INTERNATIONAL CYBERNETICS NEWSLETTER
THE ICNL “FOUNDING FATHERS” SERIES II
THE CYBERNETICS OF GORDON PASK – Part 1
Bernard Scott, Ph.D.
Scott, B. (1980). "The Cybernetics of Gordon Pask, part 1", Int. Cyb. Newsletter, 17, pp 327-
336.
Introduction
Regular readers will remember the carefully researched, perceptive survey of Heinz von
Foerster by Dr Bernard Scott in ICNL 12, pp 209-214.
We are very pleased to publish today Part I of a similar analytical overview of professor Dr
Gordon Pask’s output by the same author, who, as a senior member of System Research Ltd, has worked closely with Gordon Pask and his team. (Paul Hanika, Editor, ICNL)
Overview
For convenience of exposition (and publication) this review of the work of Gordon Pask is in two parts, ordered chronologically. The first part concludes with reference to a seminal paper
(Park 1969a) in which Pask argued the need for a cybernetics which could successfully address itself, in a full-blooded sense, to the problem of human cognition and consciousness.
The requirements to be met by such a theory were spelled out; their statement represented the distillation of Park’s work as a cybernetician which, at that stage, already spanned nearly two decades.
Pask responded to his own challenge and in the following years (in association with
Kallikourdis and Scott) produced what he, himself, recognises as his major work: conversation theory and its several applications in education and decision making (v ICNL 7 for a recent statement of progress by the research team).
Conversation theory and its chief areas of application are addressed in Part 2 of this article.
Part 1 – Genesis of Theory
In Pask (1966), the author reports an “emotional impact” on first reading Weiner’s (1948) classic Cybernetics . To the young Cambridge medical student (his degree, when it came, was in physiology), with a diverse background and interests in chemistry, geology and psychology, the book brought fully to consciousness a sense of unity in nature and man’s endeavours that, thus far, had been latent in his own eclecticism. Here was the vision and the final justification for the generalist: the twentieth century version of Renaissance man was born.

In those early years in Cambridge, Pask developed his interests in the work of the information theorists (Hick, Crossman, Broadbent) who, following the pioneering spirit of Bartlett were to lay the foundations for the contemporary dominance of the “information-processing” approach in experimental psychology.
At the same time, he began work on the design and development of “learning machines”: the hardware forebears of today’s artificial intelligences (v Pask 1965).
Somehow he found time to continue his interest in the theatre, cross-fertilising his interests with the creation of an adaptive “musi-colour” system that not only anticipated the light shows of popular music concerts by several years but is still, in conception, of greater sophistication.
As well as machines that would adapt to a performer or audience and entertain, Pask developed systems that would adapt to a learner and teach.
As early as 1958, he had produced a commercially available system, SAKI, an “adaptive teaching machine” for the instruction of keyboard skills (v Pask 1958). His interest in the fruitful juxtaposition and symbiosis of man and machine, particularly in the area of education, has continued to this day. It’s fair to say that, only now, more than twenty years on, has the evolution of computing power become such that his vision of the automated classroom (v Pask 1961 chapter 6) become an imminent reality.
During these years, Pask styled himself as a “mechanic philosopher”; he has always been at pains to emphasise the role of theoretical insight and speculation in the development and design of new technologies. Indeed, from the perspective adopted in this article, Pask’s primary role has not been that of a system builder or gadgeteer but that of thinker and theoretician, who has been impelled, on critically thought out methodological grounds, at each stage in the development of radical theory, to embody the theory in an artefact.
I think here lies a major confusion for many who come to Pask’s work: their tastes may give them an interest in his systems and in the associated empirical findings when they are employed in education or experimental psychology; alternatively (and, perhaps, more rarely) their tastes may give them an interest in his work as a theoretician and philosopher of cybernetics. With the former approach, Pask’s published work appears esoteric, pedantic, obscurantist. With the latter approach, the need to come to terms with the working details of new technologies (hardware, software) may lead to a failure to grasp the full power and meaning of Pask’s abstractions.
Since those early years, Pask has bee prolific as a research worker, writer and international envoy for cybernetics. He has had published more than a hundred and fifty papers, including four book length monographs, as well as handling the report and proposal writing chores of an independent research team (System Research Ltd), holding part-time chairs at Brunel
University and the Open University and serving as visiting professor in the Universities of
Illinois (at Urban and Chicago Circle) and Atlanta, Georgia.
His course and commitment to cybernetics was set in 1959 on the occasion of the (by now, legendary) conference on “The Mechanisation of Thought Processes” at the National
Physical Laboratory in London. That conference brought together workers and thinkers in cybernetics and associated disciplines from all over the world, being both a summation of

