A Formal Analysis of Complexity Monotonicity

Behaviour of organisms can occur in different types and complexities, varying from very simple behaviour to more sophisticated forms. Depending on the complexity of the externally observable behaviour, the internal mental representations and capabilities required to generate the behaviour also show a large variety in complexity. From an evolutionary viewpoint, for example, [1992] and [1871] point out how the development of behaviour relates to the development of more complex cognitive capabilities. [1996, p. 3] assumes a relationship between the complexity of the environment and the development of mental representations and capabilities. He formulates the main theme of his book in condensed form as follows: ‘The function of cognition is to enable the agent to deal with environmental complexity’ (the Environmental Complexity Thesis). In this paper, this thesis is refined as follows: the more complex the environment, the more sophisticated is the behaviour required to deal with this environment, the more sophisticated the behaviour, the more complex are the mental representations and capabilities needed