case of consciousness.
The Conscious Mind Oxford New York 1996
Constructing the World Oxford 2014