> However, I very strongly suspect that no matter what the level of racism on Facebook is, it would be far higher if people were able to post anonymously.

Counterexample HN and arstechnica.com

As I have previously hypothesised a lot of good users (me included) seems to be scared away by real names policies.

Pseudonyms allowed and linked to phone numbers or national ids combined with karma seems like a workable middle ground for me.