John's earlier point was that a model gets
some aspect of the
world right. That, as Chris says, is what makes it useful. I think the
problem is that 'approximation' is a poor word for the relationship of
the model to the thing/world. The model accurately renders
some
subset of the properties of the thing/world.
I am, however, reminded of a colleague's long-standing email tag
quotation:
"A theory has only the alternative of being right or wrong. A
model has a third possibility: it may be right but irrelevant."
-- Manfred Eigen
But that really says only that a model has a purpose. The subset of
properties of the thing/world that it captures must be the "right"
subset for that purpose, and any other subset is useless for the
purpose. Deming's "all models are wrong" simply admits that a model
intentionally misrenders aspects not relevant to the purpose. And a
formal logic "model" simply omits them.
-Ed
--
Edward J. Barkmeyer Email: edbark@xxxxxxxx
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Stop 8263 Tel: +1 301-975-3528
Gaithersburg, MD 20899-8263 Cel: +1 240-672-5800
"The opinions expressed above do not reflect consensus of NIST,
and have not been reviewed by any Government authority."