APPENDICES
APPENDIX I
BEYOND ATOMISM AND HOLISM -- THE CONCEPT OF THE HOLON *
* This edited version of a paper read at the Beyond Reductionism Symposium at Alpbach, 1968 [3], is intended as a summary of Part One, 'Outline of a System' (Chapters I-V). Unavoidably some passages are repetitive, others rather technical. The general reader can safely skip Appendices I - III.
This is going to be an exercise in General Systems Theory -- which seems to be all the more appropriate as Ludwig von Bertalanffy, its founding father, sits next to me. It seems equally appropriate that I should take as my text a sentence from Ludwig's Problems of Life [1]; it reads: 'Hierarchical organization on the one hand, and the characteristics of open systems on the other, are fundamental principles of living nature.'
If we combine these two fundamental principles, and add a dash of cybernetics to them, we get a system-theoretical model of Self-regulating Open Hierarchic Order, or SOHO for short. I intend to discuss some of the properties of this SOHO model as an alternative to the S-R model of linear causation, derived from classical mechanics, which we seem to be unanimous in rejecting. I can only give here a sketchy outline of the idea, but I have tried to tabulate the axioms and propositions relating to it in a more systematic way in an appendix to my last book, [2] which I have also appended to this paper, as a sort of Tractatus Logico Hierarchicus. Some of these propositions may appear trivial, others rest on incomplete evidence, still others will need correcting or qualifying. But they may provide a basis for discussion.
HIERARCHIES AND OLD HATS
When one talks about hierarchic organization as a fundamental principle of life, one often encounters a strong emotional resistance. For one thing, hierarchy is an ugly word, loaded with ecclesiastic and military associations, and conveys to some people a wrong impression of a rigid or authoritarian structure. (Perhaps the assonance with 'hieratic', which is a quite different matter, plays a part in this confusion.) Apart from this, the term is often wrongly used to refer simply to order of rank on a linear scale or ladder (e.g. Clark Hull's 'habit-family hierarchies'). But that is not at all what the term is meant to signify. Its correct symbol is not a rigid ladder but a living tree -- a multi-levelled, stratified, out-branching pattern of organization, a system branching into sub-systems, which branch into sub-systems of a lower order, and so on; a structure encapsulating sub-structures and so on; a process activating sub-processes and so on. As Paul Weiss said yesterday: 'The phenomenon of hierarchic structure is a real one, presented to us by the biological object, and not the fiction of a speculative mind.' It is at the same time a conceptual tool, a way of thinking, an alternative to the linear chaining of events torn from their multidimensionally stratified contexts.
All complex structures and processes of a relatively stable character display hierarchic organization, and this applies regardless whether we are considering inanimate systems, living organisms, social organizations, or patterns of behaviour. The linguist who thinks primarily in terms of Chomsky's [4] hierarchic model experiences a déjà vu reaction -- as McNeill expressed it -- towards the physiologist's intracellular hierarchy; and this may equally apply to Bruner's presentation of the hierarchic structure of voluntary action. In this essential respect -- and in others that I shall mention -- these processes in widely different fields are indeed isomorphic. The hierarchic tree diagram may serve equally well to represent the branching out of the evolution of species -- the tree of life and its projection in taxonomy; it serves to represent the step-wise differentiation of tissues in embryonic development; it may serve as a structural diagram of the parts-within-parts architecture of organisms or galaxies, or as a functional schema for the analysis of instinctive behaviour by the ethologist; [5] or of the phrase-generating machinery by the psycholinguist. It may represent the locomotor hierarchy of limbs, joints, individual muscles, and so down to fibres, fibrils and filaments; [6] or, in reverse direction, the filtering and processing of the sensory input in its ascent from periphery to centre. It could also be regarded as a model for the subject-index of the Library of Congress, and for the organization of knowledge in our memory-stores; as an organizational chart for government administrations, military and business organizations; and so on.
This almost universal applicability of the hierarchic model may arouse the suspicion that it is logically empty; and this may be a further factor in the resistance against it. It usually takes the form of what one may call the 'so what' reaction: 'all this is old hat, it is self-evident' -- followed by the non sequitur 'and anyway, where is your evidence?' Well, hierarchy may be old hat, but I would suggest that if you handle it with some affection, it can produce quite a few lively rabbits.
