Lena Dunham and the cast of Girls stand up for the Stanford sexual assault victim

The powerful letter from the woman who was sexually assaulted by Brock Turner on the Stanford campus has raised a lot of important questions about rape and sexual assault.

How could a man convicted of a crime so horrible, against a woman who was so obviously unconscious that two passersby tackled Turner to stop him and alert the police, get off with such a light sentence?

And, as a new public service announcement from the cast of HBO’s Girls asks, why is it so hard for people to believe rape victims even though rape is so common?

The four stars of HBO's Girls — Lena Dunham (who has previously spoken out about her own rape), Allison Williams, Jemima Kirke, and Zosia Mamet — explain just how common rape and abuse are: About 1 in 5 women have reported being raped at some point in their lives, mostly by someone they already know, and 1 in 4 girls are sexually abused before the age of 18.

“This isn’t a secret," the women take turns saying. “It’s reality. So why is our default reaction as a society to disbelieve, or to silence, or to shame?”

Then they ask another question: "What if we chose to turn toward those in need, instead of away? To listen? To support? You have the choice to make things better."

It’s an important message, and advice worth heeding. Sometimes the simplest thing you can do to help victims is to listen to them and believe them — because, unfortunately, disbelieving and shaming rape victims tends to be our cultural default.

But there are also other concrete steps you can take, the cast members say — from calling out a hurtful remark to offering a ride so a victim can seek medical care or counseling.

Perhaps most powerfully, the Girls cast reminds viewers that women who are sexually assaulted deserve support and respect, “not because she is someone’s daughter, or someone's girlfriend, or someone’s sister. But because she is someone."

That’s one reason the Stanford victim’s letter was so widely shared and struck such a chord. It was a tremendously eloquent reminder that this woman is someone, and that other victims are too.