Halliday examines the clause from three angles: as the representation
of a fact, as a communicative event between speaker and hearer and as a
communication. He sees in these three simultaneously existing aspects of
clause-meaning the impress of three linguistic meta-functions: the ideational,
the interpersonal and the textual function (cf., among others, Halliday
(1970, 1973)). The third of these aspects is of significance for the discussion
in this sub-section, i.e. the clause described as the communication of
a speaker to a hearer. English grammar offers three possibilities:
1. The description of the information structure of the clause
as given and new. Instead of the mathematical concept of
"information" which has been developed in cybernetics, Halliday sees it
as the interplay between given and new in the information unit, which can
coincide with the clause.
"Information... is a process of interaction between what
is already known or predictable and what is new or unpredictable. This
is different from the mathematical concept of information, which is the
measure of unpredictability. It is the interplay of new and not new that
generates information in the linguistic sense. Hence the information unit
is a structure made up of two functions, the New and the Given." (Halliday
1985: 274 f)
Regarding the clause as a communication therefore means describing the
distribution of given and new information, which is characterised by intonational
features. Phonologically speaking, an information unit consists of a sequence
of tone groups, these in turn being composed of smaller units, the
tone feet. The tone feet, which consist of one or more syllables,
represent not only phonological constituents, but also units of information.
Tone feet carrying the main accent in the clause mark the end of the new
element, which, as the focus of information with normal intonation, is
placed on the last lexical item. The difference can be illustrated with
the help of the two sentences below. In the first, the direct object is
composed of a lexical item (= wallet), and in the second,
of a pronominal element (= it). Accordingly, the main accent
(shown in the examples by the relevant word being underlined) is in a different
place.
(67) // John / lost / his wallet //
(68) // John / lost it //
The fact that the main accent falls on the last lexical item in the
clause (with normal intonation) means that the given element precedes the
new element in the information structure. Describing the clause as an information
unit with given and new, and sequencing these two parts according to the
phonological criterion of tonic prominence, leaves open the question
of what is understood by 'given' and 'new'. Many attempts have been made
to define these two terms, sometimes only adding to the confusion. They
have been linked to whether or not a discourse topic has been mentioned
before in the text, to the givenness or non-givenness of referents in the
situation, and to the question of whether some shared knowledge is available
or not. Halliday concedes that these things can be significant for a definition
of given and new, but says that they play only a secondary role compared
with the significance of the speaker. Halliday defines 'given' as the information
the speaker presents to the hearer as recoverable; 'new' is the information
which is presented by him to the hearer as non-recoverable.
The idea that the speaker decides what should be given or new is formulated
in various ways by Halliday, one of which is quoted below:
"The constituent specified as new is that which the speaker
marks out for interpretation as non-recoverable information, either cumulative
to or contrastive with what has preceded the given is offered as recoverable
anaphorically or situationally. These are options on the part of the speaker,
not determined by the textual or situational environment; what is new is
in the last resort what the speaker chooses to present as new, and predictions
from the discourse have only a high probability of being fulfilled. Nevertheless
the structure of the information unit does contribute in large measure
to the organization of discourse, by providing a framework within which
these options are exercised." (Halliday 1967: 211)
2. The theme-rheme structure of the sentence. For Halliday, the theme
is the starting point of the communication chosen by the speaker,
whilst the rheme is the remaining part which develops the
theme. In English, the theme-rheme structure is conveyed by word order.
The part of the communication chosen by the speaker as the theme opens
the sentence as the first constituent:
"... whatever is chosen as the Theme is put first." (Halliday
1985: 38)
"... the Theme can be identified as that element which
comes in first position in the clause." (Halliday 1985: 39)
(See Halliday 1985: chapter 3.5 for further possible positional realizations
of theme in English.)
The theme-rheme organization and the information structure of a sentence
are semantically interconnected. In the normal case, the speaker chooses
the theme from what is given in a communication, i.e. from the parts of
a communication which the hearer can reconstruct and which are accessible
in his store of knowledge. The speaker also places the emphasis, or information
focus, of his communication on the part reserved for the communicationally-new,
i.e. positionally for the rheme.
"There is a close semantic relationship between information
structure and thematic structure... Other things being equal, a speaker
will choose the Theme from within what is Given and locate the focus, the
climax of the New, somewhere within the Rheme." (Halliday 1985: 278)
3. The system of identifying clauses. Halliday includes here the various
English constructions of the equative type that are related to clauses.
One part consists of a nominalization, of which there are
two types (Halliday 1985: 280): a. THEME IDENTIFICATION and b. THEME PREDICATION.
The simple sentence John broke the window will therefore have
the following equivalents:
a. Theme identification
(69) What (the thing) John broke was the window.
(70) The one who broke the window was John.
b. Theme predication
(71) It was the window (that) John broke.
(72) It was John who broke the window.
The nominalized part of the identifying clause (what (the
thing) John broke, the one who broke the window; (that)
John broke, who broke the window) names what is to be
identified, the non-nominalized part gives the identifier.
Focussing This representation of Halliday's functional analysis of the foc.
it sentence is based primarily on Halliday (1985: chapter 3.7 and p.
280 f).