Kenneth J. W. Craik on equilibrium and stability

[From Bruce Abbott (2017.11.13.1210 EST)]

Continuing my series of posts on Kenneth J. W. Craik’s unfinished book, The Mechanism of Human Action, Craik has this to say about equilibrium and stability:

Living organisms, as has been remarked by Herbert Spencer and later by Pavlov and many others, are in a state of dynamic equilibrium with their environments. If they do not maintain this equilibrium they die; if they do maintain it they show a degree of spontaneity, variability, and purposiveness of response unknown in the non-living world. This is what is meant by ‘adaptation to environment’. Before we review the main result of analytical study of the structure and behaviour of living organisms, let us consider from first principles—synthetically as it were—the essential features which any device must possess in order to show this type of dynamic equilibrium.

The essential feature of equilibrium is stability—that is, the ability to withstand disturbances. Some objects, such as stones, have great apparent stability, because they are so refractory that very few of the forces which they encounter are able to make any impression on them; but if they do encounter a sufficiently great disturbance they break up passively. This is a static type of equilibrium.

Other objects, such as the sea, or a steel spring, yield under an applied disturbance, but tend to return to their previous state after the disturbance has passed, by virtue of the potential energy which they have stored up while the disturbance lasted.

The third, and dynamic, type of equilibrium is that where energy derived from some outside source is utilized by the object to counter the disturbances which it encounters. For example, if you push someone, they put out one of their feet and push against the floor, so using energy derived from the food they have eaten to counter the disturbance which you caused. This device of using energy derived from outside to restore equilibrium is, I think, one of the first and most important features of living organisms to appear, and is more characteristic of dynamic equilibria than the mere fact that the rate of anabolism and catabolism are equal. Thus, the often quoted example of dynamic equilibrium—the level of water in a river—fails to emphasize this important feature: the use of external energy to restore equilibrium, even while the disturbing cause is still acting. One of the reasons why this device is so important is that it opens, to living organisms, an immense realm of possible reactions which, if it were not for the external supply of energy, would be thermodynamically ‘uphill’ and therefore unable to occur. To take an extreme case, no bird or machine could fly but for the supply of energy from outside. If it were not for living organisms the course of the world would be limited almost entirely to the steady downhill degradation of energy from its potential state in the sun and stars to its kinetic state in the thermal agitation of matter. Living organisms were, with very few exceptions, the first devices to use a downhill reaction—such as the combustion of carbohydrates—to provide them with a store of energy by which to drive a few uphill reactions for their own benefit. This does not, of course, imply that living organisms run contrary to the second law of thermodynamics and can prevent the gradual degradation of energy; it merely means that they have means of storing external energy in potential form for driving some local uphill reaction. If we consider the whole picture, the reaction is, as far as we know, always downhill on the average; but some parts of it may go uphill by virtue of the energy derived from the other parts.

Sherwood, Stephen L. (Ed.). (1966). The nature of psychology: A selection of papers, essays, and other writings by the late Kenneth J. W. Craik. London: Cambridge. Pp 13-14.

Bruce

[From Rick Marken (2017.12.13.1010)]

···

Bruce Abbott (2017.11.13.1210 EST)

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BA: Continuing my series of posts on Kenneth J. W. Craik’s unfinished book, The Mechanism of Human Action, Craik has this to say about equilibrium and stability:

 …Â

KJWC: The third, and dynamic, type of equilibrium is that where energy derived from some outside source is utilized by the object to counter the disturbances which it encounters. For example, if you push someone, they put out one of their feet and push against the floor, so using energy derived from the food they have eaten to counter the disturbance which you caused. This device of using energy derived from outside to restore equilibrium is, I think, one of the first and most important features of living organisms to appear, and is more characteristic of dynamic equilibria than the mere fact that the rate of anabolism and catabolism are equal. Thus, the often quoted example of dynamic equilibrium—the level of water in a river—fails to emphasize this important feature: the use of external energy to restore equilibrium, even while the disturbing cause is still acting. One of the reasons why this device is so important is that it opens, to living organisms, an immense realm of possible reactions which, if it were not for the external supply of energy, would be thermodynamically ‘uphill’ and therefore unable to occur. To take an extreme case, no bird or machine could fly but for the supply of energy from outside. If it were not for living organisms the course of the world would be limited almost entirely to the steady downhill degradation of energy from its potential state in the sun and stars to its kinetic state in the thermal agitation of matter. Living organisms were, with very few exceptions, the first devices to use a downhill reaction—such as the combustion of carbohydrates—to provideide them with a store of energy by which to drive a few uphill reactions for their own benefit. This does not, of course, imply that living organisms run contrary to the second law of thermodynamics and can prevent the gradual degradation of energy; it merely means that they have means of storing external energy in potential form for driving some local uphill reaction. If we consider the whole picture, the reaction is, as far as we know, always downhill on the average; but some parts of it may go uphill by virtue of the energy derived from the other parts.Â

