Re: [FRIAM] Assistance sought: The meaning of constraints

[lrudolph]

[my comment follows Russ's]

Russ Abbot writes:
 
> As I understand it, work is defined as the change in kinetic energy
> resulting from the application of a force. Normally that means work is force
> times distance. So if there is no distance (no motion) there is no change in
> kinetic energy and hence no work.  A tug-of-war between two absolutely
> balanced teams results in no work even though both sides are pulling as hard
> as they can. But is that what you are really interested in? That gets us
> somewhat far afield from a more general notion of constraint. Perhaps it
> would be helpful if you would clarify what you care about in this context.

In what it is that Nick cares about, is there *any*
reason to believe that there is *any* "conservation
principle" for *anything* (in his system[s] of
interest) that plays a role like that of "energy"?
Only if there is such a principle, it seems to me,
is there any principled way for him (or you or us
or me) to distinguish some analogues of "kinetic 
energy" and "potential energy"; and (again, as it
seems to me) without an analogue of "kinetic 
energy" (principled or not), the definition of 
"work" from physics (that you quote above) begins
to drift into inanaloguizability even before we
tax it by asking "what's 'force' in Nick's context?" 
(already under discussion), much less "what's 
distance/motion in Nick's context?" (only recently 
mooted).  

Lee Rudolph


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

Re: [FRIAM] Assistance sought: The meaning of constraints

[Nicholas Thompson]

Interesting.  I need to reread the other suggestions, but I think it's a New
Thought.

Thanks, 

Nick 

-Original Message-
From: friam-boun...@redfish.com [mailto:friam-boun...@redfish.com] On Behalf
Of Sarbajit Roy
Sent: Sunday, March 13, 2011 1:21 AM
To: The Friday Morning Applied Complexity Coffee Group
Subject: Re: [FRIAM] Assistance sought: The meaning of constraints

Babytalk:

A constraint is a "limit". There are forces (smacks on your bottom ?
electric shocks ?) you shall experience which keep you within those limits
or to push you back if you stray outside.

On 3/13/11, Nicholas  Thompson  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 <http://www.cusf.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



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

Re: [FRIAM] Assistance sought: The meaning of constraints

[ERIC P. CHARLES]

Trying to stay consistent about my levels-of-analysis point:
If you are trying to escape orbit in a rocket, then gravity is a constraint.

If you are trying to explain why your head hit the floor after your foot caught
on a rock, then gravity is a cause. 

Eric

On Sun, Mar 13, 2011 05:31 PM, Victoria Hughes  wrote:
>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: 
>   vita:  
>_ 
>
>
>
>
>
>
>>On Sun, Mar 13, 2011 at 7:57 AM, ERIC P. CHARLES <<#>> 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" <<#>> 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 t

Re: [FRIAM] Assistance sought: The meaning of constraints

[lrudolph]

On 13 Mar 2011 at 15:31, Victoria Hughes wrote:

> 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?

On Newton's account of things (if not in his language?)
it's a force; I think also in Special Relativity.
In General Relativity, I think I ought to say it's
a constraint, but I don't know what Real Physicists
say.  Some witty physicist (John Archibald Wheeler,
if Google can be trusted) put it nicely as "Matter 
tells space how to curve, and space tells matter 
how to move." Force being, more or less by definition, 
what "tells matter how to move" (more precisely and 
correctly: how to *change* how it is moving), here 
we see gravity in its avatar as the shape of space: 
which sure seems to me like it should be called a 
constraint.

I have no idea what the Einstein's "gravitational
constant" (that the cosmologists claim is not actually,
you know, *constant*) means for this style of 
explanation. 

> 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  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" 
> >  > > wrote:
> > Dear anybody,
> >
> >
> >
> >
> >
> >
> > I am reviewing a book by a psychologist in which the author makes a  
> > distinction between constraints and causes.   Now p

Re: [FRIAM] Assistance sought: The meaning of constraints

[Victoria Hughes]

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  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" > 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 sy

Re: [FRIAM] Assistance sought: The meaning of constraints

[Russ Abbott]

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  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 b

Re: [FRIAM] Assistance sought: The meaning of constraints

[ERIC P. CHARLES]

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"
 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. 


