Closed and open systems

Excerpt from chapter 8 of [W. Koehler](, _The Place of Values in the World of Fact_, Liveright, 1938, pp. 314-28. [[on Google Books](] [[via WorldCat](] Snippets of text (from the beginning, maybe the middle, and the end) appear below, to give a sense of the content for the chapter. For more depth, the original source is cited, above. ---

As it became more and more apparent that the machine principle is not capable of giving us a satisfactory explanation of organic regulation, an interpretation in more functional or dynamic terms began to attract some theorists. * At first it seems indeed a plausible assumption that in the organism fitting regula-tion toward a standard status occurs for the same reasons that make physical systems attain or re-establish an equilibrium. * Unfortunately, however, the concept of 'equilibrium' is in this connexion often used in just as vague a meaning as had previously been the case with the concept 'machine'. It appeared therefore advisable to analyse physical regulation before a comparison was undertaken between the normal state of an organism and an equilibrium in physics. [p. 59, editoral paragraphing added]

On the face of it, these standard states seem to resemble each other in a most promising manner. There is besides a special point wlvch gives an equilibrium theory of organic regulation a particularly inviting appearance. * Physical systems, we have found, tend to transform themselves in the direction of an equilibrium for two reasons: either because their processes follow the second law of thermodynamics, or because the law of dynamic direction applies to them. * Now, even the most superficial consideration of the organism must convince everybody that its normal state cannot be a mere thermodynamic equilibrium. If therefore, an equilibrium theory of organic regulation is to be at all proposed, this can be done only with the premise that * both the law of dynamic direction and * the second law apply to the organism; * in other words, that the organism regulates toward a balance of directed vectors no less than it does toward 'a most probable situation'. We have seen, however, that the law of dynamic direction does not determine what actually happens in a system, unless there is sufficient friction by which inert macroscopic velocities are eliminated. * Is this condition fulfilled in an organism? * Without any doubt it is. * In the movements of our limbs and in circulation inert velocities may perhaps play a modest role. * In the tissue, however, friction is as great as it is in the interior of any solution. Consequently there are no such velocities in the tissue. What happens here must, from the point of view of physics, follow either from the second law or from the law of dynamic direction. * In the former case we could say with the physicists that changes will occur in the direction of 'higher probabilities'; * in the second case, that displacements will be proportional to, and in the direction of, the vectors which happen to obtain at each point. [p. 59-60, editoral paragraphing added]


In the introductory chapter of his book Cannon (1932) remarks that 'the constant conditions which are maintained in the body might be termed _equilibria_'. * The author does not say what relation he assumes to obtain between this functional principle and his own view according to which regulation seems always to be due to regulating devices. * At any rate, he prefers to give the name _homeostasis_ to the fact that certain 'steady states' are so obstinately preserved or re-established in the organism. * Equilibria, he adds, are found in simple closed systems, 'where known forces are balanced'. * Again, he says, the word homeostasis 'does not imply something set and immobile, a stagnation'. There is something in these last words which many biologists may appreciate when attempts are made to explain organic regulation by an 'equilibrium theory'. [p. 62, editoral paragraphing added] [....]

In Professor A. V. Hill's words (1931, p. 60): * _'If there be no equilibrium, how far dare we apply rules and formulae derived from the idea of equilibrium?'_ In several statements the same author hints at a possible answer. All physiologists, he says, * 'must have exercised their minds as to the reason why a living cell, completely at rest, and doing nothing at all except maintain its continued existence, requires a continual supply of energy' (Hill, 1931, p. 4). [p. 63, editoral paragraphing added] [....]

Life has sometimes been compared to a flame (e.g. Roux, 1914, p. 17, p. 79). This is more than a poetical metaphor, since, from the point of view of function and energetics, life and a flame have actually much in common. [p. 63] [....]

We are now in a position to apply our theoretical concepts to the flame and then to the organism. * The flame is not a closed system. * It can, however, be considered as part of a larger system for which our general principles are valid. * If this be done certain consequences will follow for the behaviour of the flame as such. The air of the environment and the substance of the candle, taken together, contain amounts of chemical energy which are to all practical purposes unlimited. * If therefore the material of the candle and a sufficiently large volume of air are included, we obtain a 'system' which we may regard as closed; because during the lifetime of the flame the energy on which its steady state depends will be exclusively supplied by the candle and this volume of air. [p. 64, editoral paragraphing added] [....]

A general view of the organism shows us a situation which resembles strongly that of the flame. * The organism is not a closed system; it is part of a larger functional context, the external section of which contains as its most important components oxygen and food, i.e. a store of chemical energy which may be regarded as practically unlimited. In one respect there is a difference between the flame and the organism : * unlike the flame, the organism itself normally contains great reserves of food in the widest sense of the word; it is stored, for instance, in the liver. From these sources rather than from the outside other tissues receive their food supply directly. [p. 65-66, editoral paragraphing added] [....]

There is no apparent reason, however, why science should hesitate to deal with the problem of _regulation_. Nor is there any essential difficulty in the fact that organic regulation is generally directed toward an 'optimum' state. The physicists, it is true, have not given much attention to this functional possibility, although it follows from their general laws. Also, a thorough investigation of _heterogeneous_ physical systems and of their regulatory behavior would contribute greatly to a further understanding of organic fitness. But even now we can predict from known principles that some such systems will show an impressive causal harmony by which they themselves keep in a 'healthy' condition, as though this were their goal. [p. 68]

It is perhaps too early for final statements in this field, particularly since we know so little about the way in which evolution has created the living world. As this world now is, however, the following seems to me a conservative description of the situation: no procedure of science reveals any actual participation of demands and values in the determination of organic events. At the same time, science can clearly demonstrate that in certain systems function will, for dynamic reasons, take a most 'fitting' course. We do not discover requiredness as such among the data of science. But a general trend of nature is sometimes found to yield the same results as might be expected if the events in question were actually happening in order to fulfil a demand. [p. 69]