Halliday & Matthiessen (1999: 446):
The same view of language as distortion is frequently to be met with when language is contained within a model of communication, where a common motif is that language is a vehicle for lying, or at least for concealing the truth. One might surmise that, if language is defined in communicational terms, as a means of transmitting information — especially if this is combined with a semantics based on considerations of truth — then this is how it is likely to appear.