work to date and the establishment of a platform from which future work was to develop
(notable participants were Stafford Beer, Heinz Von Foerster, Warren McCulloch, Donald
Mackay, Marvin Minsky, Ross Ashby and Oliver Selfridge).
Pask’s own paper (Pask 1959) established his reputation as a controversial and original thinker. Entitled “Physical Analogies to the Growth of a Concept”, it contained theoretical discussion of the nature of learning and evolution accompanied by the demonstration of purely physical phenomena (growth of crystals at electrodes suspended in an electrolytic solution) that could serve as an adaptive medium for computing equivalences (conditioning) and as dynamic, regenerative storage medium (memory). Unlike many others of Pask’s visions and insights, this one, of the “chemical” or “organic” computer, has yet to be. One awaits the next generation of computers (after the silicon chip) with interest.
At that conference, Pask established a close relationship with the late Warren McCulloch, which continued until the latter’s death. McCulloch was the chief of Pask’s mentors, as Pask has acknowledged on many occasions. Although their explicit areas of interest and approaches to research differed enormously (Pask, chiefly an experimental psychologist,
McCulloch, chiefly a neurophysiologist – v McCulloch 1965) they shared a parallel view of the nature of consciousness and reality and a belief in the power of the abstract concepts of cybernetics to bring some rational order to that view. Telling examples are McCulloch’s own formulation of the concept of heterarchical organisation and the associated “principle of the redundancy of potential command”. He, himself, applied these concepts to the analysis of the workings of the reticular formation in vertebrates. As we shall see, the same concepts have guided Pask’s work on human learning and cognition.
Also at that conference, Pask met Heinz Von Foerster and established a similarly fruitful intellectual association. (I referred to this association in an earlier article in ICNL, Scott
1979).
Pask spent a year with Von Foerster at the University of Illinois, Urbana and the two cooperated on research concerning the establishment of cooperation and conflict in small groups (Park and Von Foerster 1960, 1961).
On his return to England, System Research Ltd was established as a non-profit research organisation and a programme of research was begun (financed chiefly by grants from the US
Army and Air Force) concerning human learning, the development of computer simulations and other models for learning processes, the (continued) study of small group interaction and the development of adaptively controlled systems that, on the one hand, demonstrably facilitated the acquisition of perceptual motor skills and, on the other hand, demonstrably facilitated the efficiency of small group communication, learning, and problem-solving.
In toto, this work spans the decade of the sixties and beyond and has been well summarised by Pask himself (Pask 1975). His chief collaborators in those years were the psychologist, B
N Lewis and, more briefly, a computer scientist, G L Mallen. The author of this article joined the team as research assistant toward the end of this period, in 1967, and, albeit from a lowly position, was able to reconstruct the history to date and to witness and to some extent contribute to the developments that followed.
Given the volume of Pask’s output and the range of his thought, any review has to be selective. In the following sections, I give brief accounts of his work, organised under the

headings “Learning as an evolutionary process”, “Teaching and learning by machine” and
“Social cybernetics”. As I hope will become clear, the hallmark of cybernetic thought is its unitary nature. In the final section, as the bridge to Part 2, I show, as promised, how Pask himself brought the strands together in his address to the first World Congress of Cybernetics
(Pask 1969).
Part 2 – Learning as an Evolutionary Process
As far as I know, Pringle (v Pringle 1951) was one of the first to articulate in some detail the analogy between evolution and speciation and human earning and adaptation. He developed a descriptive model of the brain as a medium for the evolution of more and more complex forms of organisation. His neurophysiological speculations were paralleled by Crossman’s
(1959) psychological theory of skill organisation in which stable behaviours are selected from an initially diverse population. From his posthumous writings (Craik 1966), we know that
Kenneth Craik, too, had a similar vision of the mechanisms underlying learning and adaptation.
It was Ross Ashby (1956) who clarified the concepts most elegantly: from the perspective of abstract cybernetics, evolution of more complex forms is a necessary consequence of applying a constraint (a rule or principle of selection) to a system with a relatively large number of (initially) “uncoupled” parts.
Pask (for whom Ross Ashby was a constant source of inspiration) understood from Ashby’s abstract theory that the medium of evolution and the nature of the evolving entities are irrelevant. This freed him from a concern with the particulars of brain organisation to concentrate on what he later referred to as the "symbolic evolution” of concepts (Pask
1972a). From the early sixties on, he was concerned to explicate and model the complex processes of mentation (v Pask 1968a) as abstract systems constrained by well-defined properties. In Beer’s terms, these are the “fabric” properties found in any brain-like or, in general, organic system:
 There is a limit on the resources available (be they conceptualised as “storage space”,
“free energy”, or “processing time”).

The basic units or parts out of which a self-organising system is constructed or modelled are themselves just such self-organising systems.

The system and its parts are active.
Pask’s telling phrase was that “man is a system who needs to learn”; within the limits of
“boredom” and “fatigue” he is always learning, always engaged in a species of symbolic evolution.
As well as the special purpose computers or “learning machines” mentioned above, Pask (in association with Feldman and Mallen) pioneered the use of computer programs to simulate learning and evolution.
Several models (v Pask 1969b) simulate the evolution of populations of self-reproducing automata on a tessellation competing for the resource of “food” or “energy”. Their intent was to demonstrate the ubiquity of the evolution of more complex forms of automata (as hybrids or cooperatives) even in such a highly abstracted and artificial universe.

A different class of models (developed chiefly in association with G L Mallen) simulate the processes whereby skilled behaviour are acquired by a human operator.
In these models, Park first fully articulated his conception of learning as a hierarchical process. At level 1, problem-solving procedures compete for execution; at level 2, higher order problem-solving procedures monitor, construct and select among the lower level procedures, they themselves competing for execution. Further levels maybe invoked to account for creativity, insight and the development of cognitive structures in ontogenesis
(Pask 1966 models the developmental psychologies of Piaget and Vyzotsky in this way).
In his several accounts of these models (see also Pask 1963, 1966b) Pask is always at pains to point out that the hierarchy of control processes is an abstraction invoked by the observer in order to give a reasoned account of cognition: the reality of cognition is, in McCulloch’s phrase, heterarchical. The distinction between levels of control is a necessary consequence of the initial decision to distinguish processes (as symbolic or program-like entities) from the processors in which they are executed. Without these distinctions, the observer finds that not only has his system no “top” or “bottom”, it also has no boundaries to distinguish it from its environment, which, by the same token, includes the observer himself. This, I think, is perhaps the heart of Pask’s contribution as an epistemologist: his recognition that certain distinctions have to be made if the observer is to break out from his solipsistic silence and that, having made those initial distinctions, certain consequences follow necessarily, having import in a very general sense for the whole methodology of the cybernetician. With these concerns, he clearly anticipated the classic work of Spencer-Brown (1969), The Laws of
Form.
Part 3 – Teaching and Learning by Machine
As noted in the introduction, the main core of Pask’s work on human learning has continually sought application in the real world of education and training.
At the time when teaching machines and programmed learning first became fashionable, following the writings of the behaviourist B F Skinner, Pask articulated the cybernetic view that “teaching is a control process” and, freed form the ideological requirement to fit his work to the paradigms of operant conditioning and schedules of reinforcement, set about, in a thoroughly pragmatic manner, the design and development of machines that did, indeed, teach in the required sense.
At the same time, his systems served as an embodiment (Pask’s phrase) for the theory of learning described (albeit briefly) in the previous section.
The systems in question have a long history which has been well documented by Pask himself (Pask 1972b, 1975). Their development excited international interest and parallel work was carried out by, among others, Stolhurow, Gaines, Briggs, Hudson and Kelley.
As Gaines notes in his survey of the field, “Pask has made available a very deep and comprehensive discussion of automated training and has placed it in the general context of interactions between self-organising systems” (Gaines 1967, p7).
The essential feature of an adaptive teaching machine is that it monitors a learner’s performance so as to pose problems at the level of difficulty most conducive to effective

