What we have found, in a nutshell: Everybody has the capacity to be dishonest, and almost everybody cheats—just by a little. Except for a few outliers at the top and bottom, the behavior of almost everyone is driven by two opposing motivations. On the one hand, we want to benefit from cheating and get as much money and glory as possible; on the other hand, we want to view ourselves as honest, honorable people.
This is fascinating research, but the "why" alluded to in the title is never revealed. The "who" stands as an homage to Gregory House: "Everybody Lies." The interesting information provided within is the "when."
My philosophical take on the "why" is that, unlike the humanistic ideal, people are not essentially good. We know what is good and what isn't, and we want to be perceived as good. Yet we still do the opposite.
Some could certainly consider lying a small thing, and perhaps not even an unethical thing. But it's illustrative of the general case: no one can consistently live up to ethical standards -- whether one's own, one's religion's, or one's community's. We see the macro effects of this in issues of obvious evil such as genocide, but we dismiss those as abberations. However, the behavior is ubiquitous and touches every standard we adopt, no matter how small.
