Pigeon

An unintelligent person that sticks to their unfounded ideas without evidence or statistics no matter the argument given contrary to their beliefs.

The Pigeon is often the subject referenced in the saying "Arguing with an idiot is like playing chess with a pigeon, no matter what you say, they will knock over the pieces, crap on the board, and strut around like they've won."

"Flat Earth has been proven time and time again to be false, yet these Pigeons keep promoting the belief"

"I was arguing with this Pigeon earlier, it was like talking to a wall."