learning: as the student’s performance improves so the level of difficulty is increased. This may be achieved in several, parallel ways by several feedback loops (for example frequency of stimulus presentation, complexity of stimuli presented). Where the skill has a clearly articulated structure, higher order feedback can monitor and integrate distinct subskills (Pask and Scott 1969 contains a description of one of the most sophisticated systems developed, in this case for the skill of teleprinter operation).
Pask and Lewis (1968) give an account of an experimental system where they argue that such adaptive, responsive environments are what is required to observe a self-organising system, referring to the methodology as a “null-point” or “steady-state” approach.
The admission of a flaw in the methodology led to the first systems in which the full logic of a conversational interaction was embodied, albeit in embryonic form.
The basic assumption of the earlier systems was that the student would abide by the agreement to attempt to perform the skill effectively at all times. Pask and Lewis noted a tendency for some subjects to override the adaptive controller by selectively making deliberate errors. In this way, the subject himself could determine which component of a skill was rehearsed. Clearly, such subjects were imposing their own learning strategy on the system. A series of studies (v Pask and Scott 1971), investigated the form of learning strategy adopted in a free-learning situation, where the student was free to focus his attention on different components of a signal translation task as he chose. Two classes of strategy were detected: a holistic, many-at-once approach, and a serialist, one-step-at-once approach, either of which could be effective.
A “conversational” teaching system was devised wherein the student’s choices were accepted only if his performance was at an acceptable level, otherwise the teaching system assumed control, basing its decisions on empirically validated diagnostic measures.
Such systems were shown to be more effective than either pure free-learning alone or straightforward adaptive machine teaching.
These studies were the inspiration for a long series of investigations of individual differences.
At the same time they helped inspire Pask to elaborate his theory of learning and teaching so as to fully allow for the student to act as his own teacher with his own descriptive framework for the structure of a skill or body of knowledge.
As already noted, these developments, in the form of conversation theory, are the main concern of Part 2 of this paper.
Part 4 – Social Cybernetics
Pask has written several lengthy papers on social systems and social cybernetics. He has taken the paradigms and findings of his laboratory work and, following the general spirit of cybernetic thought, seen to what extent their range of convenience can be extended to shed light on the larger concerns of mankind. An early paper (Pask 1966) still reads as a remarkable attempt to bring a unitary cybernetic view to bear on problems usually distinguished as sociological, psychological, political and ethical.

It was in the context of such discussions that Pask first articulated his concept of the
Psychological Individual (P-Individual) as distinct from the Mechanical Individual (M-
Individual). The concept has been elaborated extensively: in the theory of conversations proper, a conversation is a P-Individual.
The main thrust of the distinction is to recognise the systemic nature of the P-Individual as a unitary organisation which may or may not be correlated with the unitary organisation of an
M-Individual.
A typical M-Individual is a processor, such as a brain. Such a processor may execute one or more P-Individuals as processes – here Pask has in mind the internal conversation that is cognition, most clearly observed in the experimental free-learning situations where the student, acting as his own teacher, directs his own attention.
Several such processors may execute the P-Individual, which is a conversation: the social process which, by dint of information transfer, synchronises the activities of a collection of
M-Individuals.
By focusing on the organisational properties of cognitive systems, Pask is unique in having developed a set of concepts which can unify the social sciences: organisationally, a social institution and an isolated psyche are both subsumed as conversational processes, as P-
Individuals.
That Pask has done more than make loose analogies about “group minds”, I hope to make clear in Part 2, where the logical and epistemological foundations of conversation theory are spelled out.
Part 5 – The Bridge
In many ways, the paper delivered by Pask to the First World Congress of Cybernetics is a record of his finest hour. In it (v Pask 1969a), he brilliantly summarises the extent to which cybernetic thought has permeated all the biological and social sciences and goes on to specify the particular developments, chiefly conceptual, which have occurred in psychology. He identifies the current implicit metatheoretical stance and names it “systemic-monism”: the working analogy that identifies brain and mind as a unitary mechanism. He argues that this stance conceals a logical obfuscation: that there is a necessary distinction between systems whose goal is specified by a designer or observer and systems whose goals are, from the observer’s perspective, set by the system itself. The former, he identifies with the class of taciturn systems: e.g. the brain as observed by a neurophysiologist and the latter as languageorientated systems: e.g. a small group as observed by a social psychologist.
He goes on to say that we require a theory of the language-orientated system: that such a theory is, in fact, a theory of theory-building.
He calls for formal tools to extend our reasoning powers in this area and notes the promising developments in logic and mathematics made by Howard, Rescher, Spencer-Brown,
Loefgren and Holt.
How Pask himself has employed these tools for the development (and embodiment ) of such a theory is, as noted at the outset, the concern of Part 2 of this paper.

