The term seems to originate in Ashby's Design for a Brain (p 41) and refers
to those internal values (and their bounds) needed in a homeostat to
maintain life. Examples incluse blood oxygen, the structural integrity of
themedulla oblongata and pain from burns. Ashby thinks these variables might
be arranged roughly in their order of importance to survival but cautions
about using the order for particular deductions.
There is a discussion of the "coenetic" aspects of this in "The Viable
System Model:its provenance, development, methodology and pathology" by
Stafford in Raul and Roger's "The Viable System Model" page 16- page 4 in
the paper which is online
But there are likely other discussions relevant e.g. The Variety Sponge in
p289 in Decision and Control. I don't feel I've quite put my finger on this
and others may have something more specific.
----- Original Message -----
From: "BARRY A CLEMSON" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, December 03, 2008 4:49 PM
Subject: Re: Essential Variables
> I believe Stafford and Ashby were totally in agreement on EV.
> I don't remember offhand where to find Stafford's discussions of EV
> but I am pretty sure both Brain and Heart talk about them.
> On Dec 3, 2008, at 11:30 AM, Arthur Dijkstra wrote:
>> Dear all,
>> I think I qualify for an S3, quoting Barry:
>> "To get anywhere with academic types, we need to work with those who
>> two criteria:
>> 1) they don't have competing approaches of their own (this rules out
>> all the
>> business schools, public administration, and educational
>> 2) they are interested in solving practical problems of great
>> My question is about Essential Variables (EV). As you know I am
>> developing a
>> safety management system based on the VSM. Safety will be nominated
>> an EV.
>> I have no direct access over all my Stafford books right now (out
>> flying on
>> layover) but I was surprised not to find EV in the index of The Heart.
>> How and where does Stafford clearly talk about EV's ? Does he agree
>> Ashby about EV's ?
>> For more information go to: www.metaphorum.org
>> For the Metaphorum Collaborative Working Environment (MCWE) go to:
>> METAPHORUM eList Archive available at -
>> Archive of CYBCOM eList available at -
> BARRY A CLEMSON
> [log in to unmask]
> Cybernetica Press at www.cyberneticapress.com
> "It's not how much you do - it's how much love you put in it.... Do
> small things with great love."
> --- Mother Teresa ---
> The true warrior may be killed, but he can not be defeated.
> --- my paraphrase of Sensei Hamada ---
> And peace rolled down like a mighty river.
> -- Inspired by the prophet Amos 5:24--
> "An enemy is a person whose story we have not heard."
> -- Gene Knudsen Hoffman --
> For more information go to: www.metaphorum.org
> For the Metaphorum Collaborative Working Environment (MCWE) go to:
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