There is no both sides

There is no both sides 
yet there is always debate.
Why would someone lie?

Note: A science-based approach, questioning, forming a hypothesis, using observation and experimentation, and analyzing, results in a single result. That would mean that in bothsidesism, one side is a lie, not based in fact. The next step? Find the motivation for the lie.  I would argue that it's often power or money, definately something selfish.