Argumentum Ad Hominem is an argument which states that a person is wrong because
of something that amounts to a personal attack and is completely unrelated to the persons position.
It roughly translates to Argument by attack on the man.
Ad Hominem is a fallacy that is frequently misunderstood and confused with being rude or insulting while presenting an argument.
Being rude or insulting while presenting an argument is not a fallacy and while some may not appreciate that approach, it doesn't take away from the correctness or incorrectness of the argument presented.
For eg. the following are insulting or rude but not Ad Homs
1. Person B is a dick.
2. Person B believes X and that's a stupid thing to believe so they're a moron.
The following is a correct formulation of the format of the Ad Hom.
"Ad hominem" is an association fallacy. It relies on a flaw regarding the logical association. Simply put, ad hominem works like this:
(1) Person A's argument is X.
(2) Person B makes an irrelevant attack on person A
(3) Therefore, person A's argument is false.
Source: Ad Hominem
Essentially Person As argument becomes false because of the personal attack.
Eg. You're an immoral atheist so what could you know about the Bible or morality.
Note that the above statement is an Ad Hominem but doesn't contain swearing or direct insults or direct rudeness.
The term "immoral atheist" is what constitutes the personal attack. It constitutes an unwarranted negative assumption about atheists.
This personal attack is then fallaciously associated with "ignorance of morality and the bible".
Here are some more variations on Argumentum Ad Hominem:
"Another variation is attack by innuendo: "Why don't scientists tell us what they really know; are they afraid of public panic?"
There may be a pretense that the attack isn't happening: "In order to maintain a civil debate, I will not mention my opponent's drinking problem." Or "I don't care if other people say you're [opinionated/boring/overbearing]."
Attacks don't have to be strong or direct. You can merely show disrespect, or cut down his stature by saying that he seems to be sweating a lot, or that he has forgotten what he said last week. Some examples: "I used to think that way when I was your age." "You're new here, aren't you?" "You weren't breast fed as a child, were you?" "What drives you to make such a statement?" "If you'd just listen.." "You seem very emotional." (This last works well if you have been hogging the microphone, so that they have had to yell to be heard.)
Sometimes the attack is on the other person's intelligence. For example, "If you weren't so stupid you would have no problem seeing my point of view." Or, "Even you should understand my next point."
Oddly, the stupidity attack is sometimes reversed. For example, dismissing a comment with "Well, you're just smarter than the rest of us." (In Britain, that might be put as "too clever by half".) This is Dismissal By Differentness. It is related to Not Invented Here and Changing The Subject.
Ad Hominem is not fallacious if the attack goes to the credibility of the argument. For instance, the argument may depend on its presenter's claim that he's an expert. (That is, the Ad Hominem is undermining an Argument From Authority.) Trial judges allow this category of attacks."
Source: List of Fallacious Arguments.
Does anyone have any other good examples of Ad Hominem?