Which fallacy is being used when someone dismisses entire groups based on a singular negative experience?

The correct answer is Hasty Generalization. This fallacy occurs when someone makes a broad conclusion based on insufficient or unrepresentative evidence. In the context of dismissing entire groups based on a singular negative experience, it indicates that a person is extrapolating their personal experience—perhaps a single negative interaction—to all individuals within that group. This reasoning lacks a comprehensive analysis and fails to consider the diversity and potential variation among members of the group, thus leading to an overly simplistic and often inaccurate conclusion.

In essence, hasty generalization highlights a misuse of evidence, where one instance is incorrectly generalized to represent an entire population, which is not justified by the evidence at hand. This underscores the importance of cautious reasoning and the need for a broader, more nuanced understanding of groups before forming judgments.