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Philosophy

The Logic of Indexicals and Context-Dependent Truth

Quick fact

In the 1970s, philosopher David Kaplan proposed a formal logic for indexicals that distinguishes between character (the linguistic rule) and content (the proposition expressed). This framework revealed that the sentence 'I am here now' is logically true—true in all contexts—even though the proposition it expresses is often contingent. This solved the puzzle of how indexicals can have a stable meaning yet express varying truth conditions.

Why this is interesting

The sentence 'I am here now' is always true when spoken, yet it seems to say something different depending on who says it, where, and when. How can one sentence have so many meanings while still being a single expression?