>
>


>
>


>
>
>


>
> 


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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
>

Eric Charles

Professional Student and
Assistant Professor of Psychology
Penn State University
Altoona, PA 16601



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

Re: [FRIAM] Assistance sought: The meaning of constraints

[lrudolph]

Dear Nick,

I am also reviewing a book--actually, two booklets 
and a book chapter--in the sense that I am working 
mightily to incorporate into a book I am editing 
and partly writing (on mathematical models for use 
in psychology) a discussion of their virtues
and vices.  In my case, the matter being reviewed is
not by a psychologist but by a historian, Henry Adams.  
Adams spent much of his life trying (and conspicuously 
failing) to do what *I* would call making a mathematical
model of history, though he only occasionally spoke of
mathematics and mathematicians and much more often 
of physics and physicists (19th century in all cases).
Sometimes (as in the booklets "A Letter to American 
Teachers of History" and "The Rule of Phase as Applied
to History") he tried to adapt thermodynamics to his
purposes; at other times (as in _The Education of 
Henry Adams_, particularly the chapter "The Dynamo
and the Virgin") he talked in terms of "dynamics"
more generally.

His failure to get anywhere at all (as I see it) 
started with his (predictable?) failure to make any
sense *at all* of "forces" in his context.

I would (not only, but largely, therefore) caution
you, Nick, against importing any notion of "force"
into your explication of your psychologist's "distinction
between constraints and causes"; "forces" are not needed
to explicate "constraints" (or "causes") as far as I'm
concerned, and they carry an awful lot of misleading
and potentially destructive "excess meaning" (to use
your term).

So, then, what are constraints in my lexicon (that of
a mathematical modeler who is enlightened to the extent
that physics is *not* taken as the unique, or prefered,
domain for models and model-prototypes)?  _The constraints
on a particular system are whatever specifies it among
all systems of the same general type._  Of course, all
the nouns and adjectives in that last sentence are open
to contentious negotiation: what's a "system"? what's
the "type" of a system, what do "particular" and 
"general" and "same" mean? what (even) does "all"
mean? I hope we don't have to go all the way there.

Here is an example (drawn from theoretical robotics, not 
from psychology or history).  A "robot hand" can be 
mathematically modeled (to a first, but useful, 
approximation) as a system of line segments (the 
bones of the fingers and thumbs) located in ordinary
3D space.  To model a hand at all, those line segments
need to meet up in certain ways (e.g., the segments
that represent the bones of a single phalange have to
form a "chain" in which successive segments have one
endpoint--a joint--in common).  To model a humanoid hand, 
the line segments have to be appropriately limited in 
number (e.g., if "-oid" is taken fairly strictly, not
too many to a chain, and not too many chains altogether),
and their "degrees of freedom" have to be specified
as well (e.g., the inter-segment joints are R joints,
with one degree of angular freedom; maybe there's a
"thumb" with an S joint, having two degrees of angular
freedom, at one of its two loose ends; the lengths of
the line segments should be specified, at least by
giving a range of possible lengths).  

Everything in the last paragraph after "3D space" 
could be read as giving (some of) those "constraints" 
on a (general) "linkage system" that make it a 
"robot hand linkage system", if one's focus of interest
were so wide that it included both general linkage
systems and robot hand linkage systems.  On the other
hand, if one's focus narrows only to "robot hand
linkage systems", then you might not want to call
*those* descriptors "constraints"; rather, within
the universe-of-discourse that covers only "robot
hand linkage systems", the constraints would be
(in part) *specific* lengths for joints, *specific*
range restrictions on the angular degrees of freedom,
and (if you want to make life hard for yourself) 
further specifications, for instance, the requirement
that segments cannot pass through each other during
any motion of the system.

There are no forces in sight.  One way to "explain"
their absence is to say that what has been described, 
so far,is a "kinematics" model of the robot hand; and 
that, if you want to actually be an engineer and make 
(or plan to make) a physical robot hand, you will have 
to put in some physics--meaning (here) forces (as well 
as materials specifications [which could, reductively,
be phrased exclusively in terms of forces: but with 
a huge expansion in verbiage and diminution in human
understandability])--and then do "dynamics".  Some of
the dynamics you do will explain, retrospectively, 
why you can successfully ignore the "forces" in the
kinematics model: they are "doing no work".  

In the psychological case, where you-all already are 
(if I've been following) in a quandary as to what,
if anything, plays the role in a satisfactory
description of "causes" of feelings that is
analogous to "force" in a satisfactory description
of "causes" of motions of billiar

Re: [FRIAM] Assistance sought: The meaning of constraints

[Sarbajit Roy]

Babytalk:

A constraint is a "limit". There are forces (smacks on your bottom ?
electric shocks ?) you shall experience which keep you within those
limits or to push you back if you stray outside.

On 3/13/11, Nicholas  Thompson  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 
>
>
>
>
>
>


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] Assistance sought: The meaning of constraints

[Nicholas Thompson]

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  

 

 


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