The document discusses two models of communication:
1) The message model, where the speaker encodes a message and the hearer decodes it. This model has problems with ambiguity, reference, intention, nonliteral meanings, and indirectness.
2) The inferential model, where communication relies on shared presumptions and inferential strategies. This model accounts for literal, nonliteral, and indirect language use through recognition of contextual appropriateness and inferences about the speaker's intention. Successful communication is recognizing the speaker's communicative intention.