Something I've wondered over the last year or so: do serial killers have a function? Or are they an unfortunate concentration of traits that add up to monstrosity? Or did serial killers once have a function, which they now no longer serve?
It's another way of restating free will vs. predestination, I guess. Because if people who become serial killers have or once had a function that somehow benefitted the species (or a group within the species) as a whole, then they are somehow predestined to do the things they do (as are we all).
What personality tests do is say, "This is who you are. This is what you should be doing with your life. This is your function."
But it's one thing to try to assign everyone a blanket purpose in their lives, and it's another to try to find a purpose for child molesters, rapists, murderers...