Argument From Social Identity
Let's say you want to argue with someone over the merits of a proposition. But it turns out, you can't get your interlocutor to consider the merits of the proposition. Instead, they just tell you you're a Bad Person. The corresponding assertion, that they are a Good Person, is implied if not stated outright.
This is the argument from social identity. To your interlocutor, the merit of the proposition is not inherent in the proposition itself, or in its ramifications. The merit of the proposition is in whether it is espoused by people "like me". There is no point under dispute other than who is "like me" or "not like me", where "like me" is assumed to be the morally superior state.
The argument from social identity is a sure sign of stupidity. Usually it is invoked with magic words.
EXAMPLE:
"I agree with Richard Dawkins. It is fantastically unlikely that the heritable traits associated with affect, behavior and cognition find equal distribution in all the races of humanity. And to the extent we've measured those distributions, we do indeed find them variable among races, albeit with some minor doubts and mysteries around the edges."
"You, sir, are a racist."
"I happen to be agnostic on the question of whether I am a racist. Do you care to dispute my point?"
"Begone, racist! Trouble us Good People no more!"