beyond its congruent mode, there is metaphorical complementarity: the ideational model offers a complementarity between the congruent mode itself and the metaphorical mode, making it possible to take some phenomenon as already construed and then reconstrue it as if it was a phenomenon of a different kind.
still in its congruent mode, there are systemic complementarities: the ideational potential offers systemic complementarities such as the ergative and transitive models of participation in processes, and the mass and count(singular/plural) models of quantity;
within this congruent mode, there is a fractal complementarity: the highly generalised semantic types of projection & expansion are manifested in complementary domains — those of sequences, figures, and participants; so that, for example, some phenomenon of experience construed as having temporal expansion might appear either as a sequence or as a configuration;
in the congruent mode of construing experience, there is a metafunctional complementarity: the ideational potential offers two complementary modes for construing experience — the highly generalised logical mode, with projection & expansion as the dominant semantic motifs, and the more particularised experiential mode, with its typologies of processes, things, qualities, and circumstances;
The ideational meaning potential embodies not one single semantic system but rather several such systems coexisting; in Firth's terms, it is a "system of systems" — in two distinct but related ways [internal complementarities and registerial variation]. …
[Internal] complementarities constitute one form of indeterminacy of the system — one that allows it to be "polysystemic" in the particular sense of embodying more than one way of construing experience.
It seems likely that all these different kinds of indeterminacy are what make it possible for the grammar to offer a plausible construal of experience — one that is rich enough, yet fluid enough, for human beings to live with. We should stress once again that the examples cited here are features of the ideation base of one particular language, namely English. No other language will be identical. Indeed the distribution of indeterminacies is likely to be precisely one of the features in which languages differ most, and even perhaps varieties within one and the same language. But every language depends on indeterminacy as a resource for meaning — even if our grammatics is not yet very clever at teasing it out.
There are of course many different contexts for all these indeterminacies, in different regions of the total semantic space. Certain types of ambiguity appear to be not so much artefacts of the realisation (not just grammatical puns, so to speak) but rather another kind of complementarity, where the grammar is as it were "having things both ways" — both interpretations have to be accepted at one and the same time. This is sometimes the case with Token + Value structures, in figures of being. These clauses are always ambiguous, if the verb is be, since this verb does not mark the passive; yet some depend on being interpreted both ways — particularly, perhaps, some proverbial sayings, Thus, one man's meat is another man's poison is both Token ^ Value 'what one person likes may displease another' and Value ^ Token 'what one person dislikes may please another'; contrast what's sauce for the goose is sauce for the gander, which can be interpreted only as Token ^ Value.
When two figures are linked into a sequence, by some logical-semantic relation, there is a rather wide range of possible semantic relations between the two: the relations of time and of cause and condition are particularly elaborated in this respect, but there are others besides — the manner, the matter, and so on. The distinctions among these relationships, however, may be to a greater or lesser degree neutralised, where one clause is construed as dependent on the other; this happens as the dependent clause moves from finite to non-finite status.
For example, in they get caught taking bribes the distinction that would be made in the agnate finite clause, among, say
they get caught if they take bribes,
they get caught when they take bribes,
they get caught because they take bribes,
is simply neutralised — it is not a blend of all three, nor is there any ambiguity involved. An intermediate degree of specificity, with partial neutralisation, can be seen in the non-finite clause with accompanying preposition, as in
they get caught for taking bribes.
What happens here is that the fact that there is a connection between the two figures is unequivocally construed by the dependency; but the nature of this connection — what kind of logical relationship is being set up — does not enter the picture.
In those figures where there is a second direct participant, some form of agency runs through all the different types of process; but agency is such a complex aspect of human experience that the grammar does not delineate it by a single stroke, but construes it by means of a fundamental complementarity, that between the transitive and the ergative perspectives. Thus figures involving two direct participants, such as Actor + Goal in the material, are aligned along two different axes: the transitive one, based on the potential extension of force (mechanical energy) from a doer to another entity; and the ergative one, based on the potential introduction of agency (causal energy) from another entity as external source. Thus the earthquake shook the house is construed both as 'earthquake + shake' plus optional Goal 'house', and as 'house + shake' plus optional Agent 'earthquake'. As always in cases of complementarity, certain parts of the region are more strongly aligned to one perspective, other parts to the other, but the total picture requires the confrontation of the two.
As we saw, the grammar distinguishes a number of types of process, material, mental, verbal and relational; the distinctions are made by a cluster of syntactic variables — the valency of associated participant roles, the class of entity that takes on each role, the potential for combining with other figures, the associated tense systems and the like. But since these variables "draw the line" at different places, there are areas of overlap, with mixed categories that share some characteristics with one group and some with another.
We gave the example of behavioural processes; these are a mixed category, formed by the overlap of the material, on the one side, and the mental or verbal on the other. Behaving is construed as a type of figure that (like the mental) typically has a conscious participant as the central role, and does not extend beyond this to a second participant; but, on the other hand, it does not project, and it has a time frame like that of the material. Thus behavioural processes lie squarely athwart a fuzzy borderline.
But, thirdly, within the overall construction of experience, the diversity of spheres of social action is realised by variation in the line-up of semantic features — that is, by variation in register. The probabilities are reset; and in some cases one or two "critical systems" are strongly affected in this way, such that the local norm skews the system, or perhaps even reverses the skewing set up by the global norm. It is here that we find future taking over as the unmarked primary tense in weather forecasting. As we said above, we define register variation in just these terms, as the ongoing resetting of probabilities in the lexicogrammar, which then functions to construe the ongoing variation at the level of the social process.
Secondly, systems have varying probability profiles, so that (in terms of information theory) they carry differential loads of information: the skewer the probabilities of the terms in a system, the greater the redundancy that it carries — hence the less we need to attend to its unmarked state. For example: it has been found that, in an English clause, positive is about ten times as frequent as negative (Halliday & James, 1993). What this means is that we build in to our sense of a figure the presumption that something is or something happens, rather than that something is not or does not happen; extra work has to be done if a process is being construed as negative. The same applies to future tense, as we saw: extra grammatical energy is required to assign a figure to the future.
Halliday & Matthiessen (1999: 557):
How would we summarise the significance of indeterminacy, from the point of view of the semantic construal of experience? It lies first and foremost, perhaps, in the general principle that is being proclaimed, if indeterminacy is a typical and unremarkable feature of the grammar: that 'this is the way things are'. Our "reality" is inherently messy; it would be hard to construe experience, in a way that was beneficial to survival, with a semiotic system whose typical categories were well-defined, clearly bounded, and ordered by certainty rather than probability. This is the problem with designed systems, including semiotic ones: as a rule, they fail to provide adequately for mess.
