There's a notable difference between writing a book and publishing an announcement that you're going to go on a killing spree. The former is relatively benign, the latter has far too often been done right before a killing spree. The former is done over time, in relative peace; the latter is done in the spur of the moment.
It's like writing the Anarchist's Cookbook about how to make a bomb, and writing a tweet about how you're going to plant a bomb in Boston in a couple minutes. The latter is a direct threat and requires immediate action. Most of the time, it's too late even for that.
Personally, this dude should've known better and restrain his impulsive internet lulz behavior.
>the latter has far too often been done right before a killing spree.
Basic Bayesian approach to probability tells us that this metric of predicting violent events is counter-productive due to a great number of false positives.
You may have good metrics on the number of incidents that were pre-dated with announcements, but you probably have very bad metrics on the number of announcements that were followed by incidents.
There's no way you can make a statement about how strong the link is without that information.
This man's facebook post alone, and especially absent of any kind of access to a gun, are no grounds to assume any actual intent to cause physical harm. Far from it, I would say artists who have a history of violent confrontation, write/sing/rap about stabbing, shooting, or otherwise assaulting other people, and actually are in possession of weapons they could use to do so, could be assumed by any reasonable person to be more guilty of actually having an intent, or at least an overzealous willingness, to cause harm to others.
