Difficulty of creating systems

Good blog post about the difficulty of creating systems, especially the unintended consequences of creating complex and rigid systems. In this case, the post is about creating a point system for a merit/demerit system. He summarizes his thoughts in three points:

1) Modeling system effects is hard.
2) The more complex the system, the more variables.
3) The more variables, the more interactions, reactions, and unintended consequences.