All entries for Sunday 21 August 2005
August 21, 2005
Despite some interruptions, I'm now up to chapter 8 of Andy Clark's Being There. The chapter on The Neuroscientific Image presented a plausible model of cognition based upon brain research, but combining functional-hierarchical, distributed, embedded and dynamical approaches. But I am still not satisfied that the question of methodology is addressed sufficiently.
The important point is that dynamical and computational explanations are not exclusive, but rather, describe actually distinct forms of organisation and mechanism, and hence our task is to identify when one or the other is more appropriate (and indeed the combinations of the two).
That is good, but rather than giving a systematic guide as to how we can apply these various approaches, we instead see a cognitive 'science' built upon a patchwork of interdependent conjectures concerning the many distinct aspects of embedded and evolutionary cognition. The conjectures add up to an 'engineering model' of the intelligent organism, with the aim of offering a plausible story. They concern, amongst many other aspects:
- Components available for the construction of the system, and the energetic and physiological limitations imposed on those components (both in the brain and the rest of the body);
- The ontogenetic generation and regeneration of those components within the life of the individual, in isolation and through complex co-evolutionary relationships;
- The diversity of the modes of organisation of those components, and their interactions (including either computational and dynamical operations in combination);
- The generation and regeneration of those organisations;
- Components in the environment available for simplifying and extending cognitive processes;
- The feedback and feedforwards loops between these internal processes and the external environment within which the organism is embedded;
- The limitations and requirements (temporal, spatial) imposed upon the individual by the environment;
- Co-evolutionary links with other complex entities in the environment of the organism;
- The phylogenetic development of all of the above in the evolution of the species and its environment.
But how can these individual conjectures be 'falsified'? Much of the work of cognitive science is to assess the fit of one of these conjectures with the many others. Of course that may lead to complex but consistent theories that seem plausible but which turn out to be entirely wrong. What other means do we have for assessing the plausibility of the conjectures. Clarke relies on two:
- Selective neural damage evidence – the mainstay of neuroscience, showing how damage to a part of the brain has specific effects on behaviour;
- Economic plausibility – assessing whether a conjecture describes mechanisms that are just too extravagant and costly to be likely (for the individual, species or environment).
Method 1 is relaible where a theory depends upon the existence of a localized centre of mental functionality or control that is suspeptible to damage. However, even in these cases there may be important distributed and dynamical elements that are difficult to assess (and hence get ignored by the theory).
Clarke gives some relatively trivial examples of method 2. However, I am not convinced that such 'economies' of resource (including time) are often simple or stable enough for easy analysis. And furthermore, if we consider the organism not to be an individual, but rather to be an assemblage of highly mobile components (especially at the 'higher' levels, at which an individual may become possessed by powerful, nomadic memes driving its behaviour), economies become much less predictable and reducible.
More fundamentally, i'm not at all convinced that there is some 'rule of efficiency' driving and limiting all phenomona. That I think is the really interesting question.
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