3.6 The organism as a cognitive system.
The behaviour of a particular cell is meaningful in the context of the field it finds itself in. Lens formation is useful only within the context of the eye. When a cell has finally differentiated into a transparent fibre as part of the refracting body of the lens, it can be said to have generated a useful representation of a property of light: by refraction it projects a part of the perceived world on sensory receptors. This property has found a meaningful representation in the developing organism. Such a useful representation of a relevant part of the environment in an organic form and in an appropriate function can be called knowledge (Goodwin 1976). Organisms are cognitive systems that have collected their knowledge in the course of evolution. In other words: cognition is expressed in adaptive development of form and behaviour.
This chapter has been largely a summary of Goodwin's views and has been free of mathematical descriptions. The reader should know however that theorists, such as Zeeman, Eigen, Haken, Grossman, and also Goodwin himself have developed mathematical models of what I have been explaining verbally. Like other area's of science, theoretical biology is well served by the interaction of mathematical modelling and the actual observation of reality.