Feb 5, 2015 · 2 minutes

Twitter chief executive Dick Costolo knows the service has a problem with harassment, and in internal memos obtained by the Verge, he takes full responsibility for the issue.

Costolo made his comments after a Twitter employee shared an excerpt from Lindy West's story about how a troll found an image of her dead father, created a Twitter account with the image as its profile picture, and used it to send hurtful messages.

Harassment is becoming an increasingly public problem for Twitter and other social companies. GamerGate showed how vile trolls can be; an article about how women are made to feel unwelcome on the Internet rightly won a National Magazine Award; and so on.

Here's some of what Costolo had to say in his mea culpa:

I'm frankly ashamed of how poorly we've dealt with this issue during my tenure as CEO. It's absurd. There's no excuse for it. I take full responsibility for not being more aggressive on this front. It's nobody else's fault but mine, and it's embarrassing.
We HAVE to be able to tell each other the truth, and the truth that everybody in the world knows is that we have not effectively dealt with this problem even remotely to the degree we should have by now, and that's on me and nobody else. So now we're going to fix it, and I'm going to take full responsibility for making sure that the people working night and day on this have the resources they need to address the issue, that there are clear lines of responsibility and accountability, and that we don't equivocate in our decisions and choices.
That's sure to be a daunting task. Google recently explained how hard it is to monitor all the content uploaded to YouTube in real-time, and while it was talking specifically about screening for extremist content, the same issue applies to digital harassment.

It might be harder to preemptively weed out harassment for another reason: it's hard to define. Should companies use the old porn rule ("I know it when I see it") or the adage that a person's liberty to swing their fist ends just where another's nose begins?

People have different thresholds for what they consider harassment. Twitter currently avoids this issue by asking users to report what they consider harassment, but as these memos and the stories mentioned above show, that approach is no longer sustainable.

These are complex issues, and Twitter is sure to be criticized no matter what it does to tackle them. But seeing the chief executive of a public company take responsibility for such a big problem, and committing to address it, is a good place for change to start.

[illustration by Brad Jonas]