Both the metaphor and its literal application only make sense if "cannot" and "does not" means "never", and they really don't.
While I'd never fear the mind of a man who literally is in a coma and doesnt think at all, I'd have plenty of reason to fear the mind of a man whose ability to think is merely limited. He can be a stupid moral reasoner and a clever killer at the same time.
In that case, though, you're afraid of the man's axe more than his mind.
Another month has passed and here is a new rationality quotes thread. The usual rules are: