Making bad decisions is all part of being a leader. But one way to avoid them might be firing your "yes men." 

Noreena Hertz writes in the Harvard Business Review that every CEO needs a "Challenger in Chief," or someone who voices dissent. Having access to several opinions, she says, might improve group-think, lessen bias, and help executives find smarter solutions. 

"When group members are actively encouraged to openly express divergent opinions they not only share more information, they consider it more systematically and in a more balanced and less biased way," she writes. "When people engage with those with different opinions and views from their own they become much more capable of properly interrogating critical assumptions and identifying creative alternatives."

Hertz references a study by Small Group Research, which found that decision-making groups (think the board of directors) are biased by design. As a result, groups comprised of people with different opinions speak up, which leads to better decisions. Most leaders, however, won't encourage this, especially at work. 

At Lehman Brothers, for example, there was an unspoken rule: Voice dissent and you're going to get fired. Before Lehman's demise, the board of directors and management were so agreeable no one dared to say their decisions were leading them right into the financial crisis.

One leader famous for embracing dissent was President Abraham Lincoln. He constantly met with a "team of rivals," who helped guide his decisions through intellectual debate. Eric Schmidt, Google's executive chairman, is also known for hiring workers who disagree. 

Leaders are just like everyone else. When they're stressed, they depend on stereotypes, and if their blood sugar drops, they make poorer financial decisions. If they don't get enough sleep, their brains behave as if they are drunk

A "Challenger in Chief" might stave off bad decisions, save your company from ruin, or help the country. But more than anything, it will make you a great leader.