After posting several items on politeness, I began considering the functions that politeness serves and searched the literature. Actually, very little attention has been devoted to politeness functions. What follows is a first attempt to spell out some of the purposes or functions that politeness serves in conversation or in communication generally.
Politeness serves at least seven important functions: (1) to avoid conflict, (2) to ensure cooperative interaction, (3) to manage impressions, (4) to establish power, (5) to ensure compliance, (6) to show deference, and (7) to be nice. The first two of these are widely reported in analyses of politeness (e.g., Eelen, 2001; Watts, 2003; Vilkki, 2006). These functions can best be viewed as goals to be achieved and politeness one of the relevant communication strategies. So, if you want to avoid conflict or ensure cooperative interaction, for example, one communication strategy is to be polite--to support the other person's need for both positive and negative face.
To Avoid Conflict
Politeness can often be used to avoid conflict or to minimize it. Apologizing, which is a classic form of politeness, is an obvious conflict avoider as would be such expressions as you're right, please forgive me, and I was wrong. By being polite you show the other person respect which is likely to lessen any feelings of hostility or even just annoyance. Politeness also helps to create a more positive atmosphere which is likely to help minimize the feelings of conflict and opposition.
To Ensure Cooperative Interaction
By being polite you show that you want the interaction to be cooperative and mutually satisfying. If, at the other extreme, you were rude, the conversation would likely last a lot shorter time and end with ill-feeling. Politeness creates more enjoyment and satisfaction and hence is likely to be pursued at greater length. The small talk on an elevator may also be viewed as a politeness strategy designed to tell the others that you're friendly and are operating with (and within) the established rules of society (i.e., you're not some psychopath).
To Manage Impressions
Consider meeting your new supervisor's family. Here, you're likely to be especially polite to create a desired impression. For example, it will make you appear more likable, certainly an impression you'd want to create. Because politeness demonstrates respect for the other person, the person is apt to respond to you with a certain degree of liking. Politeness here will also make you appear more credible--it takes a certain degree of knowledge and experience to demonstrate politeness, again, a desirable impression to create, whether in the workplace or at the singles club.
To Establish Power
Sometimes a display of politeness--perhaps more in the nature of etiquette--establishes power especially if the other person does not know the rules of social politeness--for eating in a exclusive restaurant or meeting a group of foreign dignitaries or meeting your romantic partner's parents. A person who lacks a knowledge of the rules of politeness is likely to feel awkward and ill-at-ease, making the person less powerful, less likely to be assertive, less likely to engage in argument or even lively discussion, less likely to order escargot (and at this point in my ideal post would be a video of Julia Roberts eating snails in a restaurant in Pretty Woman). Actually, you can see a clip at: http://www.videosurf.com/video/pretty-woman-full-movie-6-12-55084911.
To Ensure Compliance
Politeness is often a persuasive strategy, designed to influence someone to respond more favorably to your message or to gain someone's compliance. Politeness will function like a lubricant to get the wheels of compliance turning. I know you don't like to lend anyone money, and I understand that, but I thought maybe just this once.... Here, you show respect for the person's negative face needs (practicing what we earlier called negative politeness). Or you might laugh at the person's jokes and compliment the person on having a great sense of humor as a preface to asking a favor. Here you respond to the person's positive face needs to be thought of highly (practicing positive politeness).
To Show Deference
Politeness to show deference is probably the function of politeness that comes most quickly to mind and yet, clearly, is not the only function. But, it's an important one. Politeness is often a sign of deference as when a young person addresses an older person with Title + Last Name while being addressed with just First Name or a student addresses a professor with the honorific "professor" but receives a first name in return. One great scene occurs in In the Heat of the Night where Sidney Poitier responds to Rod Steiger's "What do they call you?" with "They call me Mr. Tibbs," a brief way of demanding respect and due deference. This line, btw, is rated Number 76 in the all time great movie lines by Premiere magazine (2007) and Number 16 in "movie quotes" by the American Film Institute (as reported on The Internet Movie Database (www.imdb.com/title/tt0061811/trivia). Take a look at the Premiere.com website for the entire list of 100 lines--the first, btw, is: "Here's looking at you, kid" from Casablanca.
In some cultures, this function of politeness is more important than others. In Japan, which is generally used as the society in which politeness rules are most important, one way to show deference is with the bow; a lower status person (say a junior executive) bows lower and for a longer length of time when meeting a higher status person (say the president of the corporation) who bows relatively little. In many European languages, you show deference by using different pronouns--the more formal pronouns showing greater politeness. In English, as in most languages, you have politeness tags--words like please and thank you--that signal politeness. An overuse or an underuse of these politeness tags may signal not deference but a low social status, a discomfort with the social situation, or a general lack of knowledge of the rules of social interaction.
To Be Nice
If you were to ask people why they are polite, they'd probably say something to the effect that it's the nice thing to do--you act politely to be nice without any attempt to manipulate the other person or to create a favorable impression of yourself. However, determining when someone is being polite just to be nice and when someone is being polite for some ulterior motive is another story.