Segal's law is an adage that states:
A man with a watch knows what time it is. A man with two watches is never sure.[1]
At surface level, the adage emphasizes the consistency that arises when information comes from a single source and points out the potential pitfalls of having too much conflicting information. However, the underlying message is to question the apparent certainty of anyone who only has one source of information. The man with one watch has no way to identify error or uncertainty.