I suggest it's because the natural, non-pathological use of argument is to solve dilemmas one has with another party. In each case this means convincing the other of something.
- For a threat dilemma, I must convince them I mean to carry out my threat.
For a rejection dilemma, I must convince them I can't/won't accept their offer.
For a persuasion dilemma, I must persuade them they're better off accepting what I'm offering.
For a trust dilemma, I must persuade them to carry out what we've agreed
Politicians' arguments flout these norms. They're trying to demonstrate to a third party -- the voter -- that their opponent is stupid, malign & not the one to vote for. They don't want to change their opponent's mind at all, though they may claim to want to. They want the voter to think that what they themselves advocate is right & is opposed by their opponent. This view would be upset if their opponent were to change.
Intellectuals also enjoy arguments where each side tries to win & neither side gives in too easily. They are a way of testing ideas to find if they have serious flaws. A clever & motivated opponent may point to what's wrong with your theory.
But all this is very irritating to most people. It's pathological. The natural, drama-theoretic function of argument -- the reason we developed it through evolution -- is to persuade & convince each other. If we fail in this, our only recourse (within the family or between social units) is to violence. This is the natural way to behave.
The cultural norm of adversarial argument, where the aim is to ridicule your opponent & make them seem an idiot, began in the law courts of ancient Greece & went from there into philosophy & politics. It has had immense benefits for science, philosophy & the rule of law on which competition & capitalism are based. But unsophisticated members of our society, & all true members of other societies, don't like it. They don't care much for its products either, many preferring superstition to science, religion to philosophy, forgiveness to the rule of law & socialism to competition & capitalism.
This is my suggestion: the democratic, capitalist societies that dominate today's world are based on a culture of adversarial argument & competition that we are born to find repugnant. And the reasons are drama-theoretic.
