Halliday & Matthiessen (1999: 428):
Jackendoff views information about the projected world in conceptual terms; hence reality construction is seen as a process taking place within the consciousness of the individual. Our own view, that the projected world is a semantic construction, foregrounds the interpersonal perspective: meaning is construed in collaboration. Meanings are exchanged; and the “projected world” is constantly calibrated against the interpersonal negotiation of meaning. … The semantic system (as part of the linguistic system) is shared; it is part of our social being.