Dennett development and design

In order to examine this we need to start by explicating the meaning of the term 'design'. We will follow Dennett in considering a non-biological example, but one that is adapted to a rather more extensive range of conditions than the chess-playing computer, the aeroplane. The term 'design' refers to a number of features of construction and operation. Firstly it refers to the objective of the construction of the object, namely that it should be able to fly. Just as in the biological examples this leads immediately to criteria for normal or correct design and construction and to criteria for mistakes. Secondly it refers to the means by which this will be achieved, and therefore to the functioning served by components and their intentionality. Thirdly it provides a specification in relation to the environment. Here this might include temperature, wind speeds, height of flying, and length of runways. The physical construction can be judged only in relation to these environmental demands. Fourth, the design refers to what goes in at the outset, in the construction, and remains constant. It therefore provides a reference point against which any particular event can be judged. Fifth, it has a high degree of generality in that it covers most or all of what the aeroplane is up to. We can see that in many respects this analysis conforms with that implied by Dennett's chess-playing computer. Nevertheless the complexity of the computer may obscure the extent to which its functioning is defined very narrowly. Its relationship to the environment is defined by a keyboard input and by an agent that understands the rules of chess. This is in marked contrast to the range of environments that might be encountered by the aeroplane, or indeed by a biological organism. Dennett's example does not contradict this, but it may obscure it, and it is crucial at this stage to bring out the relationship of'design' to complex environments.

How might the concept of'design' stand up in relation to human psychological functioning. We can examine this using the 'method' used so far in the book. We first require that it works in non-psychological biological examples on the grounds that it must work here if it is to succeed with psychological functioning, and then in relation to the observation that psychological functioning is subject to development during which there is a complex interplay between person and environment. This will lead to a consideration of design in relation to multiple sets of rules, and the generation of these within human functioning.

Taking examples from previous chapters, the term 'design' could be applied to the cardiovascular system, the genetics of protein synthesis, or the visual system. In each of these it would refer to the purpose of the system, and to the means by which it is achieved. The means would include the specification of the rules, and the convention and agreement within the signalling and control systems. As we have seen earlier the environments of the cardiovascular system and the DNA are the milieu interieur which have further links with the external world, and that of the visual system is the external world. The example of haemoglobin and sickle cell disease provided an illustration of the intimate relationship between structure, function, and environment in the definition of 'correct' or 'incorrect', and these could all be taken to be aspects of 'design'. As in the example of the aeroplane the 'design' of these biological examples will often refer to what is there from the start, and what remains constant, although in more complex perceptual systems this may not be the case. Finally the design can be taken to refer to the functioning of the system in general. It would seem then that the concept of'design' will apply to many biological systems, and it is entirely compatible with our analysis of intentional causality

The position is rather different when we come to development and multiple sets of rules. How are we to interpret the notion of what is 'hard-wired', stable and general? Take first the issue of wiring. In human development, in contrast to that of other organisms, the neuronal connections of the brain develop substantially after birth (Changeux 1985). Evidence from animal experiments, where post-natal neuronal development is more limited, indicates that neuronal connections are influenced by experience. Hubel and Wiesel (1962) showed that cats or monkeys that have been reared with one eye sutured closed have no vision in that eye and there is shrinkage of the area of the lateral geniculate body devoted to that eye, with a corresponding diminution in the number of branches sent by the deprived cells to the cortex. At the cortex there is a shift in the number of connections from the deprived to the non-deprived eye. This effect is seen only following monocular deprivation in the first three months of life, and after that age, even extended periods of deprivation seem to have little effect. Furthermore the effect of environment on neurodevelopment can be quite specific. Blakemore and Cooper (1970) showed that kittens raised in environments in which there were only horizontal stripes are blind to other orientations, and this is reflected in the preferential responses of neurones in the visual cortex. Human infants show a loss of visual capacity in an eye that has been subject to 'monocular deprivation' for instance where there is a squint. It is probable this is accompanied by similar brain changes to those demonstrated in cats and monkeys. It seems therefore likely that given the greater level of post-natal development of neuronal connections in humans during the first years of life, there may be a similar process whereby connections that are required for a wide range of psychological functioning are influenced by environmental experiences. Wiesel (1982) wrote

'Deprivation experiments demonstrate that neuronal connections can be modulated by environmental influences during a critical period of postnatal development. We have studied this process in detail in one set of functioning properties of the nervous system, but it may well be that other aspects of brain function, such as language, complex perceptual tasks, learning, memory, and personality, have different programmes of development. Such sensitivity of the nervous system to the effects of experience may represent the fundamental mechanism by which the organism adapts to its environment during the period of growth and development.'