RM: Craik is getting close here. But because he is focused on the idea of “equilibrium” he doesn’t get to see what is important about energetic disturbance resistance: the fact that variables are maintained in constant or varying reference states. I think it is these reference states of variables are what Craik refers to as equilibria. But that term doesn’t really capture what is going on, which is that variable aspects of the external (or internal) environment of organisms are being kept under control. And, of course, this kept him from noticing what Powers saw about these controlled variables: that they are what we typically refer to as the behavior of the organism, what the organism is “doing”. This prevented him from applying control theory correctly to behavior; that is, seeing that control theory had to explain why and how these variables are kept under control. If he had seen it this way – the way Powers saw it – then her would have realized that these variables are kept in reference states because organisms can perceive these variables and they have internal specifications (reference signal) for the these perceptions and that differences between internal reference and perception drive the energetic outputs that keep protect these variables from disturbance and keep them in their specified (constant or variable) reference states. So Craik was close but, unfortunately, no cigar.Â

BestÂ

RickÂ


Richard S. MarkenÂ

"Perfection is achieved not when you have nothing more to add, but when you
have nothing left to take away.�
                --Antoine de Saint-Exupery

[From Bruce Abbott (2017.12.13.1650 EST)]

[From Rick Marken (2017.12.13.1010)]

Bruce Abbott (2017.11.13.1210 EST)

BA: Continuing my series of posts on Kenneth J. W. Craik’s unfinished book, The Mechanism of Human Action, Craik has this to say about equilibrium and stability:

KJWC: The third, and dynamic, type of equilibrium is that where energy derived from some outside source is utilized by the object to counter the disturbances which it encounters. For example, if you push someone, they put out one of their feet and push against the floor, so using energy derived from the food they have eaten to counter the disturbance which you caused. This device of using energy derived from outside to restore equilibrium is, I think, one of the first and most important features of living organisms to appear, and is more characteristic of dynamic equilibria than the mere fact that the rate of anabolism and catabolism are equal. Thus, the often quoted example of dynamic equilibrium—”the level of water in a river—fails to emphasize this important feaature: the use of external energy to restore equilibrium, even while the disturbing cause is still acting. One of the reasons why this device is so important is that it opens, to living organisms, an immense realm of possible reactions which, if it were not for the external supply of energy, would be thermodynamically ‘uphill’ and therefore unable to occur. To take an extreme case, no bird or machine could fly but for the supply of energy from outside. If it were not for living organisms the course of the world would be limited almost entirely to the steady downhill degradation of energy from its potential state in the sun and stars to its kinetic state in the thermal agitation of matter. Living organisms were, with very few exceptions, the first devices to use a downhill reaction—such as the combustion of carbohydrates—to provide th them with a store of energy by which to drive a few uphill reactions for their own benefit. This does not, of course, imply that living organisms run contrary to the second law of thermodynamics and can prevent the gradual degradation of energy; it merely means that they have means of storing external energy in potential form for driving some local uphill reaction. If we consider the whole picture, the reaction is, as far as we know, always downhill on the average; but some parts of it may go uphill by virtue of the energy derived from the other parts.

RM: Craik is getting close here. But because he is focused on the idea of “equilibrium” he doesn’t get to see what is important about energetic disturbance resistance: the fact that variables are maintained in constant or varying reference states. I think it is these reference states of variables are what Craik refers to as equilibria.

KJWC: “Further, machines like automatic regulators and servo-mechanisms show behavior which is determined not just by the external disturbance acting on them and their internal store of energy, but by the relation between their disturbed state and some assigned state of equilibrium, for example, by the departure from the correct temperature which has occurred.â€? – K. J. M. Craik

Cleaarly, Craik is talking about the departure of a controlled variable from its reference value, in this case the “correct temperature. If the disturbance is constant, the system will develop an equilibrium state in which the controlled variable is maintained in a state close to its “correct� (reference) value and the output’s effect on the CV opposes and is nearly equal to the effect of the disturbance on the controlled variable.

But that term doesn’t really capture what is going on, which is that variable aspects of the external (or internal) environment of organisms are being kept under control.

