The fallacy occurs from your lack of evidence. As I pointed out.Cheeze_Pavilion said:The fact that someone is a pathological liar is only one way to impeach a witness with a justified ad hominem attack.Thanatos34 said:By all means, ignore my point to engage in yet another ad hominem attack. I specifically said that if you had proof, then I would answer it, yet you ignored this entirely to post exactly what I had just said.
In your example, you would have to know that John is a pathological liar.
Another way is to show someone has bias [http://books.google.com/books?id=NUiqfszTvV0C&pg=PA22&lpg=PA22&dq=bias+ad+hominem+testimony&source=bl&ots=S37QkfDCYi&sig=KYi8qYKugUprbUAeiYW9yvf_Xng&hl=en&ei=91MKSti_A4mmM_OxhdoL&sa=X&oi=book_result&ct=result&resnum=1]. That's why I said you were a homophobe: a homophobe is biased when it comes to issues of homosexuality. Hence the relevance and the lack of a logical fallacy.
As well as your consistent failure to produce such evidence.
Apparently you are incapable of drawing a logical conclusion from my example, as follows:
You must know John is a pathological liar to call him on that issue, so you must know I am a homophobe to call me on this one. That was my point, and since you don't know me, and you have entirely zero evidence for calling me one, you are no longer debating, you are merely being an ass.
Also, now that I think about it, proving someone has bias is a bullshit argument. By the same logic, one could say that a pro-gay person is unqualified to state their opinion on such an issue, or unqualified to be listened to, because they are biased towards homosexuals.