In the days after the worst mass shooting in modern American history, one crucial question has remained unanswered: Why? Why would 64-year-old Stephen Paddock shoot into the crowd at a country music festival, killing at least 58 people and injuring over 500 more? Why would he plan his attack so carefully? Why would he book other hotel rooms for other dates and in other cities

What was his motive?

So far, answers to these questions have been scarce and unsatisfying. The Islamic State claimed responsibility for his actions, though that has drawn skepticism from experts. Trump said the shooter was “a sick man, a demented man,” though there’s been no evidence that Paddock suffered from mental illness. And evidence has emerged that he was gambling thousands of dollars a day in the weeks before the shooting.

“I think it’s kind of rare [to not know a motive],” said George Bonanno, a clinical psychologist at Columbia’s Teacher’s College who studies how people respond to traumatic events. Bonanno and Michigan-based disaster mental health specialist Susan Silk, who has volunteered with the Red Cross after several disasters, answered some of Newsweek’s questions about how that lack of motive is affecting how we are coping with this tragedy. (Their answers have been lightly edited and condensed.)

How will the recovery process differ for survivors of events like this one compared to others for which there was a link to a terrorist group or another clearer motive?

George Bonanno: There’s no way that this is not going to be an extremely painful, disturbing event to anybody just because of the horrific nature of it and the scale of it. I think it would actually be even more difficult if it were a jihadi or someone with this platform of vitriol. There is some evidence that when [the victim] feel hate…it makes it harder to recover from an event.

Would the psychological recovery from an event like this be different than from other forms of disasters, like natural disasters?

Susan Silk: In 2017, we certainly have had a slew of natural disasters. People are disoriented, people are disrupted, but in very, very few cases is there any real amount of anger. But when things are man-made—when there’s a murder or a mass homicide—there’s certainly a sense of outrage.

GB:  After a natural disaster, you don’t have the sense of someone doing something to you. You don’t have this sense of interpersonal violation. Bad things happen; it’s scary and it’s painful, there’s loss of life and resources involved. It throws your life in turmoil for a long time. But you can partially explain it to yourself as, These things happen. But when somebody does something to you, it’s harder to explain it.

In the absence of a motive, what else can survivors and the broader community reach for to help understand the tragedy? 

SS: I think it stirs up the big philosophical, existential questions about human nature. Mostly, I think we don’t come up with very good answers. And I think that’s disturbing. We almost want to find out that someone’s been wronged or abused and they feel like this was their only recourse. I think it probably does contribute to processing the event.

GB: You could start ruminating on that and why did he do it to me, why did this person do it, and you start turning over and over in your mind different explanations. Rumination is typically something we see when people don’t recover very well. Their mind is churning about why did it happen, it shouldn’t have happened. All kinds of counterfactuals. “If we only had better gun laws, if we only had better gun laws.” There’s more stuff to think about that you have to struggle with then.  

What about people who weren’t present at the shooting or who lost a loved one?

GB: I think it probably makes it a little bit easier to put it out of your mind—that he wasn’t an avowed terrorist. I’m based in New York, so if you’re in the subway, you can think to yourself that a terrorist attack could happen here. The shooting in Las Vegas wouldn’t send shock waves through people thinking that now it’s going to happen here, because there isn’t a larger group associated with the event as far as the public knows.

SS: Starting with the victims and their immediate family and then the people who are on-site observing this and then people who could imagine themselves having been there, who were on the Strip a week ago—that’s the sort of thing that you can’t just walk away from. I don’t think there’s that kind of intense vicarious reaction when it’s a natural disaster as when it’s manmade. But I think we need to emphasize that by and large, most people are quite resilient. In general, by talking to people that they know, by doing good self-care and psychological first aid, most people will recover.