Craik was familiar with negative feedback regulators and servo-mechanisms (in fact he built some), was quite aware that these control systems require sensors to monitor the current states of their controlled variables, and understood that the effectors for such systems produce outputs that actively oppose the effects of disturbances to those same variables. Regulators are designed to hold some sensed variable constant against disturbances; servo-mechanisms have variable references and are designed to produce changes in the sensed variable that track the changes in reference value. (Power steering is a familiar example, in which the angle of the front wheels of the car is made to track changes in the angle of the steering wheel.)Â

And, of course, this kept him from noticing what Powers saw about these controlled variables: that they are what we typically refer to as the behavior of the organism, what the organism is “doingâ€?. This prevented him from applying control theory correctly to behavior; that is, seeing that control theory had to explain why and how these variables are kept under control. If he had seen it this way – thee way Powers saw it – then her would have realized that these variabbles are kept in reference states because organisms can perceive these variables and they have internal specifications (reference signal) for the these perceptions and that differences between internal reference and perception drive the energetic outputs that keep protect these variables from disturbance and keep them in their specified (constant or variable) reference states. So Craik was close but, unfortunately, no cigar.

That’s quite an assertion to make, coming from one who has not read Craik’s book. That being the case, you do not know what Craik noticed or understood or realized about controlled variables and their functioning in organisms, and therefore have no legitimate basis on which to make this claim. But really, what difference would it make if Craik had seen what Powers saw about these controlled variables?  Craik’s untimely death in 1945 at age 31 prevented him from continuing this line of theory and research, leaving the field open for Powers’ later development of PCT.

Bruce

[From Rick Marken (2017.12.13.1550)]

···

Bruce Abbott (2017.12.13.1650 EST)

RM: Craik is getting close here. But because he is focused on the idea of “equilibrium” he doesn’t get to see what is important about energetic disturbance resistance: the fact that variables are maintained in constant or varying reference states. I think it is these reference states of variables are what Craik refers to as equilibria.

KJWC: “Further, machines like automatic regulators and servo-mechanisms show behavior which is determined not just by the external disturbance acting on them and their internal store of energy, but by the relation between their disturbed state and some assigned state of equilibrium, for example, by the departure from the correct temperature which has occurred.â€? – K. J. M. Craik

BA: Clearly, Craik is talking about the departure of a controlled variable from its reference value, in this case the “correct temperature.Â

 RM: Yes, indeed.

BA: Craik was familiar with negative feedback regulators and servo-mechanisms (in fact he built some), was quite aware that these control systems require sensors to monitor the current states of their controlled variables, and understood that the effectors for such systems produce outputs that actively oppose the effects of disturbances to those same variables. Â

RM: Yes, he did understand that. He is definitely one of the founders of the application of control theory to behavior called manual control theory. A good overview of this field can be found in the book "
Control theory for humans: Quantitative approaches to modeling performance byÂ

Jagacinski and Flach (NJ: Erlbaum, 2002), which I wrote a review of here:Â http://www.mindreadings.com/BookReview.htm. Indeed, Chapter 5 in LCS III is the Powers’ Control Theory (PCT) response to the manual control theory model of “adaptive” control. It is the result of a long interchange between Powers and Flach that I followed along on (and wrote some of the simulations). Flach never accepted the PCT explanation of certain types of apparently “adaptive” control, proving that you can understand control theory rather well (Flach knows control theory very well; he is an excellent mathematician and Bill had to learn (or re-learn) to do Laplace transforms – the way the behavior of a control system is represented in engineering and manual control theoiy --Â in order to communicate with him) and still not understand the PCT application of control theory to behavior.

 RM: And, of course, this kept him from noticing what Powers saw about these controlled variables: that they are what we typically refer to as the behavior of the organism, what the organism is “doingâ€?. This prevented him from applying control theory correctly to behavior; that is, seeing that control theory had to explain why and how these variables are kept under control. If he had seen it this way – the way Powers saw it – then her would have ve realized that these variables are kept in reference states because organisms can perceive these variables and they have internal specifications (reference signal) for the these perceptions and that differences between internal reference and perception drive the energetic outputs that keep protect these variables from disturbance and keep them in their specified (constant or variable) reference states. So Craik was close but, unfortunately, no cigar.Â

BA: That’s quite an assertion to make, coming from one who has not read Craik’s book. That being the case, you do not know what Craik noticed or understood or realized about controlled variables and their functioning in organisms, and therefore have no legitimate basis on which to make this claim.Â

RM: I have read some of Craik’s papers and they show no evidence of his understanding that what we name as different behaviors – complex things that involve control of complex perceptions, like “balancing a checkbook” – are the constant or variable reference states of controlled variables.Â

BA: But really, what difference would it make if Craik had seen what Powers saw about these controlled variables? Craik’s untimely death in 1945 at age 31 prevented him from continuing this line of theory and research, leaving the field open for Powers’ later development of PCT.

RM: I’m not criticizing Craik; he was surely a very bright and insightful person. I have no problem with people who didn’t understand PCT before Powers developed it. My problem is with people who don’t (or, more accurately, aren’t willing to) understand PCT after Powers developed it.Â

BestÂ

Rick

Richard S. MarkenÂ

"Perfection is achieved not when you have nothing more to add, but when you
have nothing left to take away.�
                --Antoine de Saint-Exupery