There's a great line from a song by John Mellencamp.

"People believe want they want to believe when it makes no sense at all."

Science has proven that people with strong opinions on a given subject aren't swayed by facts that refute their beliefs. A recent article in The New Yorker cites a series of studies conducted at Stanford university, in which students were asked to discern between truthful information and deliberate deception. One group was told they nailed it almost every time, another was told they got it wrong nearly every time.

It was a ruse.

They were actually being tested on their belief that they were right. The results indicated once people form opinions, they're unlikely to be swayed, even by factual information.

To bring it home, those impassioned political discussions in social media are a waste of your time.