Re: Equilibrium, stasis and death <Steve.Keen@unsw.EDU.AU>

["Alan G. Isaac" <AISAAC@xxxxxxxxxxxx>]

This might be a helpful initial taxonomy. May I replace (2), since
I do not think optimality per se has any claim to equilibrium status,
with
(2') Static: rhetorical characterizations of 'equilibrium' relying
on implicit but unmodelled background dynamic adjustment assumptions
(as in the Arrow-Debreu or static "Keynesian" models).

I still await an example of (3) that does not rely on (1) at some level.

On Wed, 19 Jan 1994 21:20:47 -0700 <Steve.Keen@xxxxxxxxxxx> said:
>A discussion which began about equilibrium has progressed to multiple
>equilibria and thence to multiple concepts of what equiibria are. There
>are at least three distinct concepts floating in this discussion:
>(1) Mechanistic: something staying in its present state in the absence
>of additional outside forces
>(2) Optimality--a situation preferred to all neighbouring situations
>to which conscious and single-motivated (?) beings move
>(3) Dynamic--a situation of relative stability which develops from
>the interactions of several coupled systems all acting under the
>influence of one or more forcing agents.
>
>My sympathies are with version (3), but this concept of equilibrium
>is quite unlike the other two. Jim Devine's comment about using
>equilibrium as a yardstick by which to measurew other situations
>largely applies to (2), for example, . To return to te example I
>lifted from the Dialetical Biologist concerning the atmosphere,
>the fact that the nitrogen/oxygen/CO2 balance is 80/20/trace and
>remarkably stable is neither (1) nor (2). It is a (3), an otherwise
>highly unstable situation maintained largely by living organisms
>in the presence of two major forcing systems: the Sun, and the
>outputs of other living organisms. It can't be studied in a
>mechanistic, non-evolutionary way: mechanistically, what happens
>when you combine Nitrogen, Oxygen and a large sum of carbon-based
>objects at a temperature of 30C--speaking from Sydney, it's
>obvious--bushfires and a CO2 dominated atmosphere! Nor is optimality
>particularly relevant: the original atmosphere was optimal to the
>anaerobic organisms which evolved, but they were wiped out when
>aerobic, carbon-fixing organisms evolved. It is optimal to us,m
>their descendants, but that has mpore to do with the vagaries of
>time than any predetermined optimality.
>Cheers,
>Steve Keen