You certainly know that just because someone is a civil engineer, does not mean he or she is polite (likewise the character of criminal attorneys, the authenticity of plastic surgeons and the vehicular preferences of bus boys). But civil society should reflect respect for everyone and a desire to behave better than one thinks other people deserve.
For all of the complaining we do about the nature of interaction among various political candidates, they are only offering what the market will bear. As I have mentioned many times, in a contest that rewards winners and consigns losers to a footnote, polite behavior is generally reserved for after the election, when graciousness is the only true sign that the polls have finally closed.
Is our own behavior cause or effect? Honestly, it matters little to me. Our own behavior is the only behavior we control.
Rabbi Israel Meir HaCohen Kagan was known as the Chafetz Chaim, the "Desirer of Life" (after the verse in Psalms that prescribes stopping your tongue from evil and your lips from deceit as the prescription for those who desire life). He practiced an almost impossibly scrupulous standard of purity of speech and non-verbal communication. It is easy to despair of our ability to be civil when we read his prescriptions and observe his example.
Mostly, however, he commends that each of us be conscious of how our words and actions will be interpreted by others. Quiet intentions mean little if actions communicate loudly. A corrective comment may be taken as a personal insult; overly effusive praise of one person may make another feel neglected. And even innocent "objective" descriptions may carry unintended inferences – like our aforementioned civil engineer and criminal attorney.
Here in the congregation that consciousness can go a long way in avoiding hurt feelings. A gregarious greeting to a friend may be seen as purposeful neglect when not offered to an acquaintance. An expression of concern about details of a suggestion may be understood as a critique of diligence by its proponent. A criticism of style may be perceived as a character referendum by a casual listener.
If each of us is more conscious of how we express ourselves, with an eye toward civility, we can model appropriate conduct to those around us. And when an acquaintance violates those civil boundaries, a gentle but direct suggestion can provide the necessary corrective.