A debate is an activity between two or more individuals placed in two or more parallel or opposing sides to provoke one another to think and to speak for the purpose of creating more knowledge, discovering truth and to come to decisions.
A debate is a way to find more sides to an issue, with the express purpose of establishing that any human thought or understanding is not absolute. A debate happens so there is learning; about how much you know, how much others know and how much each can learn from the other.
Debate also is a way to discover that knowledge is unlimited and nobody knows it all. It is also to develop better perspectives and to understand things in a 360 degree manner by looking at all sides and not discounting any side before claiming to have a better understanding of the subject.