Re: Trying to define Surrogates

erk wrote:
> 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 he does. It's obvious in hindsight, erk - one can of campbells will be in your left hand and one in yourright. You distinguish them by their unique positions in space. Now, thats hardly an attribute we can easily keep track of, so the artificial id acts as a surrogate for it.

> , 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
Received on Thu Aug 17 2006 - 18:17:23 CEST