8. Not all Theories on Earth are True

First Proof

A quick search on Google tells you that factories employ a lot of workers.

Since man must eat, a factory boss might not have enough resources for his research and thus publishes half true results.

Second Proof

This occurs in mathematics exams: a student solved a mathematical problem and was sure of his answer. But when the teacher marks the student’s answer, he finds something wrong from the reference books the teacher used.

Furthermore, it is usually common for a student to have gotten three steps right while missing a single step. And this single step would make his final result wrong.