Monitoring Is Insufficient

How about monitoring?
- Watch the agent to make sure they do the right things.
- E.g., proctors in an examination, foremen in a work crew.
This works for well-defined tasks ("write the examination without referring to cheat-sheets), but not for complex decision-making.
Does not scale. Suppose the principal owns two factories -- then she must delegate monitoring, which is a relatively complex activity.
- Proctors and foremen are agents!