We've all been in these situations, and it's pretty nasty. So here are some pointers that should help you in deciding when to run away. Not an exhaustive list by any means, but should give you a good idea of what to look for.
1) Emotional Instability
1) Emotional Instability
Responding with too many LOLs, hmmmphs, huh!, doh!, LMAOs and expletives. They can't process logic and reasoning. Their brain simply rejects rationale, and finds solace in these outbursts.
Example - Genetic research and biological studies have shown that we are only a pair of chromosomes away from the big apes. Response - LMAO..ROFL!!, I can't help you if you believe that.
2) Rogue-like Behaviour
If you corner them with solid evidence/logic on one topic, they start talking about something else, enter hibernation mode or simply shut down.
Example - Research/studies show that African Americans and Mexicans commit most crimes in the US, it needs to be addressed. Response: You're a racist and Sikander ne Porus se ki thi ladaayi! and now I'm off to sleep. (Okay, bad example, but you get the picture)
3) Comprehension Disorder
This is a pretty severe disability; they can't tell an analogy from a direct comparison just as they cannot tell their head from their posterior.
Example - The Muhammad Ali vs Joe Frazier Fight of the Century was like watching a Pitbull vs Wolf fight. Response: Huh! You’re a bigot, did you just call liberal African Americans dogs?
4) Logical Fallacies (This is THE most important, so I'll be thorough with it)
A. Ad hominem - Attacking the other person rather than countering the claims or conclusions.
Example - There is substantial evidence that divorce/dowry/violence laws are gender biased and susceptible to misuse. Response: You're just a misogynistic pig who hates women.
B. Ad ignorantiam - They just love this. They know it is right simply because you can't prove it is wrong.
Example - Watch any religious fanatic go on and on about "intelligent design" and what not.
C. Association/Causation/Coincidence/Effect – They get these jumbled up and can't differentiate between them. Reversal of cause and effect..Treating coincidence as a predetermined effect...Intentionally reducing a wide set of possibilities to only one or two.
Example - Watch any gender ideologue go on and on about Patriarchy and how anything and everything that happens in the world is a carefully thought out evil scheme.
D. Authority - Speaking from authority is a frequently used tactic. Using “he said so/she said so” as the base of an argument.
Example - Mrs. X said so in this article, I'm saying the same, therefore I'm right and you're wrong. Mr. Y said the same thing in an interview, therefore I'm right and you're wrong.
E. Analogical Fail - Another thing they cannot seem to resist. They have this habit of comparing people, things or situations which are not analogous at all. Even if by a stroke of luck they do find something analogous, it will almost always be inconsequential to the argument.
F. Broad Strokes - A very important tool in the hands of religion apologists. Basically, because two things are more similar than dissimilar, therefore both are the same.
Example - All religions teach peace and compassion.
This is actually a pretty creative ability they seem to possess. You must be wondering how I came up with such a filthy term. Allow me to explain - you see, they have this peculiar knack for mentioning "facts" and "stats" conjured out of thin air. And as we discussed earlier, about their inability to tell their head from their posterior, it becomes pretty clear where these smelly facts erupt from.
Example - Anytime someone's throwing 9 out of 10, 8 out of 10 or any other bogus statistic without evidence.
6) Blatant Hypocrisy
Thaali ka baingan as they say..changing their tune every minute to suit their argument.
Example - We should have secular Government and Laws. Response –Yes. Then we should also get rid of caste/religion/gender based laws and policies. Response - No, because oppression, because minority, because penis.
7) Playing the Victim
The hallmark of an idiot. They twist honest/direct approach into personal attacks and proclaim the argument is over and they've won.
Example - That thing you quoted is a total fabrication. Response: Did you just call me a liar? How dare you! You lose, I win.
Usually, a tactic used as the last resort, but may surface earlier. "How can you say such things to me?", "I never knew you were like this", "I'm scared of you now", "I'm disappointed in you", basically anything to appeal to your good nature to make you bow out.
So, what do you do? Usually, it's advised that you excuse yourself as soon as you see things mentioned in the first point. Although you may take your chances by going as far as number 4 or maybe even 5, depending on how well you think you know the person. But, do NOT let it go any further, under any circumstances. Not only will you be left with a very bad taste, you may very well lose some of your own IQ points.