Blogger Comments:
Given the immanent view of meaning, which the authors espouse, 'messiness' can only be a property of semiotic systems themselves.
Synchronically (that is, viewed synoptically in this way as a meaning potential) a language is, as we have said, a probabilistic system: if we say that, in the grammar, there is a system of primary tenses past/present/future, we assume the rider 'with a certain probability attached to them'. But we do not, of course, speak or write with one grammatical system at a time. Systems intersect with each other simultaneously (we choose tense along with voice, polarity, mood, transitivity and so on), and they follow each other in linear succession (we choose tense in clause 1, again in clause 2, again in clause 3 and so on). Each instance has its environment, both of previous instances, and of simultaneous instances of systems with their own sets of probabilities.
We shall not attempt to discuss this issue here; except to refer briefly to what is one important aspect of indeterminacy, namely partial association between systems. We model the grammar as if each of these choices was independent that the choice of tense, say, is not affected by the simultaneous choice of mood. This may, in fact, be so; but when choice is made in two systems simultaneously, such that each serves as environment for the other, there is often a conditioning effect on the probabilities. This may be an indication of a change in progress, or it may be a stable feature of the overall system.
The significance of global probabilities in the grammar emerges in various ways, both historical and synchronic. Historical change in language is typically a quantitative process, in which probabilities in systems at every level are gradually nudged in one direction or another, now and again becoming categorical so that some systemic upheaval takes place. Each instantiation of a tense form, say, whenever someone is speaking or writing in English, minutely perturbs the probabilities of the system — because what we call "system" and "instance" are one and the same phenomenon, being observed from different depths in time.
There are, of course, more catastrophic types of change: languages become creolised, creolised systems in turn become decreolised, or a language ceases to be spoken altogether. At the "instance" end, a single highly-valued instance may exert a disproportionate effect: quotations from the Bible and from Shakespeare are familiar triggers of this "Hamlet factor" in English (in media discourse today almost every change is a sea change, which goes into our folk taxonomy of types of change).
But such qualitative effects take place against a background of microscopic quantitative pressures, the sort of nanosemiotic processes by which a language is ongoingly restructured as potential out of the innumerable instantial encounters of daily life — the "sheer weight of numbers", as we sometimes call it.
And in the ontogenetic dimension of history, the growth and development of language in a human child, an analogous dialectic can be observed: highly valued instances of text (rhymes, favourite stories and the like) interact with the quantitative pressures of the talk going on around (the child's access to the global probabilities — note that children do not begin learning the grammar by sorting out functional variation!) to yield a meaning potential that is a reasonable copy of the probabilistic system shared among the community.
This illustrates one very powerful feature of a probabilistic system of this kind: that it accommodates systematic functional variation. We have discussed the two text types, weather forecasting and recipes, as examples of variation in register: of the way in which the meaning selections in texts tend to vary systematically with their contextual function — their value in the social process. We pointed out that this variation is seldom categorical: except in very closed registers, or "restricted languages", no major options are likely to be totally excluded. What happens is that the probabilities are reset. This may be a relatively minor skewing affecting a large number of semantic features; but one or other system may stand out by being particularly clearly realigned, as happens with tense and with mood, respectively, in our two examples. We can in fact define register variation as the resetting of probabilities in the lexicogrammatical and semantic systems, including those in the ideation base. We observe these probabilities in the form of frequencies in the text;
What we are saying is that there is a global pattern of probabilities in English, including a probability profile of the tense system whereby the probability of future is (say) 0.1. The register of weather forecasting, however, sets up a local pattern in which the probability of future is (say) 0.5. This changes the meaning of the system of primary tense, because it reverses the marking and hence sets up a new relationship among the different terms. It construes a realm of experience in which the future becomes the familiar dimension of time, the point of reference by which both present and past are defined.
We have sometimes referred to the relative frequency of a particular feature of the grammar. For instance, in our two examples of the meaning base as a resource in language processing, certain patterns characteristically recurred: future tense in the weather forecasts, imperative mood in the recipes. In each case this was a special feature pertaining to the register in question: in weather forecasts, the future tense is especially frequent relative to the other primary tenses.
To say this means that there is a general expectancy in English discourse that, again relative to the other primary tenses, future will occur less frequently than it does here. In other words, there is some global expectation, in the grammar of English, about the relative frequency of the different terms in the primary tense system, past, present and future. Similarly there is some global expectation about the relative frequency of imperative and indicative mood. Frequency in the text is to be interpreted, therefore, as the manifestation of underlying probability in the system.
Local indeterminacies of all these types are found in all regions of the content plane, either within one stratum or at the interface between one stratum and another (including of course puns, which are formed at the interface of content and expression). Some of them involve very general categories, and hence resonate across wide stretches of semantic space, like the transitive/ergative complementarity. We may call them "local", however, in contrast to one global form of indeterminacy which is a feature of the entire system of language, and probably of any evolved semiotic system, namely its probabilistic character.
(5) Complementaritytransitivity (i): transitive perspectivedry = 'make dry' (cf. wipe)transitivity (ii): ergative perspectivedry = 'become dry' (cf. fade)
As discussed in Chapter 4 above, the grammar adopts two complementary perspectives on agency, the transitive and the ergative. Most processes are oriented primarily within one perspective or the other; here we have illustrated the complementarity with a verb that is at home in both.
Halliday & Matthiessen (1999: 551):
(4) NeutralisationIf the dependent clause in such an environment is finite, it selects one or other type of enhancing relation: condition, cause or time. If the dependent clause is non-finite, the distinction is partially or wholly neutralised.
(3) Overlap ('borderline case')
Behavioural processes such as listen, watch share some features with material processes ('present-in-present' as unmarked tense; no projection), other features with mental processes (the Medium/ Behaver is a conscious being). They lie on the borderline between 'doing' and 'sensing' (so can be re-iterated as do in some contexts but not in all).
(2) Blendthey might win tomorrow— ability 'they may be able to'x— probability 'it is possible they will'Here, on the other hand, the meaning of the oblique modal might combines the two senses of 'able' and 'possible', rather than requiring the listener to choose between them. If the verbal group is 'past', however, this again becomes an ambiguity:they might have won— ability 'they were capable of winning (but they didn't)'— probability 'it is possible that they won (we don't know)'
(1) Ambiguity(i) must:You must be very careful! (when you do that)
— obligation 'it is essential that you should be'
You must be very careless! (to have done that)
— probability 'I am certain that you were'
Here the listener/reader adopts either one interpretation or the other — usually, of course, without noticing that there is another possible meaning. In (i), the Attribute suggests the choice (one does not usually instruct someone to be careless!); but cf. you must be very sure of yourself ('before you do that'/ 'to have done that'). Compare also (ii), where the ambiguity is one that is typical of identifying clauses.(ii) home is where your heart is
— Token ^ Value 'if you live in a place, you love it'— Value ^ Token 'if you love a place, it is home to you'
There are perhaps five basic types of indeterminacy in the ideation base: ambiguities, blends, overlaps, neutralisations, and complementarities — although it should be recognised from the start that these categories are also somewhat indeterminate in themselves. What follows is a brief characterisation of each in turn:
(1) ambiguities ('either a or x'): one form of wording construes two distinct meanings, each of which is exclusive of the other.(2) blends 'both b and y'): one form of wording construes two different meanings, both of which are blended into a single whole.(3) overlaps ('partly c, partly z'): two categories overlap so that certain members display some features of each.(4) neutralisations: in certain contexts the difference between two categories disappears.(5) complementarities: certain semantic features or domains are construed in two contradictory ways.
