Idiom:
Like a headless chicken ( chaotic situation )

Hit the book:
Why do people argue with other people?

1. As long as people have differing opinions there will be arguments, which isn't a bad thing. Not everyone is immature and close minded like your question seems to imply. Some people can actually consider the point of view of others, and admit that they have lost an argument. Also presidential debates are not to convince the other presidential candidate, it is to inform the public on the issues. When you have two people arguing different sides of an issue, the faults of both sides are more likely to be revealed, and can help to reveal the truth. Much of the American court system is based on this idea.

2. How old are you? People argue because they have different opinions. It is usually not a battle of egos. Winning an argument might inflate someones ego but the argument is about the issue.
Why do people running for the office of President debate? Because they look at issues differently and have different solutions to the problems. It allows those of us who actually think to consider the options and vote for the person who we see as having the better answer(s).
Arguing is standing up for what one believes in. People who don't have pretty passive personalities. A passive person doesn't get a whole lot accomplished in life.