"The Exception that Proves the Rule"

This is a concept that explains things that might disprove someone's theory or observation. For example, a person might say, "Only skinny women can be popular in Asian culture." If someone mentions 沈殿霞, the person might respond, "Oh, she's the exception that proves the rule." (In other words, she is so unusual that, although she breaks the rule, she shows how accurate the rule seems to be. This case also explains the idea of "tokenism".)

Another example: "Only soccer players, baseball players, or basketball players can be famous all over the world." "What about Tiger Woods, the golfer?" "He is the exception that proves the rule."

Is this a useful idea? Explain how it works. Give some examples in addition to the examples that I provided.