How To Identify Topical Theme

In a free major clause, topical Theme is the first experiential element of a clause, whether participant, circumstance or process.

It's that simple.

Any textual or interpersonal elements that precede the topical Theme are also thematic.

There is only one topical Theme to a clause.

No clause has both a marked a unmarked topical Theme.

A topical Theme is either marked or unmarked.

If a clause has a marked topical Theme, such as a circumstance, then it has no unmarked Theme.

Foolish	are	they who unquestioningly believe that Subject is always unmarked Theme
Theme: marked	Rheme
Complement	Finite	Subject

Wise	are	they who can think critically and are alert to the absurd consequences of poor theorising
Theme: marked	Rheme
Complement	Finite	Subject

Halliday's Predicament

Kœstler (1979 [1959]: 433-4):

The inertia of the human mind and its resistance to innovation are most clearly demonstrated not, as one might expect, by the ignorant mass — which is easily swayed once its imagination is caught — but by professionals with a vested interest in tradition and in the monopoly of learning.  Innovation is a twofold threat to academic mediocrities: it endangers their oracular authority, and it evokes the deeper fear that their whole, laboriously constructed intellectual edifice might collapse.  The academic backwoodsmen have been the curse of genius from Aristarchus to Darwin and Freud; they stretch, a solid and hostile phalanx of pedantic mediocrities, across the centuries.

SFL Is A Dimensional — Not Modular — Theory

Halliday & Webster (2009: 231):

In SFL language is described, or “modelled”, in terms of several dimensions, or parameters, which taken together define the “architecture” of language. These are 

• (i) the hierarchy of strata (context, semantics, lexicogrammar, phonology, phonetics; related by realisation); 
• (ii) the hierarchy of rank (e.g. clause, phrase/group, word, morpheme; related by composition); 
• (iii) the cline of instantiation (system to instance); 
• (iv) the cline of delicacy (least delicate to most delicate, or grossest to finest); 
• (v) the opposition of axis (paradigmatic and syntagmatic); 
• (vi) the organisation by metafunction (ideational (experiential, logical), interpersonal, textual).

The mistaken notion that SFL is a theory of "interacting modules" can be sourced to Martin (1992).

(1) Martin (1992: 390);

Each of the presentations of linguistic text forming resources considered above adopted a modular perspective. As far as English Text is concerned this has two main dimensions: stratification and, within strata, metafunction.

See critique here.

(2) Martin (1992: 391):

Within discourse semantics, the ways in which systems co-operate in the process of making text is much less well understood. … A more explicit account of this co-operation is clearly an urgent research goal; English Text has been concerned not so much with addressing this goal as with making it addressable by proposing four relatively independent discourse modules to beg the question [sic] … . The point is that integrating meanings deriving from different metafunctions is not a task that can be left to lexicogrammar alone.

See critique here.

(3) Martin (1992: 392):

The modularity imposed by stratification is also an important issue. Discourse systems generate structures which in principle cut across grammatical and phonological ones.

See critique here.

(4) Martin (1992: 488):

In this chapter a brief sketch of some of the ways in which discourse semantics interacts with lexicogrammar and phonology has been presented. The problem addressed is a fundamental concern of modular models of semiosis — namely, once modules are distinguished, how do they interface? What is the nature of the conversation among components?

See critique here.

(5) Martin (1992: 490-1):

Grammatical metaphor then is the meta-process behind a text. It co-ordinates the synoptic systems and dynamic processes that give rise to text. It is the technology that let's [sic] the modules harmonise. It is their medium, their catalyst, the groove of their symbiosis, their facilitator, their mediator. It is the re/source of texture.

See critique here.

Time Phase vs Reality Phase

Time phase, as the name suggests, is the unfolding of the process with regard to time: starting vs continuing vs ending.   Reality phase, as the name suggests, is the unfolding of the process with regard to reality: unreal (apparent) vs real (realised). Halliday & Matthiessen (2014: 571):

At the deepest level time-phase and reality-phase are the same thing: both are concerned with the stages of becoming. A process is something that emerges out of imagination into reality, like the rising of the sun. Before dawn, the sun shines only in the future, or only in the imagination – as future turns into present, imagination turns into reality.

Bilingualism

Ergativity & Voice

Halliday & Matthiessen (2014: 333n):

Note that ‘transitivity’ is the name for the whole system, including both the ‘transitive’ model and the ‘ergative’ one. ‘Ergativity’ is thus not the name of a system, but of a property of the system of transitivity: within this system of transitivity, we can recognise the ‘transitive model’ and the ‘ergative model’

Halliday & Matthiessen (2014: 349):

A clause with no feature of ‘agency’ is neither active nor passive but middle. One with agency is non-middle, or effective, in agency. An effective clause is then either operative or receptive in voice. In an operative clause, the Subject is the Agent and the Process is realised by an active verbal group; in a receptive [clause] the Subject is Medium and the Process is realised by a passive verbal group.