An Identity Is A Story

Ceci n'est pas un Bob.

After thinking for a long time about Kim Cameron's Laws of Identity, I gave a talk on Identity at the Burton Group's Catalyst conference last month. Jamie Lewis and Kaliya Hamlin (who blogged my talk) approached me after the session and urged me to start my own blog in order to join the online identity discussion. If you like what you read here, you should thank them for pushing me past my deep ambivalence about blogging.

Here's a little taste of what you might see here at ceci n'est pas un Bob over the next couple of weeks.

I think identity behaves in consistent and predictable ways in the real world, BUT most contemporary discussions of identity are completely out of touch with what identity really is and how it really works. To understand how identity behaves, it's necessary to distinguish the different uses people make of identity, and consider each of those uses individually.

I think a set of axioms of identity can be defined which describe what identity can and cannot do, and what it will and will not do in particular circumstances. We can enumerate these axioms by looking at centuries of thought about identity and examining that thought in the light of situations which occur in the real world today.

I think that systems designed with the axioms of identity in mind will be more effective than systems designed without regard for the axioms.

I think that the axioms define how identity and privacy are related, and can help illuminate when we can determine identity, when we can protect privacy, when we must choose, and when we are out of luck on both counts.

As usual, it's best to start with definitions.

IDENTITY

The problem of identity has a long and difficult history. Nietzsche, surveying that history, threw up his hands:

"Belief in the identity of different things, or in the identity of the same thing at different times, is a fundamental philosophical error"

This was already an old idea in the East, of course; Buddha denied the existence not only of identities but even of things before 500 BC.

The West conducted a nuanced discussion of identity for centures, until the industrial state decided that identity was a number you were assigned by a government computer. Aristotle's tortured treatment in the Topics set the stage for centuries of debate about what exactly it is that is "identical" in the identity of a person.

Serious modern discussions descend from book 2, chapter 27 of Locke's "An Essay Concerning Human Understanding", which distinguishes between the identity of a body, the identity of a man, and the identity of a person, and which makes the argument that the last of these is what is of interest in cases of law, because without continuity of memory and intent, there is no rational basis for the assignment of praise and blame.

Literature has mined the philosophical discussion deeply; mistaken identity is one of the great themes. Think of Twelfth Night, Dr. Jekyll and Mr. Hyde, The Man in the Iron Mask, Zorro, The Phantom of the Opera, and The Picture of Dorian Grey, for starters. If you haven't read it, Christopher Priest's "The Prestige" is a great recent addition to the genre.

If you want to follow the philosophical discussion into the modern day, start with "The Identities of Persons", by Amelie Oksenberg Rorty.

You should want to follow the discussion, because the twentieth-century statist notion that each person has an unchanging identity which can be observed by a third party (for example, a clerk at the Department of Motor Vehicles) and with which a number can be uniquely and persistently associated has broken down, and the consequences of the breakdown are intruding on your personal life, liberty, and privacy right now.

Don't believe me? Let's look at an example. ICAO is in the process of finalizing standards for incorporating biometrics into passports. The motivation for putting biometrics into passports is that better identification will help in "the war on terror". If the problem in the war on terror were preventing known terrorists from crossing national borders at official checkpoints using genuine passports issued in their own names, biometric passports might help.

But let's look at something Rorty says in her introduction:

"Why are we interested in someone being the same person, and not merely the same human being or physical object? One reason is primarily retrospective: we need to know whom to reward and whom to punish for actions performed when "they" were acknowledgedly different in some respects from the present population. But we have more forward-looking reasons as well: we want to know what traits remain constant so that we can know what we can expect from the persons around us. We assign crucial responsibilities to individuals, assume important continuing relationships to them in the belief that certain of their traits are relatively constant or predictible."

If you buy this argument, you're forced to conclude that "whether a person is the same physical object as at some past time" (which is what a biometric sensor measures) is not what you need to know, either to punish the person for a past misdeed or to predict whether they're going to do something bad in the future.

How much taxpayer money are you willing to spend on biometric passports before you know whether you believe this or not?

In the National Academy of Sciences Committee on "Authentication Technologies and their Privacy Implications", we tried to define terms like "Identity", "Identifier", "Attribute", "Identify", "Authenticate", and so on - as a contribution to settling these arguments before systems began to be designed and deployed. If you're interested in the topic you can read our entire report; if you want to keep up with the identity discussion you can just take a look at the definitions.

I still like our definitions very much, but I'm going to venture my own personal (new) definition of "identity" here. I think it's consistent with the committee's definition, but it's a lot catchier:

AN IDENTITY IS A STORY

It's that simple. One of the reasons it's simple is that I've left out lots of things which are commonly but falsely assumed about identities.

For example, I might have said "An identity is a story about a person". But this overconstrains the definition: lots of identities exist which are not stories about people. You know many of them:

• Captain James Tiberius Kirk
• Lara Croft
• The current King of France

I might also have said "An identity is a true story". But of course truth isn't a requirement for identity attributes. The only time Richard Nixon ever told you "I am not a crook" was after he had committed a crime but before he was pardoned for it. In almost every identity story, some elements are true, others are false, and others have an indeterminate status (that is, people disagree about whether they are true or not, but there is no way to settle the argument).

John Demjanjuk has been associated with at least three identity stories. These stories are inconsistent with one another, so they cannot all be true in all their particulars, but courts in two countries on different continents have been unable after extensive investigations to pick the stories apart and determine what's true and what's false.