References
ASHBY W R. 1956. An introduction to cybernetics . New York: Wiley.
CRAIK K J W. 1966. The nature of psychology . Cambridge: Cambridge University Press.
CROSSMAN E R F W. 1959. A Theory of the acquisition of speed-skill. Ergonomics 2: 153-
166.
GAINES B R. 1967. Automated feedback trainers for perceptual-motor skills. Final report on
MoD Contract: “Servomechanisms in Operator Training for Tracking Tasks”, Dept. of
Experimental Psychology, University of Cambridge.
PASK G. 1958. Electronic keyboard teaching machines. J Nat Assoc Educ Commerce.
Reprinted in Teaching machines and programmed learning Volume 1, R Glasser and A
Lumsdaine (eds), Nat Educ Assn, US, 1960, pp336-349.
PASK G. 1959. Physical analogues to the growth of a concept. In The mechanisation of thought processes. A Uttley, ed. London: HMSO, pp877-922.
PASK G. 1961. An approach to cybernetics. London: Hutchinson.
PASK G. 1963. The use of analogy and parable in cybernetics: with emphasis upon analogies for reasoning and creativity. Dialectica 17: 167-202.
PASK G. 1965. Learning machines. In Automatic and remote control. London: Butterworths, pp393-411.
PASK G. 1966. Comments on the cybernetics of ethical psychological and sociological systems. In Progress in biocybernetics. Vol. 3, J P Schade, ed. Amsterdam, Elsevier, pp158-
250.
PASK G. 1968a. A cybernetic model for some types of learning and mentation. In Cybernetic problems in bionics , H C Oestreicher and D R Moore, eds. New York: Gordon and Breach, pp531-585.
PASK G. 1968b. Man as a system that needs to learn. In Automaton theory and learning systems . Ed D J Stewart, London: Academic Press, pp137-208/
PASK G. 1969a. The meaning of cybernetics in the behavioural sciences. In Progress of cybernetics, Vol. 1, J Rose, ed. New York: Gordon and Breach, pp15-44.
PASK G. 1969b. The computer simulated development of populations of automata. Math.
Biosci. 4:101-127.
PASK G. 19721a. Some mechanical concepts of goals, consciousness and symbolic evolution. Extracts cited in Bateson, C (1972). Our own metaphor, New York: Knopf.

PASK G. 1972b. A cybernetic experimental methodology and its underlying philosophy. Int
J Man-Mach Stud, 4:211-216.
PASK G. 1975. The cybernetics of human learning and performance. London: Hutchinson.
PASK G and LEWIS B N. 1968. The use of a null-point method to study the acquisition of simple and complex transformation skills. Br J Math Stat Psych. 21(1): 61-83.
PASK G and SCOTT B C E. 1969. A comparative study of adaptively controlled and other methods of instruction. MoD Contract No. A/70/GEN/9725, System Research ltd, Richmond,
Surrey.
PASK G and SCOTT B C E. 1971. Learning and teaching strategies in a transformation skill.
Brit J Math Stat Psych.
24:205-229.
PASK G and VON FOERSTER H. 1960. A predictive model for self-organising systems,
Part 1. Cybernetica 3(4): 258-300.
PASK G and VON FOERSTER H. 1961. A predictive model for self-organising systems,
Part 2. Cybernetica 4(4):20-55.
PRINGLE J W S. 1951. On the parallel between learning and evolution. Behaviour 3 , reprinted in General Systems Yearbook , 1, 1956.
SCOTT B C E. 1979. Heinz Von Foerster: an appreciation. ICNL pp 209-214.
SPENCER-BROWN G. 1969. The laws of form . London: Allen and Unwin.
WIENER N. 1948. Cybernetics . Cambridge, Mass.: MIT Press.

INTERNATIONAL CYBERNETICS NEWSLETTER
THE CYBERNETICS OF GORDON PASK
Bernard Scott
PART 2 – THE THEORY OF CONVERSATIONS
Scott, B. (1982). "The Cybernetics of Gordon Pask, part 2", Int. Cyb. Newsletter, 24, pp. 479-491.
1.
Introduction
The reader is referred to Scott (1980) for Part 1 of this paper, where Pask’s work from the
1950s to the early 1970s is briefly reviewed. Part 2 is concerned with the later work. As noted in Part 1, the many strands of Pask’s work and thought were brought together in 1972 in the form of a formal theory of conversational processes. A research program of theoretical and empirical studies ensued, the chief concerns being human learning and cognition, machine based teaching, the structure of knowledge and curriculum design, individual differences in cognitive style, cognitive versatility, innovation and learning to learn. The work was funded chiefly by the SSRC of Great Britain. Other agencies who sponsored projects included the
Ford Foundation, the Brooklyn Children’s Museum, the United States Air Force and Army
Research Institute. Descriptions of much f this work are to be found in two books (Pask
1975a, 1976). Earlier work is summarised in Pask 1975b.
The term “research program” is used, advisedly, in the sense of Lakatos (1970) to mean the creative evolution and application of new paradigms (theoretical and methodological) in scientific endeavour. In conversation with Pask, Lakatos (1975) acknowledged that his concept of a research program was isomorphic with the cybernetic concept of “a fuzzily selfreplicating process”. In Pask’s theory, a conversation is just such a process. One of the exciting aspects of being a participant in the research program based on conversation theory was the reflective awareness that one was indeed living the theory. As noted in Part 1, what made conversation theory a paradigmatic breakthrough, was its fully reflexive nature. It was indeed a “theory of theory building” (Park 1969a) and, so to speak, evolved out of itself by
“cognitive bootstrapping” (cf Chew’s bootstrap hypothesis evolved in the milieu of quantum physics, Chew 1968).
It was characteristic of Pask that the first written statement of the main tenets of conversation theory appeared in an unlikely place – the preface to a colleague’s book. Pask was invited to write the preface and did so in 1972. In the event, the book, with Pask’s short paper, was not published until some time later (v Pask 1975c). It appears that Pask was following his usual practice of never writing or lecturing without injecting a modicum of innovation. On that occasion, conversation theory had completed its gestation and appeared, terse but fullyfledged, for the first time.
It make mention of this paper, not only because I write as a historian, but also because the interested student of Pask’s cybernetics may like to compare this statement of the theory with the later (and lengthier) expositions.

