In more than thirty-five years of consulting, I have found that, at the upper echelons of large organizations, natural intelligence differentiates the successful leader from the “also ran.” While you’ll hear debates about the roles of emotional intelligence, vision, and the ability to motivate others, brainpower trumps all. Three main components define what I call Executive Intelligence: Critical thinking, learning ability, and quantitative skills. Of these, critical thinking—that “lick of sense” you hear so much about—is the most important and the least understood.

I have often said that a smart sociopath is a leader’s worst nightmare. These snakes in business casual generate more havoc in a shorter period of time than anyone else—and they often make doing so look good, at least in the short run.

But we don’t give enough attention to the second biggest problem: the overachieving, nose-to-the-grindstone, works-sixty-hours-a-week go-getter idiot. These people proudly put in more face time than anyone else, take the jobs that other eschew, and smugly announce that they have no time for a balanced life because their work defines them.  Although this list contains laudable behaviors, the operative word we should consider is “idiot.”