The problem of identity

One of the key aspects of database design is coming up with a unique identity for each record in the database. This may seem like a simple database design problem, but it actually has significant impacts on life in our society.

Numerous problems occur when unique identity is not possible. Take for example the problems the airlines have been having with mistaken identity on the no-fly list. In some cases families have been preventing from boarding a plane because their toddler matched a name on the no-fly list. Here is a great cartoon from the SF Chronicle's Bad Reporter (Don Asmussen) about this. Another common example is if a credit bureau mixes you up with someone else with the same name, and all of a sudden you can't get any credit.

There is also the opposite issue of the same thing being mixed up as two different things. I experienced this myself when I couldn't get my driver's license renewed because I had registered my last name as “Van Couvering” whereas my Social Security information has my last name as “Vancouvering” (incorrect),. The computers decided I was not the same person and would not renew my license. I had to work with the Social Security office to change it before I could drive again.

So, this raises the question, when you can't rely on some guaranteed generate unique identifier, how do you identify something? What does it mean to be identical? This philosophical article refers to 'Liebniz's Law' which states that two objects are defined to be identical if and only if each and every property of the two objects are the same. But with databases you only have a certain number of properties to go by; what if all of these are the same – is it the same thing or isn't it? The answer is: you just don't know.

As more and more of our lives are controlled and driven by databases about us, and we are identified not by who we are but by properties about us, this becomes less and less a philosophical question and more and more of a real issue. A prime example of this is identity theft: if someone can obtain enough of your “properties” they can convince others that they are you. I know there are a lot of important social issues around things like biometrics and embedded RFID chips, but in this growing informational society, part of me would love to have a way to have undeniable proof that I am me and not someone else, and that someone else is not me.

On a completely different note, here's another issue around identity. If something changes over time, is it or is it not still the same thing? This is called the paradox of the Ship of Theseus

All the cells of a human being are replaced every six years. We grow older. Some people get sex change operations. Some people dye their hair. We can get cosmetic surgery. We can have organ transplants. There are no observable qualities of a person that can be guaranteed to be unique and unchanging over time. But you and I know that we are still the same person. We know this because we have the feeling: I exist, I am. It is our inner experience of identity. You and I will both say with full certainty that I am and always have been “me.”

But now I posit something to you: if the experience of “I am” is our only truly reliable measure of identity, what if my experience of “I am” is exactly the same as your experience of “I am?” Are we then identical? This odd conclusion is actually what many spiritual traditions of the East claim: that the experience of “I am” is the nature of God, and that it is identical in each person: at our core we are all the same. That doesn't help when you are trying to prove you're not on the no-fly list, but it is something to think about...