Belief Bias
We judge an argument’s strength not by how strongly it supports the conclusion, but by how plausible the conclusion is in our own minds.
ExampleSally mentions a theory that supports your conspiracy theory, which you adopt wholeheartedly despite the fact that she has very little evidence for it.
What to doTest the argument with a conclusion you dislike. If the same logic would convince you there, it is the logic you are judging.