Later in 1972, Pask published a short paper (Pask 1972) to serve as an introduction to a series of papers in which the full ramifications of the theory were to be revealed. In that paper, the general theme of the theory and an outline of its scope is given, but detail is suppressed.
The full statement of the theory was reserved for the third paper of the series (Pask, Scott and
Kallikourdis 1973). Pask was cautious. Well aware of the prevailing attitudes in contemporary psychology (particularly British experimental psychology) with their emphasis on empirical studies and general distrust of “grand theory”, he chose to publish two papers reporting substantial experimental work first (Pask and Scott 1972, 1973). These were generally greeted with acclaim.
Even so, in the third (theoretical) paper, Pask still took pains to exemplify the theory by constant reference to its embodiment (Pask’s term) in an artefact (CASTE – course assembly system and tutorial environment) and discussion of empirical studies of machine monitored tutorial conversations. A fourth paper (Pask, Kallikourdis and Scott 1974) dealt in detail with the sub-theory of “conversational domains” and its applications in education-knowledge structures and course design.
Eventually, the papers, with additional material, were published in book form (Pask 1975a, cited above).
Despite the painstaking manner in which Pask prepared the ground for the theory’s presentation, it is fair to say that it has not won general acceptance in psychology. The dominant attitudes were too strong. The theory (through its applications) has had far greater impact in educational circles and is recognised, internationally, as a major contribution to educational praxis.
In the remainder of this paper, I shall attempt an overview of the theory and its applications.
In doing so, I shall unashamedly reverse Pask’s cautious (and modest) way of introducing his work. Section 2 is concerned with “pure” theory. In Section 3, empirical studies and applications are briefly summarised. In the final section I essay an appraisal with additional, speculative comment on what I see as the role of conversation theory and cybernetic thought, generally, in the future developments of information technology.
2.
Conversation Theory: A Unifying Paradigm
It should be emphasised at the outset that Pask’s motivation in developing his theory was, first and foremost, to make a major contribution to cybernetics.
Although the theory is interpretable as a psychology and has been applied chiefly in education, as a cybernetic theory its scope and aims are far more general. As Ashby (1956) stressed, cybernetics “has its own foundations” and
“the truths of cybernetics are not conditional on their being derived from some other science”. These claims for cybernetics were and are controversial but if
Pask’s work is to be properly understood it must be seen as informed throughout with this same vision of cybernetics as a truly major intellectual development in Western scientific culture. Pask’s aim was not only to theorise as someone already committed to cybernetics but also to make clear, once and for all , what indeed are the foundations of cybernetics. From this perspective,

conversation theory is nothing less than a reappraisal of all extant philosophies of science and an attempt to rewrite them within the context of a formal theory of consciousness.
As noted in Part 1, a similar perspective is shared by Von Foerster. Von
Foerster distinguishes a first order cybernetics as “the science of observed systems”, and a second order cybernetics as “the science of observing systems”, i.e. second order cybernetics seeks to explain the observer to himself. This is indeed the goal of conversation theory. Writing more than a decade earlier,
Ashby noted (Ashby 1961) that his generation of cyberneticians had answered the question of “what is a brain?” He had in mind his own concept of a brain as a species of ultrastable system. He suggested that it was up to the next generation to answer the question “what is mind?” In Von Foerster’s terms, the former question is first order, the latter question is second order.
Pask’s solution to this second question is elegant in its simplicity and, as he has noted himself on several occasions, is, in essence, merely a restatement of one of McCulloch’s (1965) dictums. I will restate it here, for emphasis as a separate paragraph.
Consciousness is the knowing, with each other, by two or more participants of a relation.
Notice, this definition is not an explanation. It erects at the core of cybernetic thinking a “unit of mind” (to borrow one of Bateson’s (1972) terms, used with a similar intent) which cannot be further reduced .
As we shall see, this recognition of the limits of our powers to explain was, in
Pask’s own phrase “not a source of despair” (Pask 1969) rather it was (and is)
“an indication of the limits and fascinating potential of our discipline” (ibid).
Thus, fully aware, as few others have been of the limits imposed on pure intellect in coming to know the unknowable, Pask set out to show what could be done employing a theoretical framework which took as its foundation the irreducible nature of mind and consciousness. As I hope will be shown, the theory developed from this foundation does indeed mark a paradigmatic shift
(in Kuhn’s sense) for the behavioural sciences and, at the same time, in true cybernetic spirit brings unity and order to an otherwise conceptually confused discipline.
Let us once more refer to the definition of consciousness noted above. Two terms in it require some further commentary. The stage is then set for a presentation (albeit in outline) of Pask’s theory.