This speculation has been amply supported by subsequent research. Studies of the effects of early post-natal separations on the regulation of cortisol in rodents have shown that persistent alterations in neuroendocrine can be caused by discrete periods of maternal separation (Sanchez et al. 2001). Furthermore these alterations are accompanied by behavioural changes. Huot et al. (2001) found that early post-natal separation was associated in rats with later preference for alcohol (ethanol) mediated via altered corticosteroid responses to stress. The mechanisms are complex and are likely to involve gene expression, and altered density of neurones in structures such as the hippocampus. It seems then that the wiring might be influenced by organism-environment interaction through a process that is similar to learning. If we are to retain the concept of design, we will at least need to talk of a succession of designs each related to but different from the previous one, and we will need to understand the relationship between them, and the environment.

The question of stability brings us back to the generation sets of rules and expectancies, and their role in providing the basis for action, and further testing of the rules in development. Theories of the development of intimate (attachment) relationships and of cognitive development have emphasized the interplay between internal mental models or schemata, and experience, whereby sometimes new evidence may be incorporated into existing schemata, and at others may contribute to the development of new ones. The implication is that the internalized general models will be more or less stable depending on (a) the extent to which they are tested, (b) the extent to which experience supports or undermines them, (c) the extent of the person's need to hold on to them for instance in order to maintain the basis for actions, and (d) their general utility. We will refer to points (a), (b), and (c) extensively in the next chapter as they provide an important basis for further considerations of disorder. However we should note here, and will return to the point, that (d) has a resemblance to that made by Polanyi (1958) and Popper (1969) in relation to beliefs in the sciences. Theories or 'laws' will be held strongly and persist, even in the light of contradictory evidence, if their wider utility is great and there is nothing to replace them; indeed one might argue provided they are effective in directing further action (see also Chapter 1.3.1 and 1.3.3). So that we can say at this point that the candidates for the persistence of sets of rules or schema, especially those with great generality, may relate to considerations other than those of whether they are wired in.

The developmental story leads to further inroads into the straightforward concept of 'design'. Development clearly entails the generation of succeeding sets of rules, schemata, cognitive-affective models, and ways of interpreting and feeling. Developmentalists of diverse origins, including Freud, Klein, Erikson, Piaget, Kagan, Bowlby, and Stern, have all postulated such successions. Each has striven to articulate the differences in general frameworks within which children operate at different phases of development, and to provide an account of what links these. Whilst not opposing this proposal, Rutter and Rutter (1992) have argued that in development the identification of what constitutes a continuity or discontinuity is not straightforward. Thus the emergence of a butterfly from a chrysalis preceded by a caterpillar is clearly in many respects a discontinuity, but in that the information for the butterfly is already present in the caterpillar this is a continuity. Indeed it must be assumed that the design information for the butterfly is present in the caterpillar. Similarly the child may take one set of expectancies from an environment in which they were appropriate to one in which they are not. What might be generated then is a different set of expectancies and behaviours, that can be understood best as the outcome of the interactions between the previous ways of seeing things and the current environment. Where then does this leave the concept of design? Either that it will have to be reserved for those aspects of psychological functioning that are not subject to such changes, or it will be necessary to talk of successive designs. Our analysis must however go further in relation to multiple sets of rules. The chess-playing computer is just that until a further design feature is built it. But what of the chess-playing human being? Strikingly he or she can perform that function for a relatively brief period, and simultaneously perform other functions, such as that of being a parent. Indeed, a feature of the behaviour of young children in play is the way they experiment with different 'designs'. Clearly it would be possible to subsume this under the overall description of a 'playful child' that might then be referred to in terms of the design. However, clinical experience suggests that if such a child were to experience a major trauma his/her play might decrease quite dramatically. Would we then refer to a 'new design' or revise the design to be 'playful child, sensitive to trauma'. The point is that in development and in maturity human psychological functioning operates under a range of sets of rules, schemas or assumptions, all of which have some of the features attributed to design in machines or non-psychological biological systems. However they vary in the extent of their generality and stability.

In summary it seems that the concept of'design' can provide a useful shorthand, and we will use it, together with the caveats reviewed here, in relation to examples of disturbance. However the analysis presented earlier provides a different emphasis. It suggests that although rule-bound responses probably evolved in ways that have clear survival value, inherent in the use of rules there is a creative potential whereby goals and activities can have their own intrinsic value. In other words if it is possible to see the same thing in many different ways, then those different ways of seeing may become the focus of interest, for instance in play. This is not to propose a mechanism but to point out that the freeing of sets of rules, assumptions, or ways of seeing, and of the accompanying emotional states and behaviours from being hard-wired, has potential for the elaboration of goals that might not be essential to survival. Once psychological states are conceptualized in terms if rule-bound processes there is no prediction as to whether or not they are wired in, or to the extent to which they are the outcome of an interaction with the environment. Similarly there is no prediction as to their stability or generality. They may be hard-wired and stable in the case of physiological and some psychological processes, or patterned in ways that are open to change. They may have great generality, or they may be quite specific. Thus it may be more valuable to talk of sets of rules governing internal models of relationships, beliefs, or patterns of emotional response, that have greater or lesser degrees of generality, are related to a greater or lesser extent to previous experiences, and are more or less stable.

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