Rhetoric in opinion pieces

Opinion pieces are simple forms of writing intended to express an opinion, convince an audience, and in some cases, call the audience to action.
An opinion piece arguably has two purposes, one is to express an opinion, and the other is to convince the public of the opinion. Of course the first part is much easier to do. Convincing the audience is where the bulk of the author's rhetorical strategies come into play. Most editorials use deductive reasoning, by which they will first make a statement, and then go into more depth and present evidence in order to prove that statement. If the author of the opinion piece is writing about sciences, he/she will use evidence from scholarly and reliable sources generally. If the editorial piece is meant to be a simple insult of someone (as was the case with the article criticizing Caesar Milan), then the author will more likely use observations made by himself or herself, possibly quotes from various people, and maybe a few statistics to help drive home their point.
The tone of editorial pieces varies, however most of the ones I have recently read have taken on a condescending and sarcastic tone. The author is generally acting in a condescending view towards the other opinion, or specifically, the supporters of other opinions. This appeals to the audience because it makes them feel as though the author of the editorial knows enough and is powerful enough that he/she can treat his opposition like a child, and not like a worthy adversary.
Opinion pieces that are not condescending are generally more alarmist and generally call for action. They tend to bring forward more evidence to support the author's views, and take less jabs at the opposition. They try to make their cause seem like an immediate necessity, and usually end up telling the audience that they need to bring about some change.