A group of doctors were out duck hunting, when a large bird flew overhead.
The family doctor raised his gun to shoot, but then lowered his gun saying “I am not sure that is a duck.”
The psychiatrist raised his gun, but then lowered it again saying “I know it’s a duck, but I’m not sure that it knows it’s a duck.”
The surgeon raises his gun and blasts the bird out of the sky. He turns to the pathologist and says “Go see if that was a duck.”