When one expresses a point of view, that's an opinion.. When one objectively analyzes an opposing point of view that's a sound argument. When one debates another person's point of view and scrutinizes its pros and cons, that is sound and solid reasoning.. But when one negatively attacks an opponent in order to discredit his/her view, then there's a major flaw in logic and it imm...ediately undermines the argument and it loses credibility, as well as the one making the accusations. This fallacious line of argument is called: Argumentum Ad hominem, one of many red herring fallacies. Another most commonly used fallacy is Appeal to Emotions, like fear, where an argument is made by increasing fear and prejudice towards the opposing side here's a link: http://en.wikipedia.org/wiki/
List_of_fallaciesWe're all guilty of falling for these fallacies to endorse our point of view albeit fallaciously, by differing degrees, either knowingly or otherwise.. If you want the other person to listen to what you have to say and have a positive, constructive exchange and hopefully agree on common ground, don't negatively attack them, belittle their point of view or conviction. That is, if you really want them to listen.. But if you're just in it to attack and discredit the other, then there's no thought in that..only a mission and an agenda..