Halliday & Matthiessen (2014: 578-9):
We shall now turn to hypotactic verbal group complexes of expansion that also include a feature of causation. Such complexes are involved in the realisation of the transitivity system of AGENCY. We saw in Chapter 5 that there is a causative element in the structure of the English clauseFor example, John rolled the ball can be interpreted either as ‘John (Actor) did something to the ball (Goal)’ or as ‘John (Agent) caused the ball (Medium) to do something’.
We can always express this agency analytically, by saying John made the ball roll, where made ... roll is a hypotactic verbal group complex. Here the causative verbal group complex is thus an alternative realisation of the feature of ‘effective’ agency: an additional participant is introduced into the clause through the expansion of the verbal group realising the Process. In the ergative analysis this looks the same as John rolled the ball; but in the transitive it does not, and this enables us to interpret the difference between them: in John rolled the ball, he acted directly on it, whereas in John made the ball roll he may have done so by leverage, psychokinesis or some other indirect force (Figure 8-9).
As always, it is the combination of the two analyses, the transitive and the ergative, that gives the essential insight.
Blogger Comments:
The transitive interpretation of the participants in John rolled the ball as Actor and Goal contradicts the discussion (pp351-2) where the participants of such clauses (the police exploded the bomb, the sergeant marched the prisoners) are interpreted as Initiator and Actor.