I'm not sure I buy the theory about it originating in political discourse.
It's a very basic concept. Changing your mind almost necessarily involves admitting you were wrong in the first instance — if you do not admit it outright, someone else will likely confront you on it.
People don't like admitting they were wrong. It makes one look bad, and provides one's enemies with ammunition.
There's absolutely nothing wrong with changing your mind as your understanding evolves.