Do-Support, the rule that supplies the auxiliary do to use with these rules.
(Auxiliary do carries the tense, so the main verb is changed to an infinitive)
In modern English Do-Support is obligatory; i.e, we can't ask questions like
Here, this is certainly archaic/literary style, and as such acceptable. 'Have' is the main verb (= 'possess', 'have with them'), not the auxiliary. // I'd say do-support isn't quite obligatory nowadays; 'Have we not a duty to these people to ...' is acceptable, and 'rhetorical', almost 'epic', rather than 'literary' in register. [226 000 Google hits for "Have we not a duty to"]
– Edwin AshworthFeb 21 '20 at 11:28
Do-Support, the rule that supplies the auxiliary do to use with these rules. (Auxiliary do carries the tense, so the main verb is changed to an infinitive) In modern English Do-Support is obligatory; i.e, we can't ask questions like
*Slept you 8 hours yesterday? any more. >> ...
– Edwin Ashworth Feb 21 '20 at 11:23