Greg Sargent: This is the deadliest mass shooting in modern U.S. history. How should we talk about it?

Another day, another mass shooting in America. Except this time, the horrific slaughter that unfolded Sunday night at a concert in Las Vegas is being widely described as the deadliest one in modern U.S. history. More than 50 people are dead, and more than 200 wounded, after the shooter opened fire on a crowd on the Las Vegas Strip from a 32nd-story hotel window.The shooter has been identified as 64-year-old Stephen Paddock, who is dead and is believed to have taken his own life. He lived in Mesq