If I have the right key then I can unlock the door.
If P then Q.
I can't unlock the door, therefore I don't have the right key.
Not Q then Not P.
*Edit. Ha, I haven't proven a negative here have I!
On further reflection I can see a bit of my issue here...
"You can't prove a negative" looks like it's a self-refuting statement.
Did I read the post wrong? Did it mean that "you can't prove a negative" itself is a fallacy?
Edited by JadeEast - 10/18/12 at 9:47am