What distinguishes exemplary boards is that they are robust, effective social systems … The highest performing companies have extremely contentious boards that regard dissent as an obligation and that treat no subject as undiscussable.

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Perhaps the most important…is the capacity to challenge one another’s assumptions and beliefs. Respect and trust do not imply endless affability or absence of disagreement. Rather, they imply bonds among board members that are strong enough to withstand clashing viewpoints and challenging questions.