Martin (1992: 19):
The main problem with this treatment [of clause taxis and conjunctive cohesion by Halliday and Hasan] is that it fails to bring out the continuity of the structural (i.e. as soon as, because, whereas) and the non-structural (i.e. immediately, consequently, by contrast) resources.
This is not true. Systemic Functional grammar provides the means of understanding what they have in common as well as how they differ in function.
They differ in terms of metafunction: taxis involves logical relations between units in univariate structures (complexes), whereas conjunctive cohesion involves non-structural textual relations.
But textual cohesion involves the deployment of all the metafunctions for textual (metafunctional) ends:
- conjunction is the deployment of logical resources to textual ends,
- reference is the deployment of textual resources to textual ends
- substitution and ellipsis is the deployment of interpersonal resources to textual ends, and
- lexical cohesion is the deployment of experiential resources to textual ends.
Therein lies the 'continuity' between clause taxis and conjunctive cohesion.