Well, I know this is another one of my out-of-left-field questions,
but out of curiousity is gravity a constraint or a force? Does it
depend on where you measure it? What about at planetary distances?
Really I am just curious and not attempting to poke or provoke.
Thank you-
Victoria
[ ps so is my ignorance a constraint or a force, and what changes that?
On Mar 13, 2011, at 9:45 AM, Russ Abbott wrote:
Eric and Lee have nice discussions. The only thing I would add as
something of a generalization is that constraints have to do with
the structure of something--in Lee's case, the way the hand is
structured and how it's held together at the joints and in Eric's
case the structure created by the bumpers on the alley. Forces
become important when one discusses the expenditure of energy--in
Lee's case the use of energy to move the hand given the constraints
and in Eric's case the energy that imparted momentum to the ball.
One thing that makes this more difficult is that many social (and
biological) systems expend energy to maintain structure: a police
force is an example as is a government more generally. In Lee's and
Eric's examples, we imagine the structures being maintained
statically (and indefinitely) by whatever holds the pieces in place.
In social and biological organizations many of the structures would
fall apart were it not for the continual expenditure of energy.
-- Russ Abbott
_____________________________________________
Professor, Computer Science
California State University, Los Angeles
Google voice: 747-999-5105
blog: http://russabbott.blogspot.com/
vita: http://sites.google.com/site/russabbott/
_____________________________________________
On Sun, Mar 13, 2011 at 7:57 AM, ERIC P. CHARLES <e...@psu.edu> wrote:
I suspect that outside the context of a specific example, this is
not really possible to answer. Throwing your own pet distinction
back at you, we need to know what we are trying to explain, so we
can avoid slipping levels of analysis. I have not read the author in
question, but suspect an example (with slippage) would go something
like this:
Imagine a child bowling with bumpers. The child causes the ball to
roll down the lane, and to hit the pins. The bumpers constrain the
path of the ball to be in the direction of the pins. That is, the
overall path of the ball is roughly: /\/\/\/\/\/\/\/\X (our lucky
kid rolls a strike), and when asked to explain that macro-movement -
the child causes, the bumpers constrain. If that is correct, it is
going to be a big problem if we slip our level of analysis to the
details of the path of the ball. If, instead of explaining the
overall pattern, we ask about a single jag (a single \) then the
bumper has a causal roll, in that it applied force to the ball (or
redirected force applied to it by the ball). So, what we find from
our example is that all "constraints" are "causes" at another level
of analysis - which would be terribly confusing if not specified.
For a more flippant example: Does my cable TV subscription constrain
what I watch, or cause it? When I am flipping through the channels,
it constrains it. When I stay on the same channel, whatever is on,
it causes it.
Another thought: This is the same silly distinction made by people
who are not willing to commit fully to epigenetic development. They
say things like "genes create the constrains that the environment
works within." (The most obvious reason it is silly is because one
could just as easily reverse the terms.)
Hope something in that helps,
Eric
On Sun, Mar 13, 2011 01:45 AM, "Nicholas Thompson" <nickthomp...@earthlink.net
> wrote:
Dear anybody,
I am reviewing a book by a psychologist in which the author makes a
distinction between constraints and causes. Now perhaps I am over
thinking this, but this distinction seems to parallel one made by
Feynman in his famous physics text, where he defines a constraint as
a force that does no work. If I have it right, the idea goes like
this: If you place a bowling ball on a table the ball neither
receives work from gravity nor does the table do any work holding
the ball up because the ball does not move, and work is just the
movement of mass. Indeed, even if you were to slide the table out
and, with great effort, were to hold the ball in the same position
for an hour, you wouldn’t be doing any work, either. Similarly, in
a ball rolling down an inclined plane, the plane itself does no work
because even tho it affects the motion of the ball, its effect is
always perpendicular to the motion of the ball and there fore
affects its motion neither one way or the either …. i.e., does no
work!
Now I would leave it at that except that Alicia Juarrero in her book
also makes a huge distinction between forces and constraints, one
which I think our own Steve Guerin applauds. It is the constraints
that make it possible for far-from-equilibrium systems to self
organize and do work. Perhaps I can make this work with Feynman’s
definition if I think about the dam beside a water wheel, and the
water wheel itself, as applying constraints to the water (they do no
work themselves) which make it possible for the falling water to do
work. Am I still on track, here?
Now Juarrero goes on to make a distinction between between context
sensitive and context-free. I have read these passages dozens of
times and I just don’t understand this distinction. Can anybody out
there explain it to me as to a Very Small Child.
Thanks,
Nick
Nicholas S. Thompson
Emeritus Professor of Psychology and Biology
Clark University
http://home.earthlink.net/~nickthompson/naturaldesigns/
http://www.cusf.org
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Eric Charles
Professional Student and
Assistant Professor of Psychology
Penn State University
Altoona, PA 16601
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============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
============================================================
FRIAM Applied Complexity Group listserv
Meets Fridays 9a-11:30 at cafe at St. John's College
lectures, archives, unsubscribe, maps at http://www.friam.org
