A professor has given a lecture this evening in which he claims that our behavior is the product of our genetic make-up. We don't really have free will. We're pretty much at the mercy of our genes which means that we're not really responsible for what we do.
A psychopath has managed to kidnap the professor and challenges him to defend this thesis in the real world. The video, titled Cruel Logic, is pretty grim but as you watch it ask yourself, given the assumptions of the professor, what answer could he make to the psychopath's challenge.
If you were in the professor's position what could you say to save your life? Does the psychopath's behavior make sense if the professor is correct? If man truly is morally autonomous what's actually wrong with the psychopath's behavior, beyond the fact that we just don't like it?
The only way to resist the conclusion that there's really nothing wrong with what he's doing is to deny the premise that our behavior is genetically determined and that morality is a completely subjective phenomenon. But, in the absence of an objective, transcendent ground for moral behavior there is no answer.
As philosopher Richard Rorty once said, the secular man has no answer to the question, why not be cruel. Ideas do indeed have consequences.