knowledge market are suitable only for knowledge augmentation, not substitution, because the knowledge is not validated or developed, and reuse is ad hoc. In this case, knowledge substitution is an impractical goal. Markets are also best suited to knowledge with long life spans, where change are slow and continuous. Markets have little central planning, so the agents in a market react to minor changes in the environment autonomously, and the knowledge evolves naturally to reflect the change. A market does not respond well when knowledge has a short life span.