Here is the quiz:

Imagine yourself in the following scenario:
You’ve just returned home from a day at work. While you set your keys on the kitchen counter and remove your coat you can hear the familiar voices of your roommate and her/his S.O. in the other room.
You start to wonder about what you might make yourself for dinner when suddenly you are startled by a loud gunshot, followed by what sounds like a body falling to the floor. Rather than getting the hell out of there you somewhat foolishly run to the other room to see what happened. Once there, you see your roommate standing there, arm outstretched, holding a still-smoking pistol pointed at what is now, apparently, a corpse.
Your roommate looks at you and says “Santa Claus did it.”
Do you:
a) Sincerely believe that your roommate is telling the actual truth?
b) Decide that, because you didn’t actually see your roommate fire the gun, you just can’t know one way or another whether Santa did it?
c) Consider your roommate a murderer, and the claim to be the rationalization of a mind that has snapped?

Yes, I initially have to go with c and act accordingly. Subsequent evidence may validate an alternate conclusion but that is not relevant to the scenario as presented.
Read the rest and comment here.
Via Pharyngula.