First, note the phrase “Knowing … with each other
.” Built into this “irreducible unit of mind” is the statement that all cognition is conversational in form. The concept of an isolated psyche that “knows” is meaningless. There is always a thou with the I. (Without labouring the point, Meister Eckhart, Martin Buber, C
H Cooley, G H Mead and R D Laing, among many others have come to similar conclusions with respect to the structure of the psyche). Notice the full implication with respect to the nature of the cognitive “sharing”: not only do participants “know” the same relation, there is also an awareness that this knowing is shared. As Laing and, in a different context, Howard (1971), have noted the levels of awareness may be elaborated as a hierarchy of perspectives and metaperspectives.
One of Pask’s innovations was to explicate the minimal situation in which a machine based heuristic could serve as a surrogate participant or
“conversational support” – more of this in the next section. The second phrase requiring elaboration is “knowing … of a relation”. The term “relation” is used, as a mathematician uses it, to mean pattern or order. This usage stresses the systemic complexity of all knowables. All are open to further analysis. There are no cognitive “atoms”, analogous to “sense data” or simple percepts. Again, as we shall see in more detail later, this implies a basic circularity in the cognitive domain.
The knowable, the relation in question, can be any relation, including the relation to the observer. As Von Foerster has revealed “the observer is his own ultimate object” (Von Foerster 1972).
Essentially, here we have two distinct propositions, which ultimately say the same thing. The circularity implies self-reference and vice versa. As the Hindus say “tat tuam asi”: “thou art that”.
Fortunately, our earlier commitment to consciousness as a conversational process involving two or more participants has avoided the sterility of solipsism.
Von Foerster’s formulation is an attempt to deal with self-reference directly.
Though certainly profound and full of enlightenment, the methodological apparatus that makes a proper connection between “knowing how to ride a bicycle” and “knowing oneself” is not developed. Pask’s theory supplies just such a framework and, as those who have read and understood his major work
Pask (1975a) will appreciate, the methodological concerns are painstakingly spelled out and, as already noted, explicated with reference to a system designed to allow the observer to detect the reproductive cycles called “understandings”

that demarcate distinct occasions within a conversational process (CASTE).
Pask has likened CASTE to a physicist’s cloud-chamber. It is an observer’s tool. As such it is subject to fundamental uncertainties analogous to those in particle physics. In brief, an observer of a conversation can either be certain where attention is focused by participants in a given conversational domain, that is, the intention, but be uncertain as to the temporal ordering of the occasions on which the joint understanding of a particular relation subordinate to that intention is achieved or he can be certain of the temporal ordering of such occasions of understanding but be uncertain concerning the current intention of the participants. This reflects the fact that with respect to a given intention, different relations within the domain main be addressed in parallel (holistic learning). If participants choose or are constrained to act serially (one relation addressed only on a particular occasion), information concerning more global intentions is lost.
Given that a conversation is a “fuzzily self-reproducing process”, how is it to be observed? Pask begins by considering a limiting case, referred to as a strict conversation. In such a conversation, the domain of the conversation is finite and fixed, as when a teacher and learner address a given body of subject matter.
The observer and participants have access to a description of the domain. The description is necessarily a two-level description. The lower level specifies, with respect to a canonical universe of relations, all permissible ways in which a given relation can be constructed or modelled (so-called “task structures”).
Thus, this level of description specifies the operational aspect of understanding: a particular participant has a concept for the relation insofar as he can
“recognise it, reproduce it, or maintain it”.
The higher level of description specifies the relations between relations that constrain it to be a consistent, coherent whole (a so-called “entailment structure”) and thus represents all permissible ways in which a particular concept can be derived from other concepts (in learning or remembering). This level of description specifies the comprehension aspect of understanding: a particular participant has a memory for a concept insofar as he can explain it, i.e. derive it from other concepts through a chain of explanation.
The basic reproductive cycle within a conversational process is then completed when one participant can both model a relation and justify his behaviour by exhibiting an explanation chain in terms of already understood concepts, where both his model and derivation are agreed by the other participant to be adequate.
An important feature of an entailment structure is that it includes relations of analogy, i.e. purely cognitive operations. This allows for the construction and

specification of truly cybernetic conversational domains in which (as in ecology) everything is related to everything else.
Participant
Memories
Concepts
Participant
Memories
Concepts
Level of entailment relations between concepts
Level of execution of concepts as procedures
(task structures)
Universe for modelling relations
Figure 1 – The “skeleton of a conversation”
Following Pask, the minimal framework for observing a conversation is summarised in Figure 1: the “skeleton of a conversation” (Pask 1975a).
The vertical dashed line shows the observer’s distinction between participants. The lines crossing that distinction are for linguistic (or, as Pask would say, “provocative”) interaction between participants.
The horizontal dashed line shows the observer’s distinction between lines in hierarchy. The lines crossing that distinction represent causal interaction between procedures. This avoids the notion of a procedure that acts on itself and reveals why the description of a conversational domain is necessarily two-levelled. It follows that the language by which participants communicate is also necessarily a two-levelled. In a natural language, the assignment of utterances to a particular level is often not clear cut. Pask’s insight is to recognise that all utterances have the form of a command. The fundamental command from one participant to the other is to explain (model) a relation. It the concept necessary is not available, the command is reinterpreted at the higher level as a command to learn or remember. In CASTE, all such transactions are carried out via a mechanical interface. Their interpretation is unambiguous and the observer can readily record their type and order.
It should be emphasised that concepts are program-like entities that undergo execution as procedures, which reproduce relations. Pask’s term for concepts which act on concepts is
“memories”. As such, they too are program-like entities that undergo execution as procedures. The distinction between the two types of procedure is one which is made by the observer
. Pask’s use of the term memory in this way has often caused confusion. Although it reflects the view that, in reality, cognition is an heterarchical dynamic process, it does not correspond to other psychologies (or computer science) in which the term “memory” is used to refer to a relatively passive storage medium.
In Figure 1, the universe for modelling relations is shown as external to, and shared by, the participants. This is, as it is in CASTE, where all relations are constructed using a modelling

