Problem
Let's say you're at home with your best friend watching meteorologist bloopers on YouTube, when someone knocks on your door. "Hello," he says, "my name is Ralph and I am a psychotic serial killer. I am looking for your best friend, because I would like to brutally murder him. Is he here right now? If he's not, I'll just go away and look for him somewhere else." What would you do here? What would Kant say you should do in this situation? Why?