On 'Structural It' Not Realising A Participant

Martin (1992: 129-30):

One of the most common classes of nominal group not realising a participant is structural it, which appears where English needs a Subject to show MOOD but for various reasons has no appropriate participant around to fill this grammatical function.  Theme predication and impersonal projection both make use of it in this way; it is "structurally cataphoric" in both examples below:

THEME PREDICATION (Halliday 1985: 59-61)

[3:64] It was the frog he lost.

IMPERSONAL PROJECTION (Halliday 1985: 153, 245):

[3:65] It's likely he's lost his frog.

Meteorological it was included, following Halliday & Hasan (1976), under generalised reference above; it is however a borderline case, and could just as well be treated as not realising a participant at all, parallel to the examples in [3:64] and [3:65].

Blogger Comments:

[1] This misunderstands the functional motivation for such wordings.  Clearly, it is not the case that there is "no appropriate participant around"; see below.

[2] To be clear, in the case of theme predication, the it serves as the Head of a nominal group, of which the final embedded clause is Postmodifier.  Halliday & Matthiessen (2014: 199):

In Theme predication, the final clause is a relative  clause functioning as Postmodifier to the it (where it means ‘the thing that’, ‘the time that/when’, and so on).

it	was	the frog	[[ he lost ]]
Theme			Rheme
Sub-	Finite	Complement	-ject
Mo-		Residue	-od
Va-	Process	Token	-lue
nominal			group
Head			Postmodifier

In this instance, the nominal group with it as its Head realises the participant Value.

[3] On the one hand, this is an instance of interpersonal metaphor.  A congruent wording would be:

probably	he	's	lost	his frog
Adjunct	Subject	Finite	Predicator	Complement
Mood			Residue

On the other hand, in the metaphorical wording, the it constitutes a nominal group in apposition with an embedded fact as postposed Subject.  Halliday & Matthiessen (2014: 199):

The clause as postposed Subject, on the other hand, is a fact clause; and it is related to the it by apposition (paratactic elaboration).

it	's	likely	[[ he's lost his frog ]]
Sub-	Finite	Complement	-ject
Mo-		Residue	-od
Car-	Process	Attribute	-rier
nominal group			(embedded fact as) nominal group
1			= 2

In this instance, the nominal group complex of it = he's lost his frog realises the participant Carrier.

[4] Here Martin claims that these uses of it make cataphoric reference, but, in contradiction, claims that they do not serve as participant, the entry condition to 'reference as semantic choice' (IDENTIFICATION). 

[5] This is true.  Halliday & Hasan (1976: 53) treat 'meteorological it' as generalised homophoric reference.  Since this it does not realise a participant — see [6] — it demonstrates, on the one hand, that 'participant' is not the entry condition for reference, and on the other, that Martin is inconsistent in treating this as generalised reference in his system.

[6] Meteorological it is the only one of these three examples in which it is genuinely not realising a participant; see Halliday & Matthiessen (2014: 341).

it	is	raining
Subject	Finite	Predicator
Mood		Residue
	Actor / Process: material

[7] As demonstrated above in [2] and [3], this is not true.  The it in [3:64] is the Head of a nominal group that does realise a participant (Value), and the it in [3:65] is the initiating nominal group in a complex that does realise a participant (Carrier).