facility. The observer can monitor and record all activities whereby the student explains concepts or receives tutorial demonstrations.
In other conversations, the “modelling facility” may be “internal”, as when carrying out mental arithmetic or other purely cognitive activities.
It is perhaps worth recalling that Pask begins with the concept of a Psychological Individual as a unitary organisation (v Section 4 on in Part 1 of this paper). Figure 1 shows the necessary constrains and distinctions made by an observer when viewing the Psychological Individual as a conversational process: the unitary-organisation is seen to be a reproductive system of memories and concepts. The conversational domain is a description of all permissible activities of the system that (for the observer) leave its identity intact. It is still the same system. Notice the subtlety of Pask’s thinking: he is well aware of the philosophical problems associated with notions of identity, particularly when applied to persons. He recognises the solution lies in applying the Cybernetic concept of a self-organising system. As noted in
Scott, 1979), Von Foerster’s classic contribution to the clarification of this concept was to recognise that when characterising such a system by trajectories in a state-space, the observer is continually obliged to revise his frame of reference as the system evolves, in effect, to invoke a potentially infinite set of such state-spaces. The true Cybernetic character of Pask’s
“conversational domains” can perhaps now be seen. They are schemata which not only are isomorphic to one of Von Foerster’s infinite series of state-spaces but which have their own organisational property – closure or “cyclicity”.
I believe these points are worth stressing. As noted later, a hierarchically organised fragment of a conversational domain looks like a Gagné style concept hierarchy or “knowledge structure” and can be similarly used for educational purposes. Indeed, the original CASTE system has entailment structures with this form, albeit with the additional possibility of representing relations of analogy between several such hierarchies.
As noted earlier, the distinctions and constraints imaged in Figure 1 are where Pask begins his account.
By successively relaxing constraints and voiding distinctions Pask brings us back to an image of the observer as solipsist, where the observing of self is the activity which allows for evolution of self.
First, the constraints on the form of the domain (initially finite) may be relaxed. The domain may be allowed to grow and be extended indefinitely.
Kallikourdis (v Pask, Kallikourdis and Scott 1975) (in the form of a computer simulation) specified the algorithm which allows for extension of a domain only if the coherence and consistency of existing concepts are maintained, that is, the algorithm treats each new concept as a hypothesis that is tested initially for its compatibility with the existing status quo of what is known and understood. If the concept is not rejected on these grounds, (coherence truth), it may (or may not!) be validated by attempts to use the concepts as a procedure for creating a new relation in the given universe of discourse (correspondence truth).
This activity is a formal model of the processes whereby progress is made in “normal science” where an accepted paradigm is applied (v Kuhn 1962).

The achievement of Pask et al was to demonstrate how, in principle, the problem-solving procedures of such a normal science can be mechanised. Understood concepts provide a schema of descriptive properties. Kallikourdis’ extend algorithm proposes new concepts whenever an empty intersection of properties is located.
Further liberalisations of the domain are:
(1) the reintroduction of self reference by allowing the domain to include self and other descriptions, including demarcations of the subdomains which are the perspectives of distinct participants,
(2) general recursion which allows the domain itself to be treated as a relation within a larger domain.
These and other purely syntactic operations on conversational domains have been embodied by Pask and his co-workers on a computer-based system “Thoughtsticker”. Software has been developed chiefly by R Newton and D Richards, special purpose hardware by R Bailey.
One particular feature worth special mention is the system’s ability to accept a hierarchical fragment of a domain and then to add the additional relations of entailment which must pertain if the fragment does indeed represent a coherent thesis. These additional relations are those which render the hierarchy a cyclic heterarchy. Once added, the user may inspect the domain from a variety of other perspectives (that is, as alternative hierarchies). These new views of his thesis may lead the user to modify it: to render his thesis more intelligible or, perhaps, to discard it in favour of an alternative approach. Thoughtsticker thus serves as an interactive medium within which to articulate a thesis as a coherent conversational domain. In the interaction, Thoughtsticker may well provoke innovation and fresh insight on the part of the user.
3.
CASTE and Empirical Studies
Descriptions of CASTE and related empirical studies are readily available in the publications cited. The overview given here will hence be brief.
Experimental studies using CASTE as a tutorial system have demonstrated its effectiveness as such, particularly in its ability to inculcate a subject matter such that every student who completes a course demonstrably has 100% understanding by any reasonable criteria and has near perfect retention of the concepts taught when tested weeks or months later. CASTE has also been shown to readily accommodate to the stylistic differences of learners, previously referred to as holist and serialist (v Pask and Scott 1972).
Essentially, there are two features of CASTE which account for these successes:
1.
the presentation to the student of an entailment structure allows all students readily to see how the course is structured and, for those who wish to, allows them to plan ahead and tackle two or more concepts in parallel.
2.
A tutorial heuristic is followed which includes a key constraint that students may not engage to learn a particular concept until such time as they have demonstrated their understanding of subordinate concepts by (a) indicating how those concepts were derived and (b) constructing models which instantiate those concepts.

