To diagnose and treat your company's problems, you can't stop with a second opinion.

Throughout history, leaders at the top of business and government have relied on trusted outsiders to test their ideas and pick apart their assumptions. Clark Clifford, who counseled Democratic and Republican presidents for decades, coined the term for these indispensable yet often unknown advisors: the third opinion. These are the folks who tell the hard truths, who give executives their reality check. Dr. Saj-nicole Joni, a former MIT science professor and Microsoft executive, says the third opinion can be the kind of advice that helps people navigate their way up the corporate ladder. For top-level managers, however, it's paramount - because as they advance, executives become increasingly isolated and find themselves less and less able to get objective input inside their companies.

A third-opinion advisor to some of the top corporate executives in the world, Joni became so convinced of the power of outside perspective that she not only founded Cambridge International Group Ltd., a consulting firm that specializes in it, but she also took three years to interview hundreds of executives and their counselors to better understand how and why the third opinion is so vital. The result is her book, The Third Opinion: How Successful Leaders Use Outside Insight to Create Superior Results (Penguin Group, 2004). American Way recently spoke with Joni about when to seek a third opinion, how to find a good outside advisor, and why that advisor shouldn't give you, well, advice.

Why is the third opinion so important? Good leaders faced with tough issues get a lot of input from all kinds of people around them. They get people who hopefully have the expertise and the resources to help solve the problem, people who have insight into what's going on and who have a vested interest in the outcome.Those are called second opinions. If you're a CEO, you want your head of marketing, your head of sales, and your head of manufacturing to have incredibly passionate vested interests in the outcomes of decisions. Most of the work of leadership is getting the best team of second opinions around you and marshaling them to go somewhere together.

It turns out that for the executive - whether the top person or middle person or early leader - only being in dialogue with people who have a vested interest makes you isolated in certain kinds of thinking. It's very important to also have access to a trusted network of third-opinion advisors so that you do the full realm of thinking. The third opinion is where you seek the right expertise from people with an outside perspective and no vested interest in the outcome. That's the distinction. For many people I work with, it's not that I'm better than their people. But I help them analyze complex choices, and they know they don't have to figure out my spin or agenda.