Description: Asserting that those who disagree with you must be wrong and not thinking straight, primarily based on the fact that they are the opposition.
Person 1 is asserting X.
Person 1 is the opposition.
Therefore, X must be wrong.
President Trump said that he was proud of the children who participated in this year’s Special Olympics. Those kids are a bunch of losers.
Explanation: This is an extreme example of a very real example that we have all seen since around early 2016. Those who passionately hate Trump, reflexively disagree with everything he says and does, associating the truth of his statement with the feelings they have for him. This is not reasonable thinking.
The Democrats support more aggressive gun control laws. Can you believe they want to deny repeat offenders and those on the terrorist watch list their rights?
Explanation: Very often we see support for reasonable policies rejected based on the party that proposes such policies. We know this because research has been done in this area.
Exception: There might be a situation where your opposition must say things that are demonstrably wrong, or they wouldn’t be your opposition. For example,
Only those who disagree with X are my opposition.
X is demonstrably right.
Bill is my opposition.
Therefore, Bill is wrong.
It seems strange to suggest that because Bill is my opposition, he is wrong, but this is necessarily true if we hold that “Only those who disagree with X are my opposition” and “X is demonstrably right.” This wouldn’t make logical sense if we didn’t set the conditions so that anyone belonging to the group “opposition” would be wrong.
What Now: Rejecting information from an opponent known to lie, might be a reasonable heuristic, but it is not a good critical thinking technique.
This a logical fallacy frequently used on the Internet. No academic sources could be found.