Why do we hold our opponents in contempt? Former British politician Douglas Alexander believes that disagreement is good - it is how the best arguments get refined. But, today, public discourse has become so ill-tempered, snide and lacking in respect that we are no longer engaged in a battle of ideas but a slanging match. Time to dial down the rhetoric, rein in the insults - they will persuade no-one that your opinion is worth listening to - and pay attention.