In my opinion there are about 4 good reasons to debate.

1. You get your reasoning/facts/opinions straightened out in your own head.

2. You get to test them against other reasoning/facts/opinions.

3. You somewhat force other people to think.

4. You spread organized information (topics of debate, arguments, points to arguments, etc)

Somewhere along the line, you have to change your beliefs or opinions, or learn something. If you have an argument and you test it against someone else's, and fail, you have to rethink you argument. If it was worded incorrectly, try correcting it. If your reasoning is wrong, there will be no way to fix it...

Cognitive Dissonance is something that everyone deals with. It means basically that you hold multiple ideas, and some of these ideas are in conflict with each other. Debating is a great way of smoothing out your ideas (or abandoning some) in order to relieve cognitive dissonance.

"Only the wisest and stupidest of men never change." - Confucius

Sure, I've learned a lot, and been forced to look stuff up I wouldn't have bothered to.

Certainly on some subjects many are simply gonna believe whatever they believe (no matter how many times I show a public option would almost have to work better than what we have)

by the same token though, I'll never be convinced Obama is a Nigerian Manchurian candidate planted by socialist/fascist/muslim terrorists in an attempt to enslave all white people to their black masters.

So what are ya gonna do?

I think that's why we do it. As Bradford said, you're testing out your assertions. Sometimes you're forced to rethink your ideas, and that's a good thing.

Yes, it can, if you have an open mind and you aren't just trying to prove how smart you are. Debating/discussing is good for two things: Changing minds and opening minds. What's the difference? Opening minds doesn't necessarily mean changing them, it just means making them understanding to other ideas and perspectives.

So yes, debate can change minds, but only if they are willing to be changed, and if the debate isn't so vicious that some people end up holding defensively to their views and closing their minds more.

It depends. There are some topics where I am going to keep my views regardless of what you say, and there will be others where I will completely change my stance. It definitely reinforces my views though, and makes sure I have an argument or evidence or whatever for them.