(a) In terms of discourse semantics, Martin (1992: 199) analyses the logical relation in the following instance as concessive purpose:
Ben can train hard without improving his time.
In terms of lexicogrammar, on the other hand, the logical relation in this instance is not a type of enhancement (purpose), but the type of extension termed addition: adversative — X and conversely Y — as shown by the paratactic agnate Ben can train hard and not improve his time. See Halliday & Matthiessen (2014: 471-6).
There is thus a "tension" between discourse semantics (concessive purpose) and lexicogrammar (adversative addition). However, despite this tension, this does not constitute an instance of grammatical metaphor. The tension, rather, is between an understanding of logico-semantic relations and a misunderstanding of them.
(b) In terms of discourse semantics, Martin (1992: 203) analyses the logical relation in the following instance as manner: comparison: contrast:
Whereas usually we win, this time we lost.
In terms of lexicogrammar, on the other hand, the logical relation in this instance is not a type of enhancement (manner), but, again, the same type of extension as in (a): addition: adversative — X and conversely Y.
There is thus, again, a "tension" between discourse semantics (contrastive comparison) and lexicogrammar (adversative addition). However, despite this tension, this does not constitute an instance of grammatical metaphor. The tension, again, is between an understanding of logico-semantic relations and a misunderstanding of them.
The notion of grammatical metaphor as 'stratal tension' requires the establishment of discourse semantic systems that are not "in tension" with the lexicogrammar in order to identify those cases that are not metaphorical.
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The notion of grammatical metaphor as 'stratal tension' requires the establishment of discourse semantic systems that are not "in tension" with the lexicogrammar in order to identify those cases that are not metaphorical.
