Well, if the negative concerns things that by nature are impossibly self-contradictory, say married bachelors or police intelligence, then they disprove themselves. But as you say, the exercise is an unnecessary shifting of the burden of proof.
At the age of five, Skagra decided emphatically that God did not exist. This revelation tends to make most people in the universe who have it react in one of two ways - with relief or with despair. Only Skagra responded to it by thinking, 'Wait a second. That means there's a situation vacant.'
