We don't know what happened. We don't know if they were bombs or boilers. We don't know if someone was angry at Boston in particular or at tax day or at anything else.
The explosions at the Boston Marathon appear deliberate but we can't be sure yet and it's a worthwhile reminder of how little we know. Just this week it looked like an Aryan prison gang was responsible for gunning down two public prosecutors in Texas. Now the leading suspect is a cranky county employee they prosecuted.
After the 2011 mass shooting in Norway, some rushed to blame Islamic extremists when it turned out to be a Norwegian extremist. When a plane crashed in Queens days after 9/11 it looked like another terrorist attack on New York City but it wasn't.
In an age of instant communications and instant terror, falsity travels with greater speed than fact. The only thing that is certain is that one of the landmark events of American sport has been marred forever, that the 26th mile of this legendary race was dedicated to the victims of Newtown, Conn. and that we should pray for our fellow Americans in Boston.