Facebook set theory

Forced to register either my mobile number or add a credit card to my Facebook account (for “funding sources”: yeah, right I’m going to give you that info to store on your servers!) I went to check my privacy settings. And here’s where my relationship with Facebook splinters somewhat. I’ll let you look at the picture first.

Got that? I can show various facets of my (largely fictional) digital life to:

• Everyone — presumably all Facebook users, whether I know them or not.
• Friends of friends — I guess that’s people Facebook thinks I “know” and their immediate next tier? Or maybe their friends too?
• Friends only — pretty self explanatory: people I have accepted and state I know.
• Other — erm… so these would be… wait… umm…

In mathematical set theory, this is perhaps a paradox or, at the very least, something worthy of a university thesis. Since ‘Everyone’ is the whole set of almost 1 billion Facebook users, should I infer that ‘other’ is:

• the remaining 5 billion people from the Universal Set of humanity?
• people who aren’t my friend?
• members of the animal kingdom?
• aliens?

If it’s none of the above, perhaps that column should be renamed?