I can’t speak for everybody, but I have layers that I put on and take off based on the social situation I find myself in. When I’m by myself I can let my thoughts flow freely around any topic: why I haven’t gone to see “The Passion of the Christ” yet or what I think about same-sex marriage, etc.
If my wife is with me I will add a very thin layer that is designed to filter my outbound opinions. The point of the layer is to ensure that my thoughts are communicated clearly but in a way that won’t cause marital discord.
Put me in a public place where my conversation may be overheard — like a store or a restaurant — and another layer is added to scrub anything that might be interpreted as rude or inflammatory by others. This may be as simple as keeping my potty mouth in check while children are around or as complex as avoiding the use of gender-specific pronouns when replying to someone whose yellow clad, androgynous-looking child has been brought to my attention. This layer still has as its goal the clear communication of the ideas filtered through it, but it will also ensure that certain topics are avoided until more privacy is available.
Finally, put me in church or any other place where I assume that everyone around me holds a given set of social and political views and I’ll add a final layer to keep anything I say from conflicting with these “acceptable” positions. This is mostly an expedient. I assume that I know your opinion, I don’t care to explain mine, so let’s just keep our conversation paper thin and puddle shallow and get through all of our interactions with as little friction as possible. That after all is the nub of civility, right?
The purpose of this final layer in not the clear communication of my thoughts. This layer ensures easy headway through the crowd. This layer answers the question, “How are you?” with the pat answer, “I’m fine, and you?” I may not be fine but I’m not going to tell you about it here. You probably asked the question just to be polite anyway. My pat answer is polite too.
So now you know about my layered personality: my social situation determines the amount of variance between what I think and what I say. While I would never filter my opinion so radically that I end up lying about what I think, I may filter my words so carefully that you’d never have reason to suspect that my opinion is different than the pervasive “acceptable” view. I’m drawing a distinction here between the intention to deceive and the willingness — or possibly even the desire — to be incorrectly perceived.