The heuristic is computer-based and, in the framework of conversation theory, serves as a surrogate participant or “conversational support”. Within the constraints alluded to, the heuristic ensures that descriptions and demonstrations are given on request and maintains a complete record of all the student’s transactions with the system. In the standard tutorial mode the student:
(1) may explore any concept, that is, obtain a brief description of its content and receive information regarding how the concept may be derived from other concepts;
(2) must choose one concept as his current aim;
(3) may choose one or more concepts to work on.
These latter must be subordinate to his aim and must themselves have all necessary prerequisite entailed concepts understood. Having chosen to work on a concept, the student may request demonstrations. He is constrained to demonstrate his understanding of the concept before being permitted to change his aim or choose other concepts to work on.
As noted earlier, the chief strength of CASTE is its ability to teach effectively. The principles of CASTE tuition have been employed in schools using a non-computer based version called
INTUITION and, more informally, with small groups of students to teach concepts in genetics, reaction kinetics and probability theory. A CASTE style teaching program has been successfully implemented in the Prestel Viewdata system.
More open-ended studies have encouraged students to “learn to learn” by teaching them
CASTE principles and engaging students in Thoughtsticker style construction and manipulation of representations of subject matter.
Diagnostic tests have been used to reveal to a student his or her bias toward operation learning or comprehension learning. These studies have been well received by students and their respective institutions (secondary schools, colleges and universities). In the nature of such open-ended interventions, their overall effectiveness cannot be demonstrated with the same conclusiveness as other more formal controlled investigations of the learning of fixed subject matter. Informal feedback has been most encouraging.
Conversation theory has been applied in other contexts (design engineering, decision making). These are briefly described in an ICNL research report (Scott 1978).
Processes with beginnings have ends. The non-profit research organisation, System Research
Ltd, no longer exists. Pask continues to write, teach and consult, based partly in London (the
Architectural Association) and Holland (the University of Amsterdam). The research team is dispersed: Kallikourdis has returned to Athens, Bailey is a successful entrepreneur in microelectronics, Lewis has long been with the Open University, Mallen with the Royal
College of Art, Richards is a commercial systems analyst, Scott is currently a teacher of mathematics. The whereabouts of others is unknown. One thing is certain, all who passed through System Research Ltd, were deeply affected by their time there. Its spirit lives on in other conversations.

4.
Concluding Comments
As noted in Part 1 of this paper, Pask, again and again, has shown himself to be an innovator and visionary working ahead of his time. As such, his creations, CASTE and Thoughtsticker are perhaps best seen as sketches of an information processing technology that has yet to be, whose aims and aspirations concern not just local issues of the effectiveness of educational processes but look to the more global problems of cultural evolution and social stability.
Although CASTE has been used successfully to teach isolated theses and bodies of subject matter, Pask's motivation for creating the system was to construct a “vehicle for driving through knowledge” (see Pask 1969b, 1972b, 1973 for essays on this theme). Modern information technology is now providing the medium for such a vehicle. Viewdata systems are now becoming available to the general public as part of an international network. A new facility, GATEWAY, permits a user not only to access information stored on a Viewdata central computer but also to access an information provider’s own computing system in an interactive manner. Thus, in principle, an infinite amount of information may be accessible.
An additional feature, currently being developed by the (British) Council for Educational
Technology as “telesoftware”: the ability to transmit software directly to a user’s own local computing system.
In general, Viewdata type databases are hierarchically organised. Pask’s vision of a universally available embodiment of man’s informational and cultural heritage will become available as and when the databases are reorganised as Thoughtsticker style interrelated heterarchies. Such databases will no longer be “passive”. Heuristic routines will be called upon to continually sort and relate the concepts embodied, proposing novel relationships as a necessary by-product of their activity. The user will be invited to participate in an intelligent conversation. The system, like CASTE, will teach concepts, not merely retrieve them.
These developments may sound rather fanciful. One suspects that mankind will not selfconsciously design such a super-intelligence. Rather, it will evolve as part of man’s symbiosis with his artefacts. Cybernetic visionaries (Wiener, Beer, Von Foerster and Pask) who see both the need and the inevitable creation of such systems tend to be ignored in the generally conservative climate of political and commercial opinion and forecast. The interested reader might well seek a copy of a proposal for the explicit development of such a
“public cognitive computer system” submitted by Von Foerster et al to the National Science
Foundation (USA) (Von Foerster et al 1972). In part, the abstract reads “the basic purpose of this research is to establish the causes of the dysfunction of the interface between the individual and his society and to enhance this interface with an appropriately designed, universally accessible, interactive and cognitive machine system”. The proposal was redrafted five times before it was finally rejected.
As already noted, the unselfconscious evolution of such a universal cognitive system is proceeding. It is a growing trend for information providers on Viewdata systems to construct and make available their own hierarchically organised descriptions of selected parts of the database that augment the classification scheme provided by the managers of the system. I suspect there is already a need for a higher order description scheme that will classify the classifications. In addition, in the near future, some of the more sophisticated features of information retrieval systems will be added to Viewdata systems, including various forms of
“keyword” search. When that happens, the system will be truly “active” with a degree of autonomy concerning its own structuring. Minimally, each retrieval activity will add further

description schemes to the database. To use the classic terminology, the system will be selforganising.
As yet, it is not clear how the ideas and visions of Pask and other cyberneticians will relate to these developments. As with the impact of cybernetics generally, much will happen where those directly responsible for developing and implementing new systems and technologies are not fully aware of the intellectual roots of their innovations.
It may well come to pass that, in a generation or two’s time, a historian of cybernetics, fully at home with his generation’s information technology, will discover with some surprise that
Pask (and others) had explicitly anticipated their achievements. Indeed, it may well be our future generation’s own super intelligent system that brings an awareness of its own genesis to light, as part of a routine request from a historian user.
As a final comment on Pask’s work, I would like to return to the core ideas of conversation theory, which, although inspiring and predicting innovation in information technology, are, in fact, drawn from Pask’s reflections and meditations on awareness, consciousness and epistemology. Perhaps when mankind has artefacts which successfully cognise and converse, he will recognise his own mentation for what it is: the never ending process of describing himself and his world to himself. Perhaps then he will be led to experience with far greater intensity the nature of his own being: that which is and endures when thought has ceased, when, in the words of the Yaqui sorcerer, Don Juan, “the world stops” (Castaneda 1972). As
Pask is fond of saying, “there are unknowables”.
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