Definition of theirs (or ours) not to reason why in US English:

theirs (or ours) not to reason why

phrase

  • Used to suggest that it is not someone's (or someone else's) place to question a situation or system.

    • ‘It all seems as unregal as it is legal, but ours is not to reason why.’
    • ‘Theirs not to make reply, theirs not to reason why, theirs but to do and die.’
    • ‘In all likelihood they took on board the soldiers' dictum of ‘ours not to reason why’ and just got on with it.’
    • ‘Her lot is not to reason why.’