On There Being No Important Difference Between The Terms 'Realisation Statements' And 'Realisation Rules'

Fawcett (2010: 86n-7n):

Halliday prefers the term 'statements' to rules', but there is no difference of substance here. Following Hudson's pioneering work on realisation in Hudson (1971), I use the term "realisation rules". Strictly speaking, what Halliday refers to here as "realisation statements" are 'realisation operations', because it is possible for the realisation statement for a given feature to include two or more such 'operations'.

Blogger Comments:

[1] This is misleading, because it is untrue.  On the one hand, Halliday's term 'realisation statement' is consistent with the notion of systems as probabilistic, since probability is a modality of statements. 

On the other hand, Fawcett's term 'realisation rules' construes commands, the agnate modality of which is obligation. This is inconsistent with both modelling systems as probabilistic and with the fundamental view of language taken by SFL theory: meaning as choice.

[2] To be clear, this is a non-sequitur.  Fawcett's argument is as follows:

Premiss: a realisation statement for a feature can include two or more operations,
Conclusion: realisation statements should be called realisation operations.

On the one hand, the Premiss is false, because, in Halliday's model, each individual realisation statement constitutes only one 'operation', not two or more.  On the other hand, the reasoning of the argument is invalid because it deploys the type of circular reasoning known as 'begging the question' (petitio principii), wherein the truth of the conclusion is assumed in the premiss, namely: that realisation statements are operations.