Fawcett (2010: 283):
We replace the 'rank scale' claim by the statement that
(1) the five major classes of unit (i.e., the clause and the four classes of group) all occur quite frequently at a number of different elements of structure within a number of different classes of unit;(2) that they do so with varying degrees of probability, and(3) these probabilities (and others) need to be represented in the grammar.
Thus 'absolute' rules can be seen as extreme cases of probability.
It is an interesting side-effect of defining classes of unit by their internal structure that it becomes impossible to apply Halliday's criterion of the unit's potential for operation in the unit above it on the 'rank scale'. One must choose one criterion or the other.
The generalisations captured in the diagrams in Appendix B suggest the value of basing classes of unit on their internal structure, and the corollary is that the description is able to show that all the major classes of unit (the clause and the four groups) can all fill several different elements.
Blogger Comments:
[1] This is misleading, because statements about relations between formal units and elements of structure cannot replace the the rank scale approach to constituency, because the rank scale is only concerned with the composition of formal units — a clause consists of groups ± phrases which consist of words which consist of morphemes — not with the relation between formal constituents and the elements of structure that they realise.
In theoretical terms, the rank scale is concerned with composition (extension) at the same level of symbolic abstraction, whereas form-function relations obtain across different levels of symbolic abstraction related by intensive identification (elaboration).
[2] To be clear, as previously noted, the clause is a unit, not a class of unit (e.g. adverbial clause), putting the lie to Fawcett's oxymoronic claim that the Cardiff Grammar features classes of units (cf dog breeds) but not units (cf dogs).
[3] This is misleading, because it misrepresents a theoretical inconsistency in Fawcett's model as "an interesting side-effect". The theoretical inconsistency lies in the fact that a functional theory classifies units from above, like Halliday, not from below, like Fawcett. Moreover, it is the non-arbitrary relation between classes of group and phrase (e.g. nominal group) and the meanings they realise (e.g. participant) that makes an interpretation of the functions of grammatical forms possible.
[4] To be clear, a functional theorist chooses Halliday's criterion, whereas a formal theorist chooses Fawcett's criterion.
[5] To be clear, this is a bare assertion, unsupported by evidence. The diagrams in Appendix B merely illustrate Fawcett's model of structure; this alone does not "suggest" the value of taking a perspective that is inconsistent with a functional approach to structure.
[6] This is misleading, because a corollary is a proposition that follows from one already proved, whereas Fawcett's next proposition does not follow from one that has been proved; see [5].
[7] This is misleading, because it misrepresents a mere description of the model as a theoretical advantage of the model.