Lecturer's Précis - Dennett (1978)


"Toward a Cognitive Theory of Consciousness"

[Being Chapter 9 of "Brainstorms: Philosophical Essays on Mind and Psychology"]

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First published online 12:00 BST 27th April 2007, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 18:00 12th January 2010


1 - Introduction

Daniel C. Dennett [homepage] [click for external biography] is a professor of philosophy at Tufts University, and proposed the architecture in question in Chapter 9 of "Brainstorms" (Dennett, 1978), as part of a broader discussion of the internal organisation of the mind. It achieves three important things simultaneously. As a statement on cognitive architecture, the model he puts forward is a good example of a late-20th century A-shaped control hierarchy [for an introduction to which, see Section 2.1 of the companion resource on "Human Error"]. As a statement on mental philosophy it shows how much of the mind's organisation can be accounted for without running up against the age-old problems of phenomenal consciousness [Glossary] and subjectivity [Glossary]. As a mini-theory of speech production it shows how speech acts [Glossary] are progressively converted into communicable language.


2 - The Model

Dennett was concerned to identify the limitations of "functionalist theories" of the mind, that is to say, theories which emphasise what is being processed rather than how individual neurons might be cleverly clumping together to do that processing. He is happy to describe himself as a "functionalist" (p152), but confesses that the best available functionalist models only provide a "sub-personal" interpretation. Here is his point in full .....


"Sub-personal theories proceed by analysing a person into an organisation of subsystems (organs, routines, nerves, faculties, components - even atoms) and attempting to explain the behaviour of the whole person as the outcome of the interaction of these subsystems. [..... They] characterise relations not between a person and a body, or a person and a state of affairs, or a person and anything at all, but rather, at best, relations between parts of persons (or their bodies) and other things" (op. cit., p153).


He then drew the following flow diagram showing how he saw these subsystems (a) being organised, and (b) interacting within the resulting organisation .....


Figure 1 - Dennett's (1978) "Sub-Personal F Dennett's original]. The Control module [top, yellow] is responsible for the mind's traditional higher function. It has "executive" access to M, and can "introspect" into its contents by using flowlines "Q" and "A". The Control module also initiates requests (using the "speech act commands" shown) for PR to produce speech [Garrett (1990) provides a more detailed explanation of how the subsystems of speech production interact, if interested].low Chart": Here are Dennett's proposals for a "cognitivistic model that by being sub-personal 'evades' the question of personal consciousness" (op. cit., p154). Note the basic A-shaped structure [compare Lichtheim (1885), Craik (1945), Frank (1963), and Norman (1990)]. The Perceptual Analysis leg [lower left, blue] is responsible for processing incoming information, and in so doing makes use (a) of "a special short-term memory store or buffer memory" called M, and (b) a "problem-solving component". The PR Leg [lower right, mauve] is responsible for the production of speech to match the speech act sent to it [Dennett got the name "PR" from the "print-out" routines commonly seen in computing systems in the 1970s]. It, too, has access to M [although the flowlines were omitted from the original].


Redrawn from Dennett (1978, p155; Figure 9-1), but with additional colour coding. This graphic Copyright © 2007, Derek J. Smith.



3 - The Author's Conclusions

Dennett assesses the value of his diagram under two main headings. Firstly he points out that it reflects what is known (or can with reasonable certainty be guessed at) about the subsystems of cognition, as follows .....


"Psychologists faced with the practical impossibility of answering the empirical questions of psychology by brute inspection (how does the human nervous system accomplish perception or cognition) very reasonably ask themselves an easier preliminary question: how could any (physical or mechanical or biological) system accomplish perception or cognition? This question is easier because it is 'less empirical'; it is an engineering question, a quest for a solution (any solution) rather than a discovery" (op. cit., p161).


More importantly, though, the model also helps identify those points within the cognitive architecture where the subsystems are not enough, that is to say, where its sub-personal abilities need to be supplemented by something more powerful. He has no final answers here, but dwells on our capacity for unconscious registration of incoming information and the curiosities of our "fringe consciousness".


4 - Evaluation

Here are some points which might reasonably be made about Dennett's model, in revision point format .....





5 - References

See the Master References List