This is a pretty odd remark. The effect of living with one kidney isn't some sort of unknown thing we need to reason about from first principles, we know pretty

This is a pretty odd remark. The effect of living with one kidney isn't some sort of unknown thing we need to reason about from first principles, we know pretty well what life is like for kidney donors. And I don't know about 'really have to', but it doesn't seem like 'saving someone's life' is a trivial or stupid reason.