[Megan] Sorry for all the reader mail, but it's unusually good this weekend.  A reader on the problem of publicising mass killings:

I'm sure that desire for notoriety is a factor is such killings as went on at VA Tech (especially because he sent a video to NBC), but I don't think that's usually a driving motivation.  The danger of over-reporting (or reporting at all) killings like this is what Cialdini calls "social proof."  In his book "Influence," Robert Cialdini details how in the time following most well-publicized suicides, the rate of motor vehicle and small aircraft crashes increase by a factor of 5.  He hypothesizes that these are actually suicides, for various reasons that I won't go in to now.  But the point is that social proof is a powerful motivator, even in matters of life and death.  Social proof is the idea that if somebody else is doing something, it's more likely that it's a good idea.  You see it all the time in advertisements (anything that says "over 4 million people use our toothpaste" or other such nonsense).  So the more we publicize mass killings like at VA Tech, the more other people might think it's a good idea and actually do it.  It's a scary thing, and a powerful argument for limiting the amount of facetime we give to mass killers.