Most evil invention in the history of man

[Arthur Dent]

Most evil invention: The Guillotine.

The guillotine was invented by a doctor as a more humane way of executing people after he witnessed the attempt to execute a man with an axe. It took a dozen strokes to kill the man because the axe kept wobbling and hitting the guy in the shoulders and the back of the head or wouldn't go all the way through the neck.

Most evil invention would have to be someTHING (not a thought or philosphy) that has no other purpose but to cause pain, death and/or destruction.

I can think of a few chemical weapons that cause just about the most horrifying and painful death you could ever wish on a person.