We have tried to make the point that the human condition is such that no singulary, determinate construction of experience would enable us to survive. We have to be able to see things in indeterminate ways: now this, now that, partly one thing, partly the other — the transitivity system is a paradigm example, and that lies at the core of the experiential component of grammar.
What does it mean to say that a natural language is an indeterminate system? In the most general terms, it suggests that the generalised categories that constitute language as a system — as "order", rather than as randomness or "chaos" (let us say randomness rather than chaos, since chaos in its technical reading is also a form of order) — are typically not categorical: that is, they do not display determinate boundaries, fixed criteria of membership, or stable relationships from one stratum to another. We could refer to them as "fuzzy", in the sense in which this term is used in fuzzy logic, fuzzy computing, etc.; but we prefer to retain the term "indeterminate" for the phenomena themselves, since "fuzzy" is usually applied to the theoretical modelling of the phenomena (it refers to meta-fuzz rather than fuzz).
In the world of classical physics, the flux of experience was held under control: reality had to be prevented from wriggling, while it could be observed and experimented with. The control over experience is partly a physical matter; but it is also in part semiotic, and the semiotic control of experience is achieved by the nominalising power of the grammar. Since it is the grammar that has construed it in the first place, the grammar is able to transform it by reconstruing it in other terms. Grammatical metaphor played an important role in shaping our humanist world.
But it shaped it in a way which soon came to be felt as decidedly inhuman. Already at the end of the eighteenth century, within a hundred years of Newton's "Opticks", people were reacting against the rigidity of the world of physics; what they could not accept were the ideological constraints set up by scientific discourse, by a grammar which construed all experience in terms of things. In our own twentieth century the scientists themselves have become weary of it, finding that it prevents them from engaging with the indeterminacy and the flow that they now regard as fundamental — let alone with the concept of the universe as conscious and communicating, as something itself to be interpreted as a semiotic system-&>process. Once we conceive of reality in semiotic terms, it can no longer surprise us that language has the power to construe it, maintain it, and transform it into something else.
Halliday & Matthiessen (1999: 546):
We have shown that the motive for reconstruing experience in this way was in the first instance a textual one: in the grammars of these languages, when one is developing a reasoned chain of logical argument such that complex phenomena have to be given a clearly defined status in the organisation of information (the clause as "message"), such phenomena have to be constructed in nominal form. But there is no insulation between one part of the grammar and another, and this inevitably has ideational effects.
Any semantic construct that appears as topical Theme has a function in transitivity; if it is formed as a nominal group, it is potentially a participant in some process, and therefore at some level it is an entity, a thing. If we say diamond is transformed into graphite, this is a process involving two things, diamond and graphite; if we reconstrue this as the transformation of diamond into graphite it has become one thing, transformation, with diamond and graphite serving only circumstantially to qualify it as a thing of a certain kind.
This reconstrual of experience is complex: what were first construed as happenings have become things, with the original things now serving merely as their appendages; but at the same time what were first construed as logical relationships between processes have been reconstrued as processes in their own right. So the transformation of diamond into graphite is caused by ... .
It is also complex in another way: the original status accorded to the phenomenon is not lost, but enters into a metaphorical nexus with the new one. So transformation is still a process, as well as being a thing; is caused by, as well as being a process, is still a logical relation between processes. But, as we have seen, the overwhelmingly predominating effect of this reconstrual is a nominalising one, in which other phenomena are transformed into things. This is a major shift in ideational terms, and plays a significant part in the historical semiotic.
But to say that the semantic relations have become less explicit is to imply that these relations themselves have not changed. In one sense, this is true: we can "unpack" the metaphor, and experts will generally agree on how to do it. But in another sense it is not true.
Scientific discourse began, as we saw, with the creation of technical taxonomies and mathematical constructs; these were already modulating the semiotic construal of experience, even if only at the margins, by creating a new realm of abstract things that had not existed before.
But the transformation brought about by the renaissance was a more fundamental one; not only was this realm of abstract things greatly extended, but, more significantly, phenomena hitherto construed as processes and properties were now transformed into things — they were reconstrued, by grammatical metaphor. We have illustrated this transformation from English; but it took place in all those languages that took over the semiotic functions of medieval Latin.
We have suggested that the immediate context for this change was a discursive one: the evolution of a register of experimental science, in which certain forms of argumentation were highly valued. This is usually interpreted simply as the emergence of a particular genre, the scientific article; but that is only one side of the story — no such genre could have come into being without these changes in the grammar of the clause. At the same time, they have other significant consequences.
We have already pointed out the fact that one effect of grammatical metaphor is to render many of the semantic relationships implicit: if the happening is construed as a clause, the semantic relations are spelt out in the configuration of grammatical elements, whereas if it is construed as a nominal group they are not, or only partially so (compare his energy balance approach to strength and fracture with he investigated how strong [glass] was, and how it fractured, using [the idea that] the energy [...] balanced out).
On the whole, the greater the degree of metaphor in the grammar, the more the reader needs to know in order to understand the text.
When the processes and properties turn into nouns, the verbs do not disappear from the scene. Scientific discourse is still written in clauses, and these clauses still have verbs in them. Let us return briefly to the examples from Newton's "Opticks":
those Colours argue a diverging and separation of the heterogeneous Rays from one another by means of their unequal Refractionsthe variety of Colours depends upon the Composition of Lightthe cause of Reflexion is not the impinging of Light on the solid, impervious parts of Bodies
We might suggest a more congruent form of the first and second examples here:
colours vary because light is composed [in this way];
because those colours (appear] we know the heterogeneous rays diverge and separate from one another....
The verbs depend upon and argue both express a logical-semantic relation between the two nominalised processes: either an external cause, 'a happens; so x happens', or an internal cause, 'b happens, so we know y happens'. This is another grammatical metaphor; the congruent form of representation of a logical relation is a conjunction. The two types of metaphor work together, to construe the two processes as one: 'happening a causes happening x', 'happening b proves happening y'.
