Needham once coined a phrase about 'the striving of the blastula to grow into a chicken'. One might call the strategies by which it succeeds the organism's 'pre-natal skills'. After all, the development of the embryo and the subsequent maturation of the newborn into an adult are continuous processes; and we must expect that pre-natal and post-natal skills have certain basic principles in common with each other and with other types of hierarchic processes.
The foregoing section was not intended to describe embryonic development, only one aspect of it: the combination of fixed rules and variable strategies, which we also found in instinctive skills (such as nest-building, etc.) and learnt behaviour (such as language, etc.). 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 associated with symbolic thought.
10
Ontogeny and phylogeny, the development of the individual and the evolution of species, are the two grand hierarchies of becoming. Phylogeny will be discussed in Part Three, but an anticipatory remark is required in our present context of 'rules and strategies'.
Motor-car manufacturers take it for granted that it would make no sense to design a new model from scratch; they make use of already existing sub-assemblies -- engines, batteries, steering systems, etc. -- each of which has been developed from long previous experience, and then proceed by small modifications of some of these. Evolution follows a similar strategy. Compare the front wheels of the latest model with those of an old vintage car or horse-cart -- they are based on the same principles. Compare the anatomy of the fore-limbs of reptiles, birds, whales and man -- they show the same structural design of bones, muscles, nerves and blood-vessels and are accordingly called 'homologous' organs.
The functions of legs, wings, flippers and arms are so different that one would expect them to have quite different designs. Yet they are merely modifications, strategic adaptations of an already existing structure -- the forelimb of the common reptilian ancestor. Once Nature has taken out a patent on a vital component or process, she sticks to it with amazing tenacity: the organ or device has become a stable evolutionary holon. It is as if she felt compelled to provide unity in variety. Geoffroy de St Hilaire, one of the pioneers of modern biology, wrote in 1818: 'Vertebrates are built upon one uniform plan -- e.g., the forelimb may be modified for running, climbing, swimming, or flying, yet the arrangement of the bones remains the same.' [18] That basic arrangement is part of the invariant evolutionary canon. Its utilization for swimming or flying is a matter of evolutionary strategy.
This principle holds all along the line, through all the levels of the evolutionary hierarchy down to the organelles inside the cell, and the DNA chains in the chromosomes. The same standard models of organelles function in the cells of mice and men; the same ratchet-device using a contractile protein serves the motion of amoeba and of the concert-pianist's fingers; the same four chemical molecules constitute the basic alphabet in which heredity is encoded throughout the animal and plant kingdoms -- only the words and phrases formed by them are different for each creature.
If evolution could only create novelties by starting each time afresh from the 'primeval soup', the four thousand million years of the earth's history would not have been long enough to produce even an amoeba. In a much quoted paper on hierarchic structures, H. G. Simon concluded: '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 around to explain the observed predominance of hierarchies among the complex systems Nature presents to us. Among possible complex forms, hierarchies are the ones that have the time to evolve.' [19]
We do not know what forms of life exist on other planets, but we can safely assume that wherever there is life, it is hierarchically organized.
11
Neglect of the hierarchic concept, and the failure to make a categorical distinction between rules and strategies of behaviour, has caused much confusion in academic psychology.* Since its primary concern for the last fifty years was the study of rats in confined spaces ('Skinner boxes'), this failure is hardly surprising. Yet to any spectator of a game of football or chess it is at once obvious that each player obeys rules which determine what he can do, and uses his strategic skills to decide what he will do. In other words, the code defines the rules of the game, strategy decides the course of the game. The examples cited in the previous section indicate that this categorical distinction between rules and strategies is universally applicable to innate and acquired skills, to the hierarchies which make for social coherence, as well as to the hierarchies of becoming.
* It is interesting to note the intense reluctance of academic
psychologists -- even those who have outgrown the cruder forms of
behaviourist S-R theory -- to come to grips with reality. Thus
Professor G. Miller writes in an article on psycholinguistics:
'As psychologists have learnt to appreciate the complexities of
language, the prospect of reducing it to the laws of behaviour so
carefully studied in lower animals [he means Skinner's rats] has
grown increasingly remote. We have been forced more and more into a
position that non-psychologists probably take for granted, namely,
that language is rule-governed behaviour characterized by enormous
flexibility and freedom of choice. Obvious as this conclusion may
seem, it has important implications for any scientific theory of
language. If rules involve the concepts of right and wrong, they
introduce a normative aspect that has always been avoided in the
natural sciences. . . . To admit that language follows rules seems
to put it outside the range of phenomena accessible to scientific
investigation.' [20] What a very odd notion of the purpose and
methods of 'scientific investigation'!
