In the Wall Street Journal, David Kopel is probably right that the "copycat effect" of cable news and social media explain the surge in mass shooting incidents over the past decade.
But that fact points in a very different direction from the one in which he wants to go, which is to absolve America's permissive gun regime. Modern media won't be uninvited. The Internet isn't going away. Since those institutions will, as he says, "greatly magnify the instant celebrity that a mass killer can achieve," it becomes more important than ever to prevent mass killings in the first place.
And while more stringent mental health standards can play a part, the fact is that with mass killers we are looking for rare individuals amidst millions and millions of people with mental health problems. Stricter gun licensing and tighter controls upon the deadliest weapons are in fact the least intrusive and most cost-effective way of reducing gun violence. Kopel is certainly right that a sign on the door proclaiming a school a "gun-free zone" is useless. But that uselessness does not imply we need more guns. It implies that we need more than mere signage to keep the guns out.