It is not the case, of course, that this type of construction had never occurred in English before; it had. But it was rare; whereas from the time of Newton onwards it gradually took over, becoming the most favoured clause type of scientific language — as indeed we find it today.
There are similar contexts [in Newton's Opticks] for expressions such as an inequality of Refractions, the impinging of Light on ... Bodies, the thickness of the Body, reflecting power in the passages cited above. The nominalised forms inequality, impinging, thickness are not technical terms; or rather, they are so to speak technicalised for the given instance, but they do not lose their semantic status as property or event. Why then are they reconstrued as nouns?The reason is to be found in the grammar of the textual metafunction. In order to function with the requisite value in the message, which means either as Theme or as focus of information, they cannot remain as complete clauses; they have to be "packaged" into single elements of clause structure, and the only available constituent for this purpose is the nominal group. Instead of being a process in its own right, light impinges on a body, the phenomenon in question is construed as a participant, the impinging of light on a body. It can then take on a clearly defined status in the grammatical construction of the discourse.
What is beginning to emerge here is a grammar for experimental science: a way of construing experiential meaning so that it can be organised textually into a form of discourse for the advancement of learning.
If we look at Newton's "Opticks", from which these are taken, we find that it consists of three simultaneous discourses interspersed. In one of these phases, Newton describes his experiments; in another he draws conclusions from the experiments; and in the third he provides mathematical explanations. … The examples just cited of grammatical metaphor are typical of the second phase. It is here that Newton is proceeding by logical steps through a reasoned argument; and he frequently needs to summarise the argument up to that point, or in anticipation of what is to come. A typical sequence would be the following:
… when Light goes out of Air through several contiguous refracting Mediums as through Water and Glass, … that Light … continues ever after to be white. … … the permanent whiteness argues, that …
The metaphorical nominalisation permanent whiteness summarises the earlier sequence of inductions.
Halliday & Matthiessen (1999: 542-3):
When we come to the writing of Newton, however, we find formulations such as the following:… by these two Experiments it appears, that in equal Incidences there is a considerable inequality of Refractions.
… the cause of Reflexion is not the impinging of Light on the solid impervious parts of bodies, but .. .
… if the thickness of the body be much less than the Interval of the Fits of easy Reflexion and Transmission of the Rays, the Body loseth its reflecting power.These contain a great deal of grammatical metaphor, contrast them with more congruent forms of expression such as
light is refracted unequally (even) when it falls at the same angle;light is reflected not because it impinges on the solid, impervious parts of bodies';if the body is much less thick than the interval between the points where the rays are easily reflected and (where they are easily) transmitted, the body is no longer able to reflect (light).
Why has the mode of expression changed along just these lines?
Halliday & Matthiessen (1999: 542):
This discourse first appears in English in the work of Chaucer, for example his "Treatise on the Astrolabe", written about 1391. Here we find the same linguistic resources brought into play: nouns as technical terms, and extended nominal groups. The former are partly technological (to do with the construction and operation of the astrolabe), generally Anglo-Saxon or Norman French, like plate, ring, turet (eye, or swivel), riet (from rete 'net', i.e. grid), moder ('mother', body of the instrument); and partly theoretical (from astronomy, mathematics or general methodology), mainly borrowings from Latin like altitude, ecliptik, clymat (climatic zone), degree, equation, conclusioun, evidence. The latter do not attain any spectacular length but involve the expected mixture of clauses and prepositional phrases, as in the same number of altitude on the west side of this line meridional as he was caught on the east side. This is clearly the discourse of organised knowledge; but it is not sharply set off from the language of everyday life.
It is with the "new learning" of the Renaissance that a distinct language of science begins to emerge, with a vastly greater dependence on grammatical metaphor. The earlier exercises in nominalisation had been abstract but only minimally metaphorical; there is a trace of grammatical metaphor in expressions like conclusion and the same number of altitude, but no more than is found in the language of daily life.
Halliday & Matthiessen (1999: 541-2):
The forms of scientific discourse developed by the Greeks were then taken over into Latin. Although Latin differed in certain significant respects (for example, it had no definite article, and it did not readily accept prepositional phrases as Qualifier in the nominal group), it was close enough to Greek, both linguistically and culturally, for this to present few problems. Most Greek derivational compounds could be calqued directly into Latin (e.g., peripherêia to circumferens ); Latin had its own stock of nominalising suffixes, like -atio(nem) and -mentum; and a reasonably similar potential for expanding nominal groups.
As Latin took over as the language of learning throughout the greater portion of Europe, it had already developed an equivalent semogenic power. In the mediæval period Latin continued to serve; but by this time, although its morphology was largely unchanged, it had taken on the semantic patterning of the vernacular European languages. So when Latin itself was replaced by these languages, the transition was not unlike that which had taken place earlier into Latin from Greek: first the Greeks developed new meanings in Greek form, then these meanings were taken over into Latin forms, then new meanings were developed in Latin, then these new meanings were taken over into the modem European languages, then new meanings were developed within these languages. Thus there was a continuous evolution in the discourse of technology and science: in each transition, one component of the system was preserved.
The second of the resources that was brought into play was a syntactic one, the structure of the nominal group. The nominal group of ancient Greek was very like that of modern English: it had a similar arrangement of elements around the Head noun, allowing both prepositional phrases and clauses in modifying function (with some difference of ordering), and included among its deictic elements one which was very close to the English the. Thus any noun could accumulate qualifying clauses and phrases which were explicitly signalled as defining, analogous to English the electrons in an atom, the angles which make up a triangle.
One context which demanded elaborate nominal group structures of this kind was that of mathematics, as scholars conducted more and more sophisticated measurements, for example in their attempts to understand planetary motion. Here is the English translation of a nominal group from the work of Aristarchus of Samos, sometimes referred to as "the ancient Copernicus" because he was the first to propose that the earth revolved around the sun:
the straight line subtending the portion intercepted within the earth's shadow of the circumference of the circle in which the extremities of the diameter of the circle dividing the dark and the bright portions in the moon move
This has 32 words in the original Greek (fewer than the English because the equivalent of of is the genitive case of the noun); note that it is only the Subject of the clause, which continues ... is less than twice the diameter of the moon.¹
¹ The one minor piece of linguistic engineering that had to be undertaken was to ensure that the prepositional phrases in such constructions were placed after the Head word rather than before. It was also possible for a qualifying expression to be inserted between the Deictic and the Head, equivalent to English the in an atom electrons; this has only a limited potential for expansion, as can be shown by rewriting "The House that Jack Built" in this format:
This is the that Jack built house.This is the that lay in the that Jack built house malt.This is the that ate the that lay in the that Jack built house malt rat.This is the that killed the that ate the that lay in the that Jack built house malt rat cat.
