It is true that people live in a world of self-deception. They remain aware that it is possible to be deceived by another person-- a family member, a coworker, or a friend-- so they try to ensure that they are not taken advantage of or fooled. They know that if they are deceived that they will have to reap the costs of their error in judgment. It is sort of like a part of the human radar in order to avoid people that are dishonest and greedy--- a social behaviour that was used long ago by our ancestors to do the same for the protection of their families, tribes, territory, and resources.
Deception is prevalent in society among relatives and non-relatives. It takes effort and energy to maintain a straight face and charm in order to deceive others. Whether the deception has to do with telling a lie to get away with something or take advantage of someone the individual has to almost believe their own deception to outwardly give an impression of honesty and genuineness. Not only do they deceive others but they subconsciously deceive themselves. It becomes increasingly difficult for the person to distinguish between what is real and what is superficial and where to draw the line.
It is not easy to understand self-deception from the point of view of a human being. We constantly judge ourselves while judging others and adopt or develop stereotypes in order to understand other people. None of this seems to be based upon our biological nature but rather shaped by our culture. We feel that we are more or less right about our judgments about ourselves and others but we are simply not. We tend to hold biases about different things (i.e. politics, race, gender, age, beauty, wealth, happiness, etc.) that make up part of our moral sense. These biases do not necessarily make up who a person is but instead reflects what society as a whole believes. These beliefs are emphasized in the media in order to get the attention of individuals and mold their opinions--- it is a form of deception. We pick and choose what to believe based on societal 'norms' and in turn deceive ourselves by accepting different biases without really understanding the ideas.
There is truly a cycle of deception which exists in society and it causes human beings to continuously deceive ourselves. Although it is important to detect when someone is being deceptive it is also important to understand that deception exists in all parts of society whether it is in government, business, media, social interactions, religion, education, it is everywhere.
We cannot simply believe something without knowing the basis of the idea or belief. There needs to be a means to understand society. One credible method is to look to science and evolutionary psychology for an understanding of human nature and why our thoughts operate in such a way. We are no more than a biological species with feelings and thoughts but we cannot believe that the basis of our moral sense comes from something beyond our biological limits. In that case, we are simply deceiving and confusing ourselves and driving us further from reality-- from what is true in the realm of our nature. We are only hurting ourselves when we believe what we are not.