[ I should point out that as well as being eminently spinnable - and a copy's sent there - this topic is (yet again) being discussed on comp.risks/RISKS-L, where it is a frequent visitor because of the tendency of US organisations to use social security number (SSN) as a unique and "safe" password or identifier. ]

Tavia wrote:

why one single (and trackable) identity?

Well, for one thing, computers. Much of the push has been because the police have database, the inland revenue has them, insurance companies, social security, child car, etc, etc. And they're all wrong, to some degree. It seems sensible to tie the information in, so that you don't have to tell your tax office when you move, the hospitals know about your national insurance contributions, etc, etc. Ignoring for a second whether that's a good thing, and looking at it purely as a data management exercise, it's hard enough making sure the records tie up correctly when there's just "one" identity for each person (typos, other people with same names, out of date records being linked to another person, etc.) Throw in multiple names, and it becomes much harder.

Surely I should have the right to putter round doing my lawful business under as many different identities as it pleaseth me ? And if I want to concoct a new one for the hell of it, then why not?

But in the eyes of the law, these are just tags you've acquired. They're still assuming that there's only one, physical lump of biological matter wandering around being "you", whatever it wants to call itself. That uniqueness needs preserving.

Back to risks, though - Joanne wrote:

when all that's really required is some sort of card which has a name, a photograph, and a signature on it.

Alas, that's not enough, because it's amazingly easy to forge. Social engineering is mostly the problem, because while you want a single means of identification to make the system reliable and predictable, it also means you have a single point of failure for an attacker.

steve