With the qualifying phrase or clause at the end, the structure branches "to the right" (using the linear metaphor derived from European orthographies) and there is much less restraint on adding further elements. On the other hand, the fact that it is possible to put the qualifying element before the Head, which in English it is not, helps to avoid some ambiguity in the bracketing, as this example shows: here, both (which is) intercepted in the shadow of the earth and of the circle along which ... are qualifying the word circumference, and the Greek makes this clear with the intercepted-in-the-shadow-of-the-earth circumference of the circle along which ... . The English translation cannot follow this ordering.
The first of these was their resource for creating technical terms. For systematic scholarship it is necessary to technicalise some of the words that are used, and this imposes two requirements: the words must be interpretable in an abstract sense, since they need to refer not to outward appearances but to the properties and principles that lie behind them; and they need to relate to one another in a regular and systematic way, so as to form stable taxonomies.
Ancient Greek was a language of settlement, in which the potential for this kind of development lay predominantly in the nouns; and there existed already a number of noun-forming suffixes by which words of other classes — verbs and adjectives — were transcategorised. …
Using … nominalising suffixes the Greek scientists created hundreds of new technical terms; and by combining them with other derivational resources they developed extended series of semantically related forms …
In this way they established the foundations of the lexical component of a technical discourse, and the principles on which it could be indefinitely extended.
Halliday & Matthiessen (1999: 539):
Why did such a significant development take place? The most important single factor was undoubtedly the evolution of science and technology. It is possible to trace the emergence of this pattern of grammatical metaphor back to the origins of western science in ancient Greece, and to follow its development step by step; each stage in the evolution of the grammar realises a stage in the evolution of a world view.
The philosopher-scientists of the ancient Greek world, Thales, Pythagoras, Anaximander and their successors, inherited a language with a grammar of the kind outlined above, in which experiential meanings were construed in clausal patterns as a balanced interplay of happenings and things; nouns enjoyed no special privileged status. In the course of their writings (and no doubt first of all in the course of their sayings, only we have no access to these) they distilled this into a language of learning. We do not know how much they reflected on this process; it is unlikely they engaged in any very explicit language planning. What they did was to exploit the resources of everyday Greek, its fundamental semogenic potential. In particular, they exploited two of its grammatical powers: the power of forming new words, and the power of extending grammatical structures.
It might be maintained that a pair of expressions such as in times of engine failure and whenever an engine failed are simply synonymous, and do not imply any reconstruction of experience. But there are two problems with this view.
One is that of history, referred to above. If neither had preceded the other, they could simply be free alternatives (though language is seldom so extravagant with its resources as this would imply!). But since one form of wording came first, it inevitably acquired a rich semantic loading. Since nouns evolved as names of classes of things, anything which is represented as a noun inevitably acquires the status of a thing, with the implication of a concrete object as the prototype. Thus in engine failure, the grammar has construed a thing called failure; and the nominal group then accommodates classes of failure (with another noun as Classifier), such as crop failure, heart failure and engine failure. Thus engine failure and engines fail are precisely not synonymous, because in engine failure the happening failure has acquired an additional semantic feature as the name of a class of things.
The second problem is that of sheer scale. If only odd, more or less random instances of this kind of metaphor occurred, they could have little effect on the system as a whole. But given the massive scale of this shift in the grammar, affecting as it does entire registers of modern English, it cannot simply be dismissed as meaningless variation. As we saw in Chapter 6, the metaphoric processes themselves are highly systematic; moreover they occur in typical syndromes, so that it is not just one aspect of the construction that is affected. Rather, the entire perspective is shifted sideways, so that each element in the configuration is reconstructed as something else. When this pattern comes to predominate throughout a large proportion of the discourse of adult life, it amounts to a fairly major resemanticising of experience.
Under certain historical conditions, such a theory [i.e. the congruent model] may come to be modified or reconstructed. No doubt there have been various more or less catastrophic changes in earlier human history which have brought about relatively rapid changes in language — relatively, that is, to the gradual evolution of the system that has taken place all the time. We have no means of knowing about these. But it seems likely that what we are here calling grammatical metaphor represents one such partial reconstruction, in which, in the context of science and technology, a rather different kind of "reality" is being construed.
Blogger Comments:
Note the much earlier emergence of lexical metaphor, and the rather different kind of "reality" it construed: the rich symbolism of the various mythic traditions.
"Congruent" is of course a contingent term. What it is saying is that, at the present moment in human history we can recognise forms of language which seem to represent a common coding of experience: this is the configuration that we referred to as "process + participant + circumstance" which is construed in grammars through some version of the trichotomy of verb, noun and the rest. If we relate this to English, it is the form of English that is learnt as a mother tongue, in which phenomena are interpreted clausally, in a kind of dynamic equilibrium of happenings and things.
The prototypical thing is a concrete object which can be related by similarity to certain other objects, such that taken together they form a class, like engines. The prototypical happening is a change in the environment that is perceptible to the senses, or a change in the senser's own consciousness. A process is a happening involving one or two such objects, or one object and a conscious being.
When children move from their own constructed protolanguage into the mother tongue, this provides a theory which they can use to give a plausible construction to their own individual experience.
From a purely descriptive point of view, each version is metaphorical from the standpoint of the other; there is no inherent priority accorded to either. Once we bring in considerations of history, however, a clear priority emerges; and it is the same priority whichever of the three diachronic dimensions we choose to invoke — the phylogenetic (history of the language), the ontogenetic (history of the individual) or the logogenetic (history of the text). In all these three histories, version (ii), the clausal comes first.
This form of construal evolved first in the history of English; version (i) emerged only as the result of a long process of later evolution. It comes first in the life of a child; children master version (i) only after a long (in terms of their young lives) process of becoming literate and being educated And it comes first in the unfolding of a text; we are much more likely to be told first that engines fail and only then to hear about a phenomenon of engine failure.
Once we take note of progression in time, then given a pair of such expressions we can identify one of the two as the more metaphorical. The process is one of movement away from what we referred to as a "congruent" form.
To recapitulate with a very simple example: Given a pair of expressions such as in times of engine failure and whenever an engine failed the two are related to each other by grammatical metaphor. A particular phenomenon has been construed (i) as a prepositional phrase with a nominal group as its Complement, (ii) as a hypotactic clause introduced by a conjunction; moreover, the lexical content has been construed in two quite different ways:
If we take just the question of which elements function as Thing, the two are exactly complementary: in (i) the Thing nouns are time and failure, while in (ii) the only Thing noun is engine. This relationship is analogous to that of metaphor in its usual, lexical sense; only here the transfer is not between words but between grammatical classes.
