The document compares the code model and inferential model of communication.
The code model views communication as the application of codes that pair signals with meanings. The inferential model sees communication as recognizing a communicator's intentions through inference, not codes. It requires theory of mind and recursive mindreading rather than just associating signals and meanings.
The key differences are that the inferential model positions meaning as a property of shared cognitive environment rather than stimuli. It views the process as making inferences based on evidence rather than just matching signals to meanings. Under this model, codes are helpful but not necessary for communication.