Inequivalence of models

[Steve Johnson <***>]

According to Rosen's view of complexity a system must
possess inequivalent models in order to be complex.

This seems to make intuitive sense but I cannot seem
to figure out what it would mean in practice. Where
does one model end and the other begin? How do we test
models for non-equivalence?

For example, let's take a car. It has a mechanical
blueprint that tells where the wheels attach to the
transmission, how the engine is attached to the shaft
etc. The car also has a diagram of its electric wiring
which is quite different from the mechanic blueprint.

Each of these "models" (mechanical and electric) will
allow us to formulate hypothesis about the car. So it
seems that the Modelling Relation commutes.

I would assume that the car is a simple system at
least as far as its car-ness (or form) is concerned.
So according to Rosen we should have all its models
reducible to one largest one. I confess that while I
think I grasp his mathematical argument in Life Itself
I have no idea what that means in practice. 

So here are my questions:

1) Are these two models of the car(mechanical and
electric) really one model? Why or why not? What is
the criteria that allow us to say that they are two
different models.

2) If they are different models, what is the largest
model that subsumes them? How would one go about
constructing it?

Thanks,

- Steve





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