Re: some ideas about db rheory

From: rpost <>
Date: Mon, 10 Aug 2009 17:09:21 +0000 (UTC)
Message-ID: <h5pk81$fm9$>

Brian wrote:

>On Jul 27, 7:46 pm, rp_at_raampje.(none) (Reinier Post) wrote:
>> I wrote:
>> >> [...] if you have no way to track identity across changes
>> >> in real life, adding it as a modeling feature (either with explicit
>> >> identities or by distinguishing between updates and deletes+inserts,
>> >> as Brian proposes) isn't going to help a bit.
>> Brian replies:
>> >[...]   Either there can be change, which implies that there can be
>> >things that can change, or there cannot be change, which means that
>> >there cannot be deletes or inserts, let alone updates.
>> No, Brian.  These deletes, inserts, and updates are about statements
>> of fact about the world, which can change to reflect new or changed
>> observations, even when we haven't identified any objects that these
>> statements are about to the extent you appear to deem necessary.  I can
>> observe Mary's goldfish and its medical condition, and truthfully record
>> that in my database, two days in a row, *regardless of* whether I can
>> tell whether we're dealing with the same goldfish in both cases.
>Either there can be change, which implies that there can be things
>that can change, [...]

Yes, there can be change, and there can be things that can change. I am not Parmenides. (Although Parmenides would doubt that.)

>Your argument neither affirms or denies my statement. What it does is
>illustrate the fact that descriptions, such as "Mary's goldfish," can
>refer to different things at different times in the same way that a
>particular instance of a composite key can refer to different things
>at different times--something I've been arguing for a long time.

I completely agree. But what does it mean to say that they are different things? My claim is that what it means you have a *different* model in your mind in which the same thing is represented only once. In other words, you are essentially comparing two different models of the same reality, rather than comparing a model to 'reality itself', something other than a model. This is the mistake pretty much everybody I've ever been pointed to regarding the issue of identity appears to make: they don't realize it's essentially a language feature, and relative to the conceptual model you're using, even if that model is incomplete or informal.

>Because interpreters are temporal beings, interpretations must occur /
>at a time/, which requires that there must be different
>interpretations at different times. Even under the possible worlds
>paradigm, only one possible world at a time can be the actual world.

Only if you make it so by definition of what a possible world is.


>[...] If there can be things that
>can change, but the system has no way to track identity across
>changes, then the system is broken.

Not if you don't care about that identity. And we need to settle for compromises if we are ever going to settle on a finite conceptual model of anything.


>Statements are /always/ about things. Each term in a statement is
>assigned something--some...thing--under an interpretation.

Mathematicians traditionally define things that way, but that doesn't make it true. If you stick with it, and fail to recognizing that identity is a feature in a modeling language used to describe the world, rather than the world itself, how are you ever going to get rid of those famous 'logical paradoxes' related to identity?

Received on Mon Aug 10 2009 - 19:09:21 CEST

Original text of this message