Many of us have had the experience of working for someone who was...let’s just say... not smart. You may have wondered exactly how the boss got the job in the first place. Does a company leader need to be smart in order to be a successful leader? Should a company only hire leaders who are intelligent?

There are scores of leadership characteristics advocated for in books, articles, and the speaking circuit that distinguish successful leaders from unsuccessful ones. Emotional intelligence, charisma, inspiration, integrity, confidence, and intuition, are amongst these characteristics. But, no matter how they are grouped together, they are normally presented without indication of which ones are more important than the others, as though each of them is equally necessary for success. In other words, we are left to assume that no evidence exists that any characteristic is more important than others.

This is not the case. Though the best leaders need many characteristics, one is more consistently predictive of leadership success than any other. Regardless of setting, general cognitive ability is the most reliable predictor of job performance and occupational level (Schmidt & Hunter, 2004). It is more predictive of job performance than personality. Further, the effects of better cognitive ability don’t go away as leaders get more job experience (Schmidt & Hunter, 2004). This is because those with higher general mental ability acquire more job knowledge in a more efficient way than those with lower ability. So, the differences persist.

However, one of the difficulties with general mental ability is how to test for it in prospective leaders. Using a traditional IQ test would likely not be received well by applicants for leadership positions because it measures the verbal, quantitative, and spatial reasoning skills needed to succeed in school. Though IQ is predictive of job success, it doesn’t seem to reflect the situations leaders are confronted with that are ambiguous, complex, and lack an easily identifiable right answer .

Critical thinking has recently received attention as the best application of intelligence of business leaders. According to the U.S. Department of Labor’s description of job skills in their O*NET database, critical thinking is the use of “logic and reasoning to identify the strengths and weaknesses of alternative solutions, conclusions or approaches to problems.” In the business context, Menkes (2005) indicated that, rather than representing intelligence as the academic skills needed in school, business leaders need critical thinking in the following three general areas: tasks, people, and themselves (see the Menkes article for a complete list of specific skills). The leader that you want in your company will use their reasoning skills to gather needed information, evaluate the situation, and arrive at the best conclusions in each of these areas.

Your company needs to hire leaders who are experts at using critical thinking skills to determine their decisions and actions. While there are off-the-shelf tests available that measure executive intelligence, companies can evaluate critical thinking skills effectively in their interview, provided they are asking the right questions.