Re: Modelling Considered Harmful

mAsterdam wrote:
> Kenneth Downs wrote:
> > I wonder if anybody would care to dispute the thesis that use of
the term
> > "modelling" with regard to databases does more harm than good.
>
> Yes, it is a good excercise. I allready commented in some
> sub-threads, but you dismissed my remarks. I think there is more to
> this, so I chose to reply to the OP this time.
>
> Let's dissect :-)
>
> > The case can also be stated that databases are NOT models of
reality.
>
> They are not, agreed.
>
> > They are rather record-keeping systems.
>
> Yep.
>
> > If it can be shown that databases are
> > record-keeping, that record-keeping is not modelling, then it
stands that
> > we would not call databases models.
>
> So far, so good.
>
> > We need to define models and records.
>
> Do we really? Language is as language does. Language is not a
> record-keeper (database), nor is it a model.

Language is used to model thoughts. I cannot beam my thoughts into your brain, but I can model the thoughts using language and then you can use that to try to get a handle on what I am really thinking. So, language is a modeling tool, right?

> But, if you insist ...
> my take is definitons may or may not be helpful in judging wether
> the term "modelling" is harmful or not, but I'm willing to come
along.
>
> > Leaving out the silly definitions
> > like a person posing for a picture some useful definitions of model
are:
>
> (nothing silly about that, as I said earlier)

agreed. A fashion model does, in fact, model.

> > 1. A miniature representation of a thing
> > 2. Something intended to serve, as a pattern of something to be
made
> > 3. Anything which serves, or may serve, as an example for
imitation
> > 4. Any copy, or resemblance, more or less exact.
>
> Nah. Suggested replacement: simplified repesentation to study some
> aspects. Think chemical model, simcity, prototypes, windtunnel,
> Bohr's atom, Marx's (&Ricardo's) capitalism, the nude on the sofa.
>
> > 5. An abstract and often simplified conceptual representation
> > of the workings of a system of objects in the real world
>
> Hm... no purpose. Ok, forget 4 and provide 5 and 6 with a purpose.

While it is a good idea to model for a purpose, I don't think that is essential to the definition of the model. Instead one might write "we are using a model to ...". If I'm working with Lincoln Logs (which might be differently named outside the US), my purpose might be "play" or even "beauty" or as a creative act. The modeling need not be for the purpose of studying something except perhaps in the very broadest terms.

> > 6. a simplified description of a complex entity or process
> >
> > For "record", we leave out things like a 12" disc of vinyl, and we
get some
> > nice stuff. I like this first one out of Webster's for the verb
record:
> >
> > To preserve the memory of, by committing to writing, to
> > printing, to inscription, or the like; to make note of; to
> > write or enter in a book or on parchment, for the purpose
> > of preserving authentic evidence of; to register; to
> > enroll; as, to record the proceedings of a court; to
> > record historical events
> >
> > Here is the noun version:
> >
> > A writing by which some act or event, or a number of acts
> > or events, is recorded; a register; as, a record of the
> > acts of the Hebrew kings; a record of the variations of
> > temperature during a certain time; a family record.
> >
> > Others:
> >
> > 1. That which serves to perpetuate a knowledge of acts or events;
> > 2. anything (such as a document or a phonograph record or a
> > photograph) providing permanent evidence of or
> > information about past event
>
> Nice going. Still with you, here. Suggested addition:
> 3. Form restricted registration of ... hm... of what? facts? That
> would leave out simulations, ok :
> 3. Form restricted registration of propositions.
>
> > It should seem almost painfully obvious that the standard examples
of
> > employees, sales orders, inventory activity and so forth fit far
more the
> > definitions for "records" than they do for "model".

They fit both because records, themselves, are modeling something.

> Both. Appearantly employees, sales orders, inventory activity and so
> forth are so common, that they serve as parts of the model we use to
> describe our day to day record-keeping problems in the abstract, i.e
> without having to resort to a specific business. Them being standard
> examples make them part of that aspect-model.
>
> > One could stretch a
> > point and contend that a sales order fits the definition of model
because
> > it is "Something intended to serve, as a pattern of something to be
made",
> > but really it is just instructions.
>
> Generalized instructions, though. 'just instructions' would suggest
> _specific_ instructions, not usable for anything but the topic at
> hand. That's where (useful use of) the term 'model' comes in.
>
> > Taking the other side, if you are using a database to do a huge
weather
> > simulation, then we argue that the application is modelling
reality,
>
> We? I would argue it models some aspects of reality, nothing more.

agreed.

> > but actually this is not so either.
> > The tables cannot run the simulation, they
> > can only record the results of some other program doing so. Though
the
> > records are the records of a model, they are still records, and are
not
> > themselves a model.

They model something and are, therefore, models.

> Ok.
>
> > So where is the harm? Well, there is always a problem when you
call a car a
> > horse, because you risk stuffing hay down the gas pipe and you can
really
> > scratch the finish with those brushes.

It is definitely the case that language changes our interpretations of the world around us. Because language models reality, rather than BEING reality, it is a simplification. If we simplify by removing female pronous from our writing or having only one word for snow, rather than 5, we do affect the way people think. So, I definitely agree that the way we model our thoughts using language is very important. The way we model our data using various mathematical constructs is also very important to how we think of this data and of our work.

> Any attempt to advance the theory
> > of databases should understand them for what they are, or the
theory will
> > go off in the wrong direction.

Yes, agreed.

> 'Calling a car a horse' is a mistake made often indeed. The nice
> thing about modelling is to make these acquired preconceptions (no
> this is not a contradictio in terminis, please think about it)
> explicit so we can see the differences between a car and a horse.

agreed

> > Nor is the meta-data a model.

of course it is!

> Indeed. It's just the record-keeping of the record-keeping
> mechanism - registering the forms.

So, it is a model about the model.

> > The meta-data for the employees table does
> > not model the company, it specifies what information must be
recorded to
> > conform with law and policy. since meta-data is data, the
meta-data is a
> > record of what must be recorded. Still no model.
> >
> > Agree? Disagree?
>
> I see benefits in using the term 'model' appropriately.

I think the term "model" is central to all software development. That is what we do from start to finish and also what we produce. It is both the process and object of our work. So, I'm definitely not with you on this one!

Cheers! --dawn Received on Wed May 04 2005 - 19:06:21 CEST