Ideally, racism online should be countered by real, in-person conversations between the offender and a more enlightened friend, family member, teacher, neighbor—someone, anyone who can explain what’s wrong about hating someone for being different than you. Oftentimes, however, those people don’t exist or aren’t around at the right moment, and the rest of the Internet-using public is all a racist’s got. But that’s not necessarily the worst outcome. Thinking prejudiced thoughts, even letting them slide out into the world, isn’t an unforgivable offense. The real tragedy would be allowing them to go undiscussed.
— How Do You Stop Racism on Twitter?, New Republic.