Ever have a "discussion" on Facebook where your correspondent resorts to personal comments about you (or another) that are not relevant to the topic?
This fallacious technique is called ad hominem — Latin for “to the man,” attacking the arguer and not the argument. They take many forms, with some being very subtle. A variant is guilt by association. Watch for them.
This is a classic. It associates those who would ban assault rifles with some pretty nasty people, thus implying that those supporting the ban are similarly nasty. The merits of banning assault rifles are not addressed, with the arguer shifting to a personal attack. Pure argumentum ad hominem.
Interestingly, argumentum ad hominem, is a subset of genetic fallacy: a line of "reasoning" in which a perceived defect in the origin of a claim or thing is taken to be evidence that discredits the claim or thing itself.
It is also a line of reasoning in which the origin of a claim or thing is taken to be evidence for the claim or thing. Here are examples:
1. "The current Chancellor of Germany was in the Hitler Youth at age 3. With that sort of background, his so called 'reform' plan must be a facist program."
2. "I was brought up to believe in God, and my parents told me God exists, so He must."
3. "Sure, the media claims that Senator Bedfellow was taking kickbacks. But we all know about the media's credibility, don't we?"