The nature of the code which regulates behaviour varies of course according to the nature and level of the hierarchy concerned. Some codes are innate -- such as the genetic code, or the codes which govern the instinctive activities of animals; others are acquired by learning -- like the kinetic code in the circuitry of my nervous system which enables me to ride a bicycle without falling off, or the cognitive code which defines the rules of playing chess.
Let us now turn from codes to strategies. To repeat it once more: the code defines the permitted moves, strategy decides the choice of the actual move. The next question is: how are these choices made? We might say that the chess-player's choice is 'free' -- in the sense that it is not determined by the rule-book. In fact the number of choices confronting a player in the course of a game of forty moves (while calculating the potential variations which each move might entail two moves ahead) is astronomical. But though his choice is 'free' in the above sense of not being determined by the rules, it is certainly not random. The player tries to select a 'good' move, which will bring him nearer to a win, and to avoid a bad move. But the rule-book knows nothing about 'good' or 'bad' moves. It is, so to speak, ethically neutral. What guides the player's choice of a hoped-for 'good' move are strategic precepts of a much higher complexity -- on a higher level of the cognitive hierarchy -- than the simple rules of the game. The rules a child can learn in half an hour; whereas the strategy is distilled from past experience, the study of master games and specialized books on chess theory. Generally we find on successively higher levels of the hierarchy increasingly complex, more flexible and less predictable patterns of activity with more degrees of freedom (a larger variety of strategic choices); while conversely every complex activity, such as writing a letter, branche
s into sub-skills which on successively lower levels of the hierarchy become increasingly mechanical, stereotyped and predictable.* The original choice of subjects to be discussed in the letter is vast; the next step, phrasing, still offers a great number of strategic alternatives but is more restricted by the rules of grammar; the rules of spelling are fixed with no elbow-room for flexible strategies, and the muscle-contractions which depress the keys of the typewriter are fully automatized.
* Cf. the ethologist's 'fixed action patterns'.
If we descend even further down into the basement of the hierarchy, we come to visceral processes which are self-regulating, controlled by homeostatic feedback devices. These, of course, leave little scope for strategic choices; nevertheless, my conscious self can interfere to some extent with the normally unconscious, automated functioning of my respiratory system by holding my breath or applying some Yoga technique. Thus the distinction between rules and strategies remains in principle valid even on this basic physiological level. But the relevance of this distinction will only become fully apparent in later chapters when we apply it to such fundamental problems as the theory of evolution; free will versus determinism; and the pathology and creativity of the human mind.
12
As already mentioned, the purpose of this chapter is not to provide a manual of hierarchies, but to convey some idea of the conceptual framework on which this inquiry is based, and to give the reader the 'feel' of hierarchic thinking as opposed to the current reductionist and mechanistic trends. To conclude this summary survey, I must mention, however briefly, a few more principles which all hierarchic systems have in common.
One obvious point is that hierarchies do not operate in a vacuum, but interact with others. This elementary fact has given rise to much confusion. If you look at a well-kept hedge surrounding a garden like a living wall, the rich foliage of the entwined branches may make you forget that the branches originate in separate bushes. The bushes are vertical, arborizing structures. The entwined branches form horizontal networks at numerous levels. Without the individual plants there would be no entwining, and no network. Without the network, each plant would be isolated, and there would be no hedge and no integration of functions. 'Arborization' and 'reticulation' (net-formation) are complementary principles in the architecture of organisms and societies. The circulatory system controlled by the heart and the respiratory system controlled by the lungs function as quasi-autonomous, self-regulating hierarchies, but they interact on various levels. In the subject-catalogues in our libraries the branches are entwined through cross-references. In cognitive hierarchies -- universes of discourse -- arborization is reflected in the 'vertical' denotation (classification) of concepts, reticulation in their 'horizontal' connotations in associative nets.
The complementarity of arborization and reticulation yields relevant clues to the complex problem of how memory works.*
* The section that follows is a summary of The Act of Creation,
Book II, Ch. X, The Ghost in the Machine, Ch. V and VI,
and of a paper read to the Harvard Medical School Symposium on
'The Pathology of Memory'. [21]
13
In Stevenson's novel Kidnapped, Alan Breck makes the casual remark: 'I have a grand memory for forgetting, David.' He speaks for all of us, and not only those afflicted with aphasia or senility. Painful as it is, we have to admit that a large proportion of our memories resembles the dregs in a wine glass, the dehydrated sediments of experiences whose flavour has gone -- or, to change the metaphor, they are like dusty abstracts of past events on the shelves of a dimly lit archive. Fortunately this applies only to one type or category of memories, which I shall call abstractive memory. But there is another category, derived from our capacity to recall past episodes, or scenes, or details of scenes, with almost hallucinatory vividness. I shall call this the spotlight type of memory, and I shall contend that 'abstractive memory' and 'spotlight memory' are different classes of phenomena, based on different neural mechanisms.