EVOLUTION AND HIERARCHIC ORDER
One of my favourite examples to illustrate the merits of hierarchic order is an amusing parable invented by Herbert Simon -- whose absence we all regret. I have quoted it on other occasions, but I shall briefly quote it again. The parable concerns two watchmakers, Hora and Tempus. Both make watches consisting of a thousand parts each. Hora assembles his watches bit by bit; so when he pauses or drops a watch before it is finished, it falls to pieces and he has to start from scratch. Tempus, on the other hand, puts together sub-assemblies of ten parts each; ten of these sub-assemblies he makes into a larger sub-assembly of a hundred units; and ten of these make the whole watch. If there is a disturbance, Tempus has to repeat at worst nine assembling operations, and at best none at all. If you have a ratio of one disturbance in a hundred operations, then Hora will take four thousand times longer to assemble a watch -- instead of one day, he will take eleven years. And if, for mechanical bits, we substitute amino-acids, protein molecules, organelles, and so on, the ratio between the time-scales becomes astronomical.
This is one basic advantage of employing the hierarchic method. The second is, of course, the incomparably greater stability and resilience to shock of the Tempus type of watch, and its amenability to repair and improvement. Simon concludes:
Complex systems will evolve from simple systems much more rapidly if there are stable intermediate forms than if there are not. The resulting complex forms in the former case will be hierarchic. We have only to turn the argument round to explain the observed predominance of hierarchies among the complex systems Nature presents to us. Among possible complex forms, hierarchies are the ones that had the time to evolve. [7]
If there is life on other planets, we may safely assume that, whatever its form, it must be hierarchically organized.
Motor manufacturers discovered long ago that it does not pay to design a new model from scratch by starting on the level of elementary components; they make use of already existing sub-assemblies -- engines, brakes, etc. -- each of which has developed from long previous experience, and then proceed by relatively small modifications of some of these. Evolution follows the same strategy. Once it has taken out a patent it sticks to it tenaciously -- Thorpe remarked yesterday on its fixed conservative ways. The patented structure, organ or device acquires a kind of autonomous existence as a sub-assembly. The same make of organelles functions in the cells of mice and men; the same make of contractile protein serves the streaming motion of amoeba and the finger muscles of the piano-player; the same homologous design is maintained in the vertebrate forelimb of man, dog, bird and whale. Geoffroy de St Hilaire's loi du balancement, and d'Arcy Thompson's [8] transformation of a baboon's skull into a human skull by harmonious deformations of a Cartesian coordinate lattice, further illustrate the hierarchic constraints imposed on evolutionary design.
AUTONOMOUS HOLONS
The evolutionary stability of these sub-assemblies -- organelles, organs, organ-systems -- is reflected by their remarkable degree of autonomy or self-government. Each of them -- a piece of tissue or a whole heart -- is capable of functioning in vitro as a quasi-independent whole, even though isolated from the organism or transplanted into another organism. Each is a sub-whole which, towards its subordinated parts
, behaves as a self-contained whole, and towards its superior controls as a dependent part. This relativity of the terms 'part' and 'whole' when applied to any of its sub-assemblies is a further general characteristic of hierarchies.
It is again the very obviousness of this feature which tends to make us overlook its implications. A part, as we generally use the word, means something fragmentary and incomplete, which by itself would have no legitimate existence. On the other hand, there is a tendency among holists to use the word 'whole' or 'Gestalt' as something complete in itself which needs no further explanation. But wholes and parts in this absolute sense do not exist anywhere, either in the domain of living organisms or of social organizations. What we find are intermediary structures on a series of levels in ascending order of complexity, each of which has two faces looking in opposite directions: the face turned toward the lower levels is that of an autonomous whole, the one turned upward that of a dependent part. I have elsewhere [9] proposed the word 'holon' for these Janus-faced sub-assemblies.
The concept of the holon is meant to supply the missing link between atomism and holism, and to supplant the dualistic way of thinking in terms of 'parts' and 'wholes', which is so deeply engrained in our mental habits, by a multi-level, stratified approach. A hierarchically-organized whole cannot be 'reduced' to its elementary parts; but it can be 'dissected' into its constituent branches of holons, represented by the nodes of the tree-diagram, while the lines connecting the holons stand for channels of communication, control or transportation, as the case may be.
