When there is more than one side in a debate, an argument can be weakened by someone who is seen as stupid or a joker if they are vocal about it. This invalidates your beliefs because if crazy person also holds the same opinion and may also be misrepresenting facts, it must be untrue, and people will dismiss your factual claims.

What is this phenomenon called?

Also what is the person called who does this? I should mention there is a specific term, and it's on the tip of my tongue but I can't quite remember!


  • This sounds like a cognitive bias. I looked here, but it's a long list. Oct 20, 2015 at 14:08
  • Group attribution error may work for what's happening in the situation. Doesn't answer the question, though. Oct 20, 2015 at 14:16
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    In certain contexts it might be a stooge. Especially if they are placed there expressly for that purpose. Maybe you could give us a more specific context - what situation do you have in mind? Do you have a real-life example? Oct 20, 2015 at 14:20
  • A stooge is getting closer to what I want, but it's not quite it. I can't think of a real life example, but here would be an example scenario: Person A is arguing for evolution and is making rational arguments based off science etc. Person B is arguing against evolution. Person C, who as a placeholder, we will call 'the stooge', is a vocal supporter of evolution. However they are, say a Paris Hilton-type and frequently misrepresents the facts, weakening the argument for evolution by making it seem a crackpot, ill-informed belief. Sorry for the terrible fake scenario I just thought up then. Oct 20, 2015 at 14:32
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    'Harmful supporter' is the closest so far, but not quite. I appreciate everyone's responses so far! Oct 21, 2015 at 9:09

1 Answer 1


He sounds like a bloody liability:

A person or thing whose presence or behaviour is likely to put one at a disadvantage. (-- Oxford Dictionaries Online)

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