Many "spoken" languages may be realised in two different media: in speech, and in writing. At first this presents itself just as two modes of expression; but when we look more closely at discourse in spoken and written language we find regularly associated differences in grammatical construction. We find written language constructed in nominal groups, whereas spoken language is typically constructed in clauses. And since it is in the grammar that our experience is construed into meaning, what we are seeing are different forms of the construction of experience, one couched primarily in terms of figures, the other in terms of elements that make up such figures, mainly those that function as participating entities.
Our basic approach to this is embodied in the term "metaphor", as used in the context of metaphor in the grammar. We used the expression "grammatical metaphor" to refer to a complex set of interrelated effects whereby, in English and many other languages, there have evolved what seem to be alternative representations of processes and properties, in terms of word classes, meanings prototypically construed as verbs or adjectives come to be construed as nouns instead. But, as we saw, this is simply the superficial manifestation of a wider and deeper phenomenon affecting the entire construal of experiential meanings in the grammar.
Halliday & Matthiessen (1999: 535):
… the semantic system that is construed in (say) Australian or British Sign is not the semantic system of English, despite its being constantly permeated by English in the ways referred to above. It is a system needing to be described in its own terms, based on detailed studies of its grammar and discourse such as now being carried out for Auslan by Trevor Johnston. Such a description is designed first and foremost for the needs of the deaf community; but it will have general significance as a source of further insight into the semantics of spoken languages, making it possible to view them comparatively in the light of an alternative construction of reality.
From Sign, we can get further insight into the construal of experience as ideational meaning because of its greater potential for iconicity in the expression. Semantic space can be construed iconically in signing within a continuous space-time, constituted as bodily experience for the signer and as part of shared visual experience for signer and addressee.
From a comparative standpoint, spoken languages and deaf sign languages stand to each other in a metaphoric relationship, as alternative construals of a (largely, though not totally) shared experience. What appear at first simply as different modes of expression turn out to have, associated with them, somewhat different constructions of meaning.
Signers are also members of another language community, that of the (predominantly hearing) speakers of English, or whatever language is spoken around them; the two groups interact, and there is obviously no insulation between the two language systems. This gives rise to contact phenomena of two kinds: on the one hand, intermediate forms whereby English is realised in sign expressions (signed English, and finger-spelling), including a large number of new, "contrived" signs; and on the other hand, constant intrusion of English forms of expression, and therefore of English modes of meaning, into the sign language itself.
Gestural systems, by contrast, have a far greater potential for construing experience iconically. Thus in Johnston (1989: 16) "signs are roughly graded into four classes of transparent, translucent, obscure and opaque signs, depending on how iconic a sign is"; and while most signs fall in between the two extremes — Johnston grades them as obscure or translucent, rather than opaque or transparent — many of those he labels "obscure" have a popular explanation in iconic terms (e.g. 2388: n. CAMERA, v. TAKE A PICTURE, PHOTOGRAPH. Obscure action. Popular explanation: 'holding a camera and depressing the shutter button' [p. 301]). This suggests that even if particular explanations are "nothing more than deaf folklore" (p. 16), the system as a whole is perceived as prototypically iconic; and this feature is borne out in two important respects.
One is that many of the signs construing basic categories of experience that would be learnt very early in childhood, in the transition from protolanguage to mother tongue — examples are 1291 GET; 1479 HOLD; 1824 RUN; 2473 BIRD; 2759 DRINK, CUP; 36 BED; 163 UP — are clearly iconic, and so would tend to establish iconicity as the norm.
The other is that individual signs may be modified in a distinctively iconic fashion; e.g. 1471 "v LARGE, BIG, (with amplification) great, (with amplification and stress) enormous, huge, immense"; see in particular the section on "sign modification" in Johnston (1989: 494-9). As Johnston comments (p. 513), "A language which is itself visual and spatial has far more opportunities than an auditory one to map onto itself those very visual and spatial qualities of the world it wishes to represent".
We have referred all along to the primarily visual nature of human experience: how much of it is constituted as location, and especially movement, in space. Now, both gestural and vocal resources involve positioning and moving the organs of articulation in space; but the position and movement of the vocal organs, besides being largely out of sight of the listener, is very much mote constrained; and while this permits a limited degree of iconicity (association of close vowels with 'small', open with 'large', for example) this can never be more than a marginal feature of the system as a whole. Thus even allowing for the additional iconic potential of loudness and length, the expression systems of spoken languages must remain prototypically conventional. This is the familiar principle of the "arbitrariness" (i.e. conventionality) of the linguistic sign.
Halliday & Matthiessen (1999: 533):
In the most immediate sense, as regards their potential for construing signifiers — elements of wording and their arrangement in combination — both these forms of expression, vocal and gestural, are open-ended. Neither of them imposes a limit on the inventory of morphemes or their configuration in grammatical structures. Nevertheless they are significantly different in the kinds of resource they offer for making meaning. Perhaps the major difference between the two is their potential for iconicity.
Halliday & Matthiessen (1999: 533):
From one point of view, as we introduced it in the earlier discussion, Sign will appear as a realisational variant: that is to say, the meanings of language — its semantic system — may be construed either in sound or in gesture. There are, in fact, sign systems that are constructed along these lines: in principle this is what is meant by "signed English". But if we consider the nature of the two forms of expression, vocal on the one hand and gestural on the other, it is clear that they have very different properties. Gesture operates in a 3-dimensional "signing space" defined by reference to the signer's body and its parts, and movement within that space is entirely accessible to the receiver, thus in addition to succession in time (which is common to both), the gestural medium can exploit a number of parameters of spatial variation: the "articulatory organs" (fingers, hands, arms, other body parts), their location, orientation, thrust (direction and speed of movement) and so on.
These three "metafunctions" are interdependent; no one could be developed except in the context of the other two. When we talk of the clause as a mapping of these three dimensions of meaning into a single complex grammatical structure, we seem to imply that each somehow "exists" independently; but they do not. There are — or could be — semiotics that are monofunctional in this way; but only very partial ones, dedicated to specific tasks. A general, all-purpose semiotic system could not evolve except in the interplay of action and reflection, a mode of understanding and a mode of doing — with itself included within its operational domain. Such a semiotic system is called a language.
For a fuller understanding of the clause, we have to recognise that it evolved simultaneously as reflection, as action and as information: that is, not only as a representation of the phenomena of our experience but also as a means of social action, of moving around in interpersonal space (and so defining that space and those who occupy it); and as a semiotic construct, whereby language itself becomes a part of, and a metaphor for, the reality it has evolved to construe and to construct.
