Once you provide a constraint on what you mean by "good" or "bad" (in this case, an ethical viewpoint e.g. utilitarianism), doesn't the discussion immediately b

Once you provide a constraint on what you mean by "good" or "bad" (in this case, an ethical viewpoint e.g. utilitarianism), doesn't the discussion immediately become uninteresting? At most, you can debate whether or not your understanding of utilitarianism (or whatever constraint you choose) is accurate, but you've made no progress as to whether or not the constraint itself is "better" or "worse" than any other arbitrarily-chosen constraint.