"How Do I Convince People They are Wrong?" - here's a question I get a lot from Engineers
Humans' brains are biologically wired to perceive "you're wrong" as a threat, so the only responses you're going to get from telling someone "you're wrong" are: fight, flight or freeze.
None of these responses help people understand they are wrong.
The short answer is:
In order to show someone they're wrong you have to first listen to them to understand, not listen to respond.
Then, only once you have understood their view of the world, will you be able to show them your view of the world by linking your arguments to the things they said.
Ah, and another thing:
Don't prove to them they're wrong in front of others, they will be more stubborn and less cooperative then.
Take the meeting off line and meet them one to one (again, biologically wired not to be shown wrong in front of the "tribe").