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Guide

immanuel Kant, data modeler

Only the users can say whether a data model a human’s model of what appears to be “out there.” For ex-
accurately reflects their business environment. What hap- ample, a model of a salesperson is a model of the model that
pens when the users disagree among themselves? What if one humans make of salespeople.
user says orders have a single salesperson, but another says To return to the question that we started with, what
that sales teams produce some orders? Who is correct? do we do when people disagree about what should be in a
It’s tempting to say, “The correct model is the one that data model? First, realize that anyone attempting to justify
better represents the real world.” The problem with this state- her data model as a better representation of the real world
ment is that data models do not model “the real world.” A is saying, quite arrogantly, “The way I think of the world is
data model is simply a model of what the data modeler per-
ceives. This very important point can be difficult to under-
stand, but if you do understand it, you will save many hours
in data model validation meetings and be a much better data
modeling team member.
The German philosopher Immanuel Kant reasoned
that what we perceive as reality is based on our perceptive
apparatus. That which we perceive he called phenomena.
Our perceptions, such as of light and sound, are processed
by our brains and made meaningful. But we do not and
cannot know whether the images we create from the per-
ceptions have anything to do with what might or might not
really be.
Kant used the term noumenal world to refer to the essence
of “things in themselves”—to whatever it is out there that
gives rise to our perceptions and images. He used the term
phenomenal world to refer to what we humans perceive and
construct.
It is easy to confuse the noumenal world with the phe-
nomenal world, because we share the phenomenal world
with other humans. All of us have the same mental appara-
tus, and we all make the same constructions. If you ask your
roommate to hand you the toothpaste, she hands you the
toothpaste, not a hairbrush. But the fact that we share this
mutual view does not mean that the mutual view describes
in any way what is truly out there. Dogs construct a world
based on smells, and orca whales construct a world based on
sounds. What the “real world” is to a dog, a whale, and a hu-
man are completely different. All of this means that we can-
not ever justify a data model as a “better representation of
the real world.” Nothing that humans can do represents the
real, noumenal world. A data model, therefore, is a model of
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