Take abstractive memory first. The bulk of what we can remember of our life history, and of the knowledge we have accumulated in the course of it, is of the abstractive type.
The word 'abstract' has, in common usage, two main connotations: it is the opposite of 'concrete', in the sense that it refers to a general concept rather than a particular instance; in the second place, an 'abstract' is a condensation of the essence of a longer document. Memory is abstractive in both senses. I watch a television play. The exact words of each actor are forgotten within a few seconds; only their abstracted meaning is retained. The next morning I can only remember the sequence of scenes which constituted the story. A month later, all I can remember is that the play was about a gangster on the run. Much the same happens to the mnemic residues of books one has read and whole chapters of one's own life-story. The original experience has been stripped of detail, skeletonized, reduced to a colourless abstract before being confined to the memory store. The nature of that store is still a complete mystery in brain-research, but it is obvious that if stored knowledge and experience are to be retrievable (for otherwise they would be useless), they must be ordered according to the hierarchic principle -- like a thesaurus or a library subject-catalogue, with headings and sub-headings but also with a wealth of cross-references to assist the process of retrieval (the former representing arborization, the latter the reticulation of the hierarchic structure). If we pursue for a moment the metaphor of a library representing our memory stores, we arrive at rather depressing conclusions. Quite apart from the countless volumes that are left to rot away or fall to dust, there is a hierarchy of librarians at work who ruthlessly condense long texts into short abstracts and then make abstracts of the abstracts.
This process of sifting and abstracting actually starts long before a lived experience is confined to the memory store. At every relay station in the perceptual hierarchy through which the sensory input must pass before being admitted to consciousness it is analysed, classified and stripped of irrelevant detail.* This enables us to recognize the letter R in an almost illegible scrawl as 'the same thing' as a huge printed R in a newspaper headline, by a sophisticated scanning process which disregards all details and abstracts only the basic geometrical design -- the 'R-ness' of the R -- as worth signalling to higher quarters. This signal can now be transmitted in a simple code, like a message in Morse, which contains all the relevant information -- 'it's an R' -- in a condensed, skeletonized form; but the wealth of calligraphic detail is of course irretrievably lost, as the inflections of the human voice are lost in the Morse message. The wistful remark 'I have a memory like a sieve may be derived from an intuitive grasp of these filtering devices which operate all along the input channels and storage channels of the nervous system.
* The psychologist distinguishes on the lower levels of the hierarchy
lateral inhibition, habituation, and efferent control of the
receptors; on the higher levels the mechanisms responsible for
the visual and auditory constancy phenomena, and the scanning and
filtering devices that account for pattern recognition and enable
us to abstract universals.
Yet even the chosen few among the multitude of potential stimuli incessantly bombarding our receptor organs which have successfully passed all these selective filters and have attained the status of consciously perceived events, must submit, as we have seen, to further rigorous stripping procedures before being admitted to the permanent memory store; and as time passes, they will suffer further decay. Memory is a prize example of the law of diminishing returns.
This retrospective impoverishment of lived experience is unavoidable; 'abstractive memory implies the sacrifice of particulars. If, instead of abstracting generalized concepts, like 'R' or 'tree' or 'dog', our memories consisted of a collection of all our particular experiences of R's and trees and dogs encountered in the past -- a storehouse of lantern slides and tape -- recordings -- it wou
ld be a chaotic jumble, completely useless for mental guidance, for we would never be able to identify an R or understand a spoken sentence. Without hierarchic order and classification, memory would be bedlam (or the parroting of sequences learned by rote, and reinforced by conditioning, which is the behaviourist's model -- or caricature -- for remembering).
To say it again: the loss of particulars in abstractive memory is unavoidable. Fortunately this is not the whole story, for there are several compensating factors which, at least in part, make up for the loss.
In the first place, the abstractive process can acquire a higher degree of sophistication by learning from experience. To the novice, all red wines taste alike, and all Japanese males look the same. But he can be taught to superimpose more delicate perceptual filters on the coarser ones, as Constable trained himself to discriminate between diverse types of clouds and to classify them into sub-categories. Thus we learn to abstract finer and finer nuances -- to make the trees of the hierarchies of perception grow new shoots, as it were.
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