To believe that the people who commit fraud are different from us might make us feel safe. But real safety comes from building an organization that stops these acts before they can take place.

By Eleanor Bloxham, CEO of The Value Alliance and Corporate Governance Alliance

FORTUNE -- Dennis Levine, who lectured an NYU MBA ethics class as part of his community service many years ago, described the mentality that led to his insider trading conviction as a mentality of having to win the next game, competing with oneself for the next victory, where enough was never enough.

His explanation is applicable to both individuals and entire corporate cultures, such as MF Global (MFGLQ) and Olympus, where losses were allegedly buried from public view on purpose.

But Levine's explanation doesn't address why enough is never enough. What underlies the motivations to hide losses? And why does it often take a very rude awakening for a person (or a company) to change?

What has befallen Olympus has been chalked up to an obedience culture, a management team that was "rotten at the core," and a board "of yes men." MF Global's case has been explained away by  Jon Corzine's hubris. But if we examine, rather than impugn, Corzine's motives  and those of the board and executives at Olympus, we will realize how these individuals' actions relate to you and me.

As almost any good board member will tell you, the responsibility for corporate culture, or what is commonly referred to as "tone at the top," begins with the board. Good board members monitor the CEO and corporate culture by meeting not only with the CEO but also with other members of a company's management team in social settings, on site visits, in executive sessions without other members of management present, and in regular board and committee meetings. They don't just listen to management speeches: they read body language, observe interactions, and view facilities. They look at the contents of whistle-blower and customer hotline call-in logs, employee surveys, performance evaluations, and compensation decisions. They carefully and systematically gauge the level of healthy dissent and openness to discuss troubling situations and imperfect solutions. More