A form of scientific theory used in the popular movie: Monty Python and The Holy Grail.
We found a witch! May we burn her?
A witch? How do you know she's a witch?
She turned me into a newt!
I got better..
There is a simple way to figure out if she is a witch or not.
Witches burn, and what else burns?
Yes, and wood floats. What else floats?
... A duck?
Yes! So if this woman weighs as much as a duck, than she is a witch!