Why is 'I am here now' always true when uttered but not necessary?

On Kaplan's account its character guarantees truth in any context of utterance, since whoever speaks is the referent of 'I' and is at the place and time of speaking, yet the content expressed could have been false had the speaker been elsewhere, so the sentence is not necessarily true.

Deixis and Indexicality

Deixis is the encoding of contextual coordinates such as speaker, addressee, time, and place into the meaning of expressions like 'I', 'now', and 'here'.

Definition

Deixis is the linguistic encoding of features of the context of utterance; an indexical is an expression whose reference systematically depends on that context.

Scope

This topic covers the categories of deixis (person, spatial, temporal, discourse, and social), the notion of the deictic centre or origo from which deictic terms are computed, and Kaplan's formal treatment of indexicals via the two-tier distinction between character and content. It addresses the difference between gestural and symbolic uses of demonstratives and the way deictic systems vary across languages.

Core questions

What categories of deixis do languages encode?
How is the deictic centre established and shifted?
How do indexicals differ from other referring expressions?
How does Kaplan's character/content distinction explain indexical reference?

Key concepts

deictic centre / origo
person, spatial, temporal deixis
discourse and social deixis
character vs. content
gestural vs. symbolic use
demonstratives

Key theories

Character and content (Kaplan): An indexical has a constant character (a rule from context to content) but a context-varying content; this two-dimensional framework explains why 'I am here now' is true whenever uttered yet not necessarily true.
Categories of deixis: Deixis is organized into person, spatial, temporal, discourse, and social subtypes, each anchored to the deictic centre and grammaticalized differently across languages.

History

Buhler's notion of the deictic field and origo laid the groundwork; Fillmore's lectures and Lyons's and Levinson's treatments systematized the categories of deixis in linguistics. In parallel, Kaplan's 'Demonstratives' (circulated from the 1970s, published 1989) gave a rigorous semantics of indexicals that influenced both philosophy of language and formal semantics.

Debates

Whether demonstrative reference requires an accompanying intention or demonstration: Disagreement over whether the referent of a demonstrative like 'that' is fixed by the speaker's directing intention, by an associated pointing gesture, or by features of the context independent of intention.

Key figures

Stephen Levinson
David Kaplan
Charles Fillmore
Karl Buhler

Seminal works

kaplan1989
levinson1983

Frequently asked questions

Why is 'I am here now' always true when uttered but not necessary?: On Kaplan's account its character guarantees truth in any context of utterance, since whoever speaks is the referent of 'I' and is at the place and time of speaking, yet the content expressed could have been false had the speaker been elsewhere, so the sentence is not necessarily true.