FIXED RULES AND FLEXIBLE STRATEGIES
The term holon may be applied to any stable sub-whole in an organismic, cognitive, or social hierarchy which displays rule-governed behaviour and/or structural Gestalt constancy. Thus biological holons are self-regulating open systems' [10] governed by a set of fixed rules which account for the holon's coherence, stability and its specific pattern of structure and function. This set of rules we may call the canon of the holon.* The canon determines the fixed, invariant aspect of the open system in its steady state (Fliessgleichgewicht -- dynamic equilibrium); it defines its pattern and structure. In other types of hierarchies, the canon represents the codes of conduct of social holons (family, tribe, nation, etc.); it incorporates the 'rules of the game' of instinctive rituals or acquired skills (behavioural holons); the rules of enunciation, grammar and syntax in the language hierarchy; Piaget's 'schemes' in cognitive hierarchies, and so on. The canon represents the constraints imposed on any rule-governed process or behaviour. But these constraints do not exhaust the system's degrees of freedom; they leave room for more or less flexible strategies, guided by the contingencies in the holon's local environment.
* Cf. the 'organizing relations' or 'laws of organization' of earlier writers on hierarchic organization (e.g., Woodger (1929), Needham (1941), and the 'system-conditions' in general system theory.
It is essential at this point to make a sharp, categorical distinction between the fixed, invariant canon of the system and its flexible (plastic, variable) strategies. A few examples will illustrate the validity of this distinction. In ontogeny, the apex of the hierarchy is the zygote, and the holons at successive levels represent successive stages in the development of tissues. Each step in differentiation and specialization imposes further constraints on the genetic potential of the tissue, but at each step it retains sufficient developmental flexibility to follow this or that evolutionary pathway, within the range of its competence. guided by the contingencies of the cell's environment -- Waddington's [11] 'strategy of the genes'. Turning from embryonic development to the instinctive activities of the mature animal, we find that spiders spin webs, birds build nests according to invariant species-specific canons, but again using flexible strategies, guided by the lie of the land: the spider may suspend its web from three, four or more points of attachment, but the result will always be a regular polygon. In acquired skills like chess, the rules of the game define the permissible moves, but the strategic choice of the actual move depends on the environment -- the distribution of the chessmen on the board. In symbolic operations, the holons are rule-governed cognitive structures variously called 'frames of reference', 'universes of discourse', 'algorithms', etc., each with its specific 'grammar or canon; and the strategies increase in complexity on higher levels of each hierarchy. It seems that life in all its manifestations, from morphogenesis to symbolic thought, is governed by rules of the game which lend it order and stability but also allow for flexibility; and that these rules, whether innate or acquired, are represented in coded form on various levels of the hierarchy, from the genetic code to the structures in the nervous system responsible for symbolic thought.
TRIGGERS AND SCANNERS
Let me discuss briefly some specific characteristics of what one might loosely call output hierarchies, regardless whether the 'output' is a baby, or a sentence spoken in English. However much their products differ, all output hierarchies seem to have a classic mode of operation, based on the trigger-releaser principle, where an implicit coded signal which may be relatively simple, releases complex, pre-set mechanisms.
Let me again run through a few examples. In phylogeny, Waddington [12] and others have convincingly shown that a single favourable gene-mutation can act as a trigger to release a kind of chain-reaction which affects a whole organ in a harmonious way. In ontogeny, the prick of a fine platinum needle on the unfertilized egg of a frog or sheep triggers off parthenogenesis. The genes act as chemical triggers, catalysing reactions. The implicit four-letter alphabet of the DNA chain is spelled out into the explicit, twenty-letter alphabet of amino-acids; the inducers or evocators, including Spemann's 'general organizer', again turn out to be relatively simple chemicals which need not even be species-specific to activate the genetic potentials of the tissue. In instinct behaviour, we have releasers of a very simple kind -- the red belly of the stickleback, the spot under the herring-gull's beak, which trigger off the appropriate behaviour. [13] In the performance of acquired skills you have the same process of step-wise filling in the details of implicit commands issued from the apex of the hierarchy, such as 'strike a match and light this cigarette' or 'sign your name', or 'use your phrase-generating machine' to transform an unverbalized image into innervations of the vocal chords.
The point to emphasize is that this spelling-out process, from intent to execution, cannot be described in terms of a linear chain of S-R units, only as a series of discrete steps from one open sesame, activated by a combination lock, to the next. The activated holon, whether it is a government department or a living kidney, has its own canon which determines the pattern of its activity. Thus the signal from higher quarters does not have to specify what the holon is expected to do; the signal merely has to trigger the holon into action by a coded message. Once thrown into action, the holon will spell out the implicit command in explicit form by activating its sub-units in the appropriate strategic order, guided by feedbacks and feed-forwards from its environment. Generally speaking, the holon is a system of relations which is represented on the next higher level as a unit, that is, a relatum.