Say agree, not believe
Ask 'Do you agree?' not 'Do you believe?' Belief triggers religion and semantics tangents. Agreement keeps the conversation on stated values.
Weak: Do you believe humans should respect other animals?
Strong: Do you agree that humans should respect other animals?
Protein / health sincerity test
If protein, iron, or B12 is the excuse: if that were not a problem, would you live vegan from now on? Unless they say yes, the health objection is not genuine. Do not play the science game with studies.
Justice is not up for debate
Debating whether this is right implies justice is optional. Do not debate at cubes — not plants, lions, semantics, or philosophy. Repeat accountability questions.