These systems are not able to step out of the range of this knowledge space because they are not able to adapt their behaviour when unpredicted events occur. He also believes that the AI systems that are built must be tested, or embodied, within concrete environmental settings. The functional approach requires too many steps between when the world is sensed to when an action is produced. With the behavioural approach the sensors are much more closely linked to the actuators so the agent is able to be more reactive to changes in the environment. Dynamics as opposed to symbol manipulation is the basis of the designs.
Nature is continuous but a symbolic description requires the world to be discretised.
Their hypothesis is that the behaviour systems should dynamically interact with the world and not translate to a discrete representation where information is lost. The dynamic interaction of the behaviours are capable of producing more complex emergent behaviours. By creating simple behaviours we can allow them to interact and produce more complex behaviours that would be difficult to model explicitly. The subcognitive layer monitors the sensory inputs. The input values are communicated to the cognitive layer which decides on which actions should be activated.