From[Bill Williams 19 March 2004 7:00 PM CST]
Bruce Abbott, and Bill Powers,
Last night I wrote out a two or three page draft on the [I=S] identity. I
didn't send it this morning or today because I wanted to re-read it first.
And, there was a seminar today that looked as if it might turn into
something that might end the program here. As it turned out nothing like
what I expected happened but it was a sweaty anxious time.
I'm am going to get out of here for a while, but I will see what I can do.
I don't ordinarily have an audience outside the department-- so this might
be interesting.
As a preliminary indication of where my thinking is in this matter-- in the
appendix to _BCP_ Bill Powers describes two ways of thinking about what
happens in or through a control loop. Bill recommends against attempting to
follow the control process sequentially. Rather he suggests that what I
will call a simultaneous equation presentation of time rates-- one of the
difficulties may be a lack of treatments or a lexicon of terms to use in
describing the problem.
When I first got a copy of BCP one of the first things I did was look at the
appendix and see how time was being handled. Powers' treatment was the
first time that I had seen "time" being treated (at least in psychology) in
a way that I thought was correct. As I read Bruin's dissertation the
treatment of time seems to be OK, but rather clumsy.
One of the things that came up in the seminar today was the issue of time
and equations. Everyone thought there was a logical necessity that time had
to be treated in a period sequence configuration. Everyone except me that
is so I have in addition to the two of you an at least potential audience in
the department.
I'm not sure when I will have a draft, but sometime this weekend
Bill Williams
ยทยทยท
----- Original Message -----
From: "Bruce Abbott" <abbott@IPFW.EDU>
To: <CSGNET@listserv.uiuc.edu>
Sent: Friday, March 19, 2004 2:55 PM
Subject: Re: PCT and the Police
[From Bruce Abbott (2004.03.19.1555 EST)]
>[From Bill Powers (2004.03.19.1215 MST)]
>
>>[From Bill Williams 18 March 2004 2:50 AM CST]
>
>I still would like to know how it is that money saved is equal to money
>invested, or whatever the correct terminology is (I would like to know
what
>the correct terminology is, too). I was unable to follow Keynes'
derivation
>of that conclusion, since he just seemed to assume it, and then rewrote
the
>same assumption in the form of a conclusion. But I probably misunderstood
>how he arrived at his result, and so would appreciate learning what he
>actually did.May I second that request? My total exposure to economics came from
Samuelson's textbook about a million years ago when I was an undergrad and
about all I remember of that are the supply and demand curves. I don't
have a clue why Bill W. says that there is no such thing as profit (unless
the confusion has to do with distinguishing aggregate profit from the
profit realized by individuals).On a related note, I'm not at all sure that it is a good idea to apply PCT
principles to aggregate economic data. Although individuals may be
successfully modeled as hierarchies of control systems, it is unlikely
that
the "aggregate producer/consumer" is so organized. A better approach, it
seems to me, would be to construct models of individuals participating in
an economy and then see how well their aggregate behavior matches
aggregate
data. This would be a difficult task, as one would have to design a
variety of individuals who may be controlling different variables, or the
same variables at different reference levels, and then study how different
mixtures of such individuals behave as a group as various disturbances are
applied to the controlled variables. Unless one had real data available
on
which to base these decisions, the whole project would be in danger of
degenerating into an exercise in curve fitting.Bruce A.