[coldtea]

>Usually people don't have them to learn - they have them to teach.

Doesn't matter IMO.

Both sides are still getting something out of it. Even if they just try to "teach" and think they already know everything, they also get to hear the argument of the other side, and think counterarguments -- thus improving their argument too.

In other words, even if they stick to their a priori beliefs no matter what, they at least learn to defend and define them better, because of having to deal with the other side.

Besides, a discussion is not just something to "learn" from. It's also entertaining on its own, a way to express yourself, hone your thoughts and so on. Learning from the discussion is not required for those things.

Not everything has to have an end goal, or "improve" us.