As far as the textual metafunction is concerned, therefore, any one clause will typically embody two sets of semantic choices. One will be its organisation as a message, a piece of information flowing from speaker to hearer, its limits defined by the speaker's point of departure and the focus of attention projected by the speaker on to the listener. The other will be the cohesion it sets up with the preceding moments of the discourse, as well as with other discourses and with the total semiotic environment. These enable the clause to function effectively as reflection and as action.
But in the course of serving this enabling role, the textual component opens up a new dimension of meaning potential, in that it construes a further plane of "reality" that is as it were made of language — meaning not as action or as reflection but as information. In the modern world, when we increasingly live by exchanging information, rather than by exchanging goods-&-services as hitherto, this aspect of meaning potential is coming more and more to be foregrounded But it has always been there; and this is not the first time in history that it has proved to be an indispensable resource.
Lexical cohesion refers to cohesion that is brought about by lexical means: choosing a word that is related in a systematic way to one that has occurred before. The range of semantic relations that can create cohesion in this way is very wide; but there are five principal conditions under which it occurs. These are: repetition, where the speaker simply repeats the same word; synonymy/antonymy, where a word is chosen that is similar or opposed in meaning; hyponymy/meronymy, where a word is chosen that is related by 'kind of' or 'part of — either vertically, like melon ... fruit or car ... wheel, or horizontally, like melon ... plum, or wheel ... mudguard; and collocation, which does not necessarily imply any particular semantic relationship but means simply that a word is chosen which is regularly associated with a previous one, like aim coming shortly after target, such that a resonance is felt between the two.
In conjunction, the various logical-semantic relations of expansion that construe clause-complex structures (discussed above under the "logical" metafunction) are deployed instead as a source of cohesion. There are a large number of such conjunctive expressions, ranging from single words like however, moreover, otherwise (many of them originally composite forms) to prepositional phrases like in that case, in other words, at the same time (often containing a reference word inside them). They cover more or less the same range of meanings that we referred to as "elaborating", "extending" and "enhancing"; but they do not establish any structural relationship in the grammar, and this is recognised in written English, where they regularly occur following a full stop.
In ellipsis, some features which are present in the semantic construction of the clause (or other unit) are not realised explicitly in the wording, which cannot then be interpreted unless these features are retrieved from elsewhere. Here it is not the meaning that is being referred to; it is the wording that is being retrieved, usually from the immediately preceding clause (whereas reference can span considerable distances in the text). Ellipsis is particularly characteristic of dialogue, especially adjacency pairs such as question and answer. Sometimes in English a substitute element is inserted as a placeholder; e.g. ones in Which lanes are closed? — The northbound ones.
Halliday & Matthiessen (1999: 530-1):
Reference is a way of referring to things that are already semiotically accessible: either actually, in the text, or potentially, in the context of situation. The English reference systems are the personals, especially the third person pronouns and determiners he/him/his she/her/hers it/its they/them/their/theirs, and the demonstratives this/these that/those and the maverick the (which emerged as a weakened form of that). Such systems evolved in a deictic function; when used anaphorically or cataphorically (that is, in deictic relation to the text), they create cohesion. There is also a third source of referential cohesion, through the use of comparison, with words such as same, other, different, less, smaller.
Over and above its contribution to the grammar of the clause, what we are calling the "textual" metafunctional component comprises a further set of resources, which construe clauses and clause complexes into longer stretches of discourse without the formality of further grammatical structure. These are the resources for creating "cohesion". These are of four kinds: reference (sometimes called "phora", to distinguish it from reference as defined in the philosophy of language), ellipsis, conjunction, and lexical cohesion.
All languages display some form of textual organisation of the clause. How far this kind of speaker - listener complementarity, with a quantum of information being construed out of the tension between the two, is a general or prototypical feature of this aspect of the grammar is not at all clear.
In Austronesian languages, for example, there is typically a much more complex pattern of interrelationship between the textual and the ideational structures of the clause (mapping of Theme on to different transitivity roles) than is found in Indo-European. Even with regard to English, where it is well established how the flow of information is engendered in the grammar, opinions differ as to how far this should be seen as one continuous movement and how far as the intersection of two different periodicities (as we are inclined to interpret it).
It may be a general principle that thematic status is more closely tied to the clause (as the locus of experiential and interpersonal choices) than is the listener-oriented pattern of given and new; in English the "quantum" of information that is defined by this latter construction is not, in fact, identical with the clause and may be smaller or larger. But all discourse is organised around these two motifs, which between them "add value" to the clause, enabling it to 'mean' effectively in the context in which it occurs.
Halliday & Matthiessen (1999: 529-30):
But the "Theme + Rheme" configuration becomes a message only when paired with another one, that of "Given + New". This construes a piece of information from the complementary point of view, as something having news value — something the listener is being invited to attend to. It may not contain anything the listener has not heard before; a great deal of "news" is totally familiar, being simply contrasted or even reiterated. On the other hand, the entire message may consist of unknown information, for example the first clause of a piece of fiction.
But the message is construed along prototypical lines as an equilibrium of the given and the new, with a climax in the form of a focal point of information: 'this is to be the focus of your attention'. This focal point usually comes at the end; but (unlike the Theme + Rheme) the Given + New structure is not signalled, in English, by word order — it is signalled by intonation, and specifically by pitch prominence, the point of maximum perturbation (falling, rising or complex) in the intonation contour. The principle behind this is clear: if the Theme always came first, and the New always came last, there would be no possibility of combining them; whereas one powerful form of a message — powerful because highly marked — is that in which the two are mapped on to one another, as in no wonder they were annoyed (where the focus is on the interpersonal theme no wonder).
From the speaker's point of view, a piece of information has a specific point of departure; the Prague scholars referred to this as the "Theme". The Theme, in English, always includes one element that has an experiential function, typically a participant in the process; it may include other elements as well, for example an interpersonal expression of modality if the speaker is thematising his/ her own point of view. One way of signalling what is thematic is by putting it first in the clause, as is done in English, where everything up to and including the first experiential element constitutes the speaker's chosen point of departure; for example But surely time is defined as that which you can't turn back?, where the Theme is but surely time. Here the speaker is construing a message around the theme of 'what I'm saying is contrary to what went before' (but); 'it's my opinion, and I'd like to challenge you with it' (surely); and 'the starting point is the topic of time'. The remainder of the clause constitutes the body of the message, labelled grammatically as the "Rheme".
Since these resources are oriented towards discourse, many of the "textual" systems in any language have a domain potentially higher than the clause and clause complex; they set up relationships that create semantic cohesion, and these ate not restricted by the limitations of grammatical structure.
But they also contribute a critical dimension to the overall grammar of the clause. In this guise, the clause functions as a quantum of information; it is construed as a message, with a range of possible structures providing for different interpretations according to the discourse environment in which it occurs.
