[FRIAM] Re-named topic to: Mono- and bi-directionality in systems

[Glen E. P. Ropella]

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I believe the question is ill-formed.  This "directionality" of
relationships is an abstraction.  And from that perspective, yes,
directionality is purely a function of the perspective adopted by the model.

A model of a living system can be uni-directional or bi-directional.
But, I believe the living system can't be _fully_ described in those terms.

It also seems plausible that a model can be both bi- and uni-directional
if the model has multiple scales.

But, I don't think we can say with any certainty that the model's
referent (the living system) is uni-, bi-, multi-, or non-directional.
We can only say things like:

"using model X, which is uni-directional, we can predict behavior Y in
the system"

or

"model X has been validated against behavior Y in the system and model X
is uni-directional, hence (by parsimony) we posit that behavior Y in the
system is the result of a uni-directional mechanism".

Note the fulcrum:  "behavior Y".

Louis Macovsky wrote:
>>>So, I again submit that there usually (always?) is bi-directionality
> in living systems, but perhaps others will have examples where
> mono-directionality (As Robert said: " The cause-and-effect arrow of
> implication is one-way.") is the only case.<<
>  
> Isn't "mono vs. bi" directionality dependent upon model "grain" or or
> the bias of scale.   I would think all one-way causal relationships can
> become bidirectional as perspective zooms in or out.
>  
> Bidirectionality can be represented by a causal *loop* diagram where the
> cause-and-effect arrow is always one-way.  

- --
glen e. p. ropella, 971-219-3846, http://tempusdictum.com
Everything is vague to a degree you do not realize till you have tried
to make it precise. -- Bertrand Russell

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