Re: Trying to define Surrogates

JOG wrote:
> are you telling me that two Cans of Campbell's have no identity without
> an artificial label? If that were true you would not be able to
> distinguish them, yet you can. What, then, is that distinguishing
> property?

That's a deep philosophical issue for William Kent to answer, and one which depends critically on formal definitions of "identity", "same", "equivalent", "equality", "distinguish," etc. Whether you assign a number (which may or may not be printed on the can), or an RFID, a database has no way to distinguish them unless you give it that artifical label. I agree the cans are distinct in the real world, and have identity. It makes no real difference for most of the data we care about. If I spill the pyramid of cans, and hand you an undented one, will you be able to determine whether it's the one you were eyeballing before I knocked them down? So when physical location changes, and you don't track it explicitly, identity is lost - still there, but unknown to us.

A database is not the real world. Since a database concerns known facts, the limits of our knowledge (e.g. whether you can know which of the nearly-identical cans you want) are direcly reflected in our ability to design and maintain a database.  

• erk