These structures have been less fully described than those of the other metafunctions; they were brought to the notice of grammarians by Mathesius and his colleagues of the Prague school in the first half of the present century. But it seems that one typical way of construing the clause as a message is as a combination of two perspectives, that of the speaker and that of the listener (the latter, of course, being also as modelled for the listener by the speaker).
The "textual" metafunction is the name we give to the systematic resources a language must have for creating discourse: for ensuring that each instance of text makes contact with its environment. The "environment" includes both the context of situation and other instances of text. Relative to the other metafunctions, therefore, the textual metafunction appears in an enabling role; without its resources, neither ideational nor interpersonal constructs would make sense.
Interpersonal meaning is mapped on to ideational meaning at all points from the most micro to the most macro: from modality and speech function in the clause (or even features built in to the morphology of the word, like the diminutives characteristic of many languages) to settings affecting the whole of a particular register, like the aura of power and distance that we associate with the language of bureaucracy. These are the various ways in which language functions as a mode of action; and these meanings, no less than ideational ones, are brought into existence by the grammar.
Halliday & Matthiessen (1999: 527):
Some particular interpersonal colouring may inform the whole of an individual speaker's interaction with another person; and because human societies are inherently hierarchical, the interpersonal component of the grammar in many languages enacts networks of social relationships with varying degrees of inequality and of distance. Thus there may be regular lexicogrammatical variants used to maintain different alignments of speaker and listener, and even of third parties, on vectors of power and familiarity; such forms may be located at one point in each grammatical structure (for example in the endings of the verb) or dispersed prosodically throughout the wording of the clause.But even in a language such as English, where there are no such systematic speech styles institutionalised in the grammar, there is always some functional variation along these lines: we have no difficulty in recognising what are the more formal and what are the more informal variants among different samples of spoken or written discourse.
Halliday & Matthiessen (1999: 527):
Unlike ideational meanings, which tend to be located at definable locations in the grammatical structure, interpersonal meanings tend to be strung throughout the discourse, by an accumulation of grammatical and lexical features or by other devices such as voice quality and intonation contours. This signals the fact that interpersonal meanings are more diffuse: they relate to the figure as a whole, rather than to one of its elements; or to a whole turn in the dialogue, or even to some more extended passage of the discourse.
Modality is a rich resource for speakers to intrude their own views into the discourse: their assessments of what is likely or typical, their judgments of the rights and wrongs of the situation and of where other people stand in this regard. But there are numerous other kinds of interpersonal meaning constructed by the resources of the grammar. These include comments about how desirable or plausible or self-evident something is, expressions of attitude in referring to persons and objects, sets of words with similar experiential meaning but distinguished interpersonally by connotation (sometimes called "purr words" and "snarl words"), and numerous forms of personal address and reference (kinship terms, personal names, honorifics, endearments, insults and the like).
Halliday & Matthiessen (1999: 526):
The latter [derived from the polarity of proposals] occupy the dimensions of "obligation" and "readiness", readiness including both inclination and ability; for example,They ought to clean this place up. People will leave it so untidy.— They can't; they haven't got the equipment. They're not supposed to clean it anyway.— You mean they won't. But someone must. Can we?— I don't see whey we shouldn't. Will you help?Although these are derived from the sense of proposals ('you are required/supposed/allowed; I am able/willing'), they are not restricted to clauses having these speech functions; obligation and readiness are construed by the grammar propositionally and hence are used freely with third persons. But they still represent the judgments of speaker or listener on the obligations or inclinations involved (he ought to help, she will help).
Halliday & Matthiessen (1999: 526):
The former [deriving from the polarity of propositions] are along the dimensions of "probability" and "usuality", the first being the more elaborated of the two (because more arguable); for example,That was a snake.— It wasn't. It can't possibly have been a snake.— Couldn't it? Don't you think so? I think it might have been.— It probably wasn't. But snakes can appear round here.All of these represent probability except the final can which means 'sometimes' (usuality). Note that it is always the judgment of speaker or listener that is represented as a choice of modality, not that of any third party (this is one of the boundaries drawn between 'me-&-you' and 'the rest').
Languages differ considerably in their construction of this space, and in the extent to which they interpret it grammatically. In English, there are four distinct grammatical traverses between 'yes' and 'no', two deriving from the polarity of propositions ('it is/ it isn't') and two from the polarity of proposals ('do! / don't!').
The mood system constructs the clause as a move in an argument: either as a "proposition" (statement or question) or as a "proposal" (offer or command). The system provides scope for argument by incorporating an opposition of 'on' or 'off': each clause assigns either positive or negative polarity. Every proposal or proposition selects one or the other: either that was a snake or that wasn't a snake, either catch it! or don't catch it! But at the same time the interpersonal grammar goes much further, it rejects a simple polarity of 'yes' and 'no', opening up a broad semantic space in between. This is the area of "modality", where the interactants present different aspects of their own judgments and opinions, exploring the validity of what is being said and typically locating it somewhere between the positive and negative poles.
Halliday & Matthiessen (1999: 525):
Note in this connection that the basic distinction constructed by language is not, as sometimes claimed, that between 'me' and 'the rest'; it is that between 'me-&-you' on the one hand, and the rest — the 'third party' — on the other. This distinction is coded in the grammar at many places, for example in the system of modality; there can be no "first person" unless there is a "second person" with whom these roles can be alternately acted out.
Halliday & Matthiessen (1999: 525):
If the ideational metafunction is language in its "third person" guise, the interpersonal is language in its "first and second person" guise; the interaction of a 'me' and a 'you'. The 'me' and the 'you' are of course constructed in language; they have no existence outside the social semiotic. Once constructed, me and you then become a part of experience and can be referred to alongside the him, the her and the it; but note that (unlike their interpersonal meaning, which does not change) their ideational meaning changes every time there is a change of speaker (this is what makes me and you so difficult for children to learn).
Choosing a particular speech function is, obviously, only one step in a dialogue; what the grammar creates, through the system of "mood", is the potential for arguing, for an ongoing dynamic exchange of speech roles among the interactants in a conversation. The mood system, together with other systems associated with it, constructs a great range of speech-functional variation; and since in principle any ideational meaning can be mapped on to any interpersonal meaning, this makes it possible to construe any aspect of experience in any dialogic form.
If the commodity being exchanged is goods-&-services, then the action that is given or demanded is typically a non-verbal one: what is being exchanged is something other than a construction of meanings, and the meanings serve to bring the exchange about. In principle the listener need not say anything at all; but listeners usually do, typically by reversing the role, responding to an offer with a command and to a command with an offer
If on the other hand the commodity being exchanged is information, then this is in fact made of meaning; the speaker's action, and that of the listener if responding to a question, is bound to be a verbal one, because here language is not only the means of carrying out the exchange, it is also the nature of the exchange itself.
