It seems like this sort of privacy control could be put in place without resorting to pseudonyms.

For instance: you register using your real name/"authentic identity", but you select a restrictive privacy option that says that your profile won't show up when people search for your name on Facebook; nobody can friend-request you; and all your posts and other info is visible to friends only.

Voila, you now have a private profile, but the people whom you are friends with on Facebook don't have to create a user script that replaces your pseudonym with the name they actually know you by.

Do you trust facebook to respect all those settings in the future, or are they likely to implement a change to the system that defaults everything open? What about selling it to advertisers and other organisations?

I'm quite comfortable with the pseudonyms of my friends. Some of them are known by pseudonyms IRL, and one or two have names that don't match their ID but are the name they use in life and at work. More women than men; pseudonymity is a useful defence against ubiquitous harrasment.

You do know that for some years you could find people by phone number, even if they were hiding their profile from search?

And for Facebook’s Caller ID this API endpoint is still existing.

I'm pretty sure that you can already do all of this. I can't currently find the option to entirely de-list from search, but I thought I had it on before.

You can de-list pretty much all information about you - without a publicly visible profile picture and your current location (city/country), you're pretty much impossible to find among others who share your first and last name. And yes, Facebook has enough users now that if you live in a big city, it's likely you'll find a few people sharing your first and last name in the same city.

Unless you have a very uncommon name, or live in a smaller city. I live in a 280k city and everyone with my last name in the phonebook is related to me, and on Facebook only me, my sister, my uncle and my cousin have an account.

My full name exists less than a dozen times on Facebook in all of Germany, and the name does not occur anywhere in the world outside of northern Germany.

This is quite an issue.

I know many people with highly distinctive, and, in a surprising number of cases, entirely unique names. Some rather surprisingly.

Name plus city plus one other piece of data (approximate birth date, school(s) attended, former employer(s), a few other associates/contacts, profession) are very often enough to uniquely identify an individual, even with an otherwise common identity.

> (approximate birth date, school(s) attended, former employer(s), a few other associates/contacts, profession) are very often enough to uniquely identify an individual

Yes, but you can set all of those to private and thus effectively delist yourself from Facebook Search. The only thing that really has to be public nowadays is your name.