The Psychological Foundations of the Grammar 57
Sperber and Wilson (1995: 20) argue that the requirement of mutual or
shared knowledge is untenable, and furthermore that it is unable to describe
‘how contexts are actually selected and used in utterance interpretation’.
They provide the example:
(6) The door’s openand argue that the interlocutors may have mutual or indeed shared know-
ledge of hundreds of doors. But they note that reliance on such knowledge
does nothing to explain how the choice of the actual referent is made. They
propose instead the notion of cognitive environments (ibid. 38–9) which they
argue are made up of manifest facts. They defi ne the terms as following.
A fact is manifest to an individual at a given time if and only if he (sic) is
capable at that time of representing it mentally and accepting its repres-
entation as true or probably true.
A cognitive environment of an individual is a set of facts that are manifest
to him. (sic)They draw a neat analogy between an individual’s cognitive and visual
environments which they defi ne as being made up of all the visual stimuli
manifest to a particular individual. To develop the analogy they propose
between an individual’s cognitive and visual environments, let us imagine
a skilful tennis player. Based on her previous training, experience and
memories and knowledge of the rules of the game she is able to predict
quite accurately where her opponent is likely to return the ball.^9 She does
not need to peer into her opponent’s mind in order to understand her
opponent’s intentions to anticipate the shot. Similarly a communicator
does not need to peer into the intentions of the intended audience before
producing the required linguistic stimuli.
People can alter others’ visual environments even though they do not (and
probably cannot) know the full extent of the others’ original visual environ-
ments. For example, were you to enter a room after twilight and fi nd your
friend sitting in dark shadows, based upon your own visual environment you
could be certain that she could not read a newspaper headline you had just
placed on a table in front of her. To expand her visual environment to include
the newspaper you would simply have to fl ick the light switch. Similarly when
speakers communicate they draw upon their own cognitive environments to
allow them to alter their interlocutors’ cognitive environments.