argumentum ad hominem
(also known as: association fallacy, bad company fallacy, company that you keep fallacy, they’re not like us fallacy, transfer fallacy)
Description: When the source is viewed negatively because of its association with another person or group who is already viewed negatively.
Person 1 states that Y is true.
Person 2 also states that Y is true, and person 2 is a moron.
Therefore, person 1 must be a moron too.
Delores is a big supporter for equal pay for equal work. This is the same policy that all those extreme feminist groups support. Extremists like Delores should not be taken seriously -- at least politically.
Explanation: Making the assumption that Delores is an extreme feminist simply because she supports a policy that virtually every man and woman also support, is fallacious.
Pol Pot, the Cambodian Maoist revolutionary, was against religion, and he was a very bad man. Frankie is against religion; therefore, Frankie also must be a very bad man.
Explanation: The fact that Pol Pot and Frankie share one particular view does not mean they are identical in other ways unrelated, specifically, being a very bad man. Pol Pot was not a bad man because he was against religion, he was a bad man for his genocidal actions.
Exception: If one can demonstrate that the connection between the two characteristics that was inherited by association is causally linked, or the probability of taking on a characteristic would be high, then it would be valid.
Pol Pot, the Cambodian Maoist revolutionary, was genocidal; therefore, he was a very bad man. Frankie is genocidal; therefore, Frankie must also be a very bad man.