exception that proves the rule

The phrase "exception that proves the rule" is an idiomatic expression that suggests that the existence of an exception to a general rule or principle actually serves to confirm or validate that rule. It means that the presence of a particular exceptional case highlights the existence or operation of a general rule in the majority of situations. In other words, when an exception is acknowledged, it reaffirms the general principle in question. However, it's important to note that the phrase's usage can sometimes be misunderstood or debated depending on the context and interpretation.