Guilt by association

Photo taken at Fort Breendonk, Belgium, a former fortification,
 which  served as a Nazi prison camp during World War II

It occurs so often that actually everybody should know that it is a fallacy: Guilt by Association (GBA). Nevertheless, “this fallacy permeates society, from social groups, to political campaigns, to business relationships, to the court system”, as Leigh Kolb writes in his article about the fallacy. This is not an innocent matter, for throughout history, guilt by association has made people justify persecution, discrimination, and social ostracism. But what is guilt by association, or, as it is also called, the association fallacy?
I found a clear description in an article by Joshua M. Bentley, which I have adapted here a little bit: Guilt by association is the phenomenon that occurs when one party, person or thing is distrusted because of its connection to another party, person or thing that has done something wrong. Guilt by association is a kind of heuristic, or mental shortcut, that people use to decide which companies share their values, viewpoints, ideas, and the like. This is the negative version of the fallacy. There is also a positive version, which I’ll ignore. (You get it by replacing the word “wrong” by “good” here). I’ll also ignore GBA for things. Guilt by Association is related to the idea of identification, because people are identified with (associated with) members of the group(s) they belong to and share ideas and views with, and/or with individuals who have the same views etc. However, the problem is that the person or persons involved are not only associated with others because of the views etc. they share but because of this association they are also often ascribed the views etc. of these others that they don’t share or that they have never commented on. It’s something like: Show me your friends, and I'll show you who you are.
In formal terms, the reasoning in GBA is this from Wikipedia):

                    Premise (1):    A is in set S1
                    Premise (2):    A is in set S2
                    Premise (3):    B is also in set S2
                    Conclusion:    Therefore, B is in set S1.

But the conclusion doesn’t follow from the premises, which makes Guilt by Association a fallacy.

First some simple, if not banal examples (again from Wikipedia):

- John is a con artist. John has black hair. Therefore, people with black hair are necessarily con artists.
- Lyle is a crooked salesman. Lyle proposes a monorail. Therefore, the proposed monorail is necessarily folly.
- Simon and Karl live in Nashville, and they are both petty criminals. Jill lives in Nashville; therefore, Jill is necessarily a petty criminal.

I think that you’ll immediately see from these examples how fallacious the GBA is. However, many cases of GBA are more difficult to recognise and less “banal”. Therefore, people often fall into the GBA trap, and commit them themselves. For isn’t it so that associations can also be true? But often they are not and therefore we must always check them. Nevertheless, many times people apply them without checking, because for them the associations seem obvious, though they aren’t.
Even worse are the cases that they are used by politicians in order to manipulate their followers or to attract new followers (and maybe they even believe them themselves). Let me give a few examples of possible dangerous consequences of the Guilt by Association fallacy, leading to suffering by innocent people. Maybe the best-known case of GBA is the McCarthy era in the United States: Senator Joseph McCarthy led a campaign against alleged communists in the government and other institutions. Individuals suspected of having communist sympathies were subjected to intense scrutiny, harassment, and even imprisonment. Many innocent people lost their jobs, careers, and reputations as a result of these unfounded accusations, simply because they were said to have ideas (rightly or wrongly) that were considered “communist”, despite their actual behaviour. (see Bentley) What also often happens is that individuals associated with certain religious or ethnic groups are discriminated against in the aftermath of terrorist attacks, for example after 9/11. Or, – another case – when in 2002 a populist Dutch politician was murdered by an environmentalist, not a few reacted by saying “the bullet came from the left”, as if most people with leftist ideas would support this murder and were responsible for it. This is also what we see now in rising authoritarian states. More and more people there are harassed, dismissed from their jobs, if not held responsible for a political murder, if it happens, simply because they use the democratic right to oppose “the leader” and to disagree with his ideas. But people are only guilty for what they have done and not for possible or alleged associations with perpetrators. If this happens, we have a case of Guilt by Association.