Guilt By Association

(Ad Hominem) Guilt by Association seems to have 2 variations:

1).  A makes claim X

B responds by asserting that A associates with (or is a member of) Z, some person or group that is disfavored and/ or despised.  Therefore A is not credible and X is false.

Ex:   Candidate A is a follower of Z, a racist so anything A says should be disbelieved.

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2).   A makes claim X.

B responds by asserting that Z (some person or group that is evil and/ or despised) also believes or supports X.   Therefore, (since bad people believe X), X is false.

Example:  Candidate A believes in state’s rights, as do most racists.  Therefore state's rights should be shunned.

Are these two different fallacies?   The thrust seems different.  The first version is related to Appeal To Spite, although Appeal To Spite isn’t necessarily an Ad Hominem attack.   The second seems more like an inverse of Appeal To Common Belief   (if a negative source believes something, it's false).

They both discredit a source based not on its own merit, but what it is 'associated' with.

The first one suggests that because source A is associated with disfavoured group Z, A is not credible. The association of A with Z is used to critique A, not A itself.

The second one suggests that because A says X, and disfavoured group Z also says X, X is therefore false. That is, A and Z are 'associated' by believing the same thing. (The assumption being that if a disfavoured group says something, it is necessarily false. This does not follow.)

They're different versions of the same fallacy to me.

To commit the ad hominem (guilt by association) fallacy, one would discount a source or an argument simply because that source or the advocate is associated something already viewed negatively.

In your case 1, B claims that X is false.  When asked why, it seems B would say something like, "A claimed X was true. I view A negatively, therefore I see whatever A says as incorrect."  B rejects A's claim because he sees A as being associated with something else negative.

In your case 2, B claims that X is false.  When asked why, it seems B would say something like, "Both A and Z claim X to be true. Since I view Z negatively, what Z says is not correct."  B rejects A's claim because of Z's association with something else negative.

Each case seems to be one of rejecting a claim because "bad folks" support it.  Each is an example of ad hominem (guilt by association) ... the argument doesn't rest on anything related to what Claim X is ... just on who's making or supporting it.

 When a statement is challenged by making an ad hominem (Guilt by Association) attack on its author, it is important to draw a distinction between whether the statement in question was an argument or a statement of fact (testimony). In the latter case, credibility may be crucial. Ad Hominem is not always invalid if the credibility of the person issuing the statement is of importance to its conclusion.

The main thing to keep in mind is the distinction between argumentation and testimony. The whole point of logic is to develop techniques for evaluating the cogency of arguments independently of the arguer's identity. Is the person being criticized arguing or testifying? Are reasons being presented, or must we take the person's word for something? If the person is arguing, the argument should be evaluated on its own merits; if testifying, then credibility is important.”