The relationship between collective knowledge systems and individual knowledge is a tricky one. In any direct sense all there is individual knowledge, since there exists no collective mind or collective consciousness. Individuals learning a cultural or linguistic system, we keep trying to construct a representation of it in our minds that allows us to generate acceptable performance and judgments, and that enables us to make sense of the messages and behavior that we experience from others. The flexibility and variability that we find among individual representations of collective knowledge structures are important to the functional adaptation of these structures to the needs of their holders. The constraints of intergenerational communication and effective inter-generational cooperation are important factors in keeping most words or other collective concepts from changing too rapidly.