> We can prove many of them don't have consciences.

Some recovered coma-patients would like a word with you.

Proving the absence of something like that is going to be pretty difficult (teapot, god) because what we're capable of is usually proving the existence of something.

I think drewcoo's point was that "having a conscience" and "having consciousness" are not the same thing. They were pointing out that the wrong word was used with a joke.