IHere is a puzzle: effectiveness in senior leadership positions in government does not seem to be well correlated with intelligence. Washington was a better President than Jefferson, though less able intellectually. Franklin Roosevelt, Harry Truman, Dwight Eisenhower, and Ronald Reagan were not as bright as Herbert Hoover, Richard Nixon, Jimmy Carter, or Bill Clinton. Lincoln, a brilliant lawyer, is an exception; Theodore Roosevelt perhaps another exception; and doubtless there are others. But overall the correlation between intelligence and effectiveness in the Presidency may actually be negative. Even more striking are the failures of Kennedy and Johnson's national security team in Vietnam and George W. Bush's national security team in Iraq. McNamara and his whiz kids (such as Daniel Ellsberg, Harold Brown, and Alan Enthoven), the Bundies, Walt Rostow, George Ball‚Äîthese were extremely able people, many of them (like McNamara and McGeorge Bundy) truly brilliant. And Bush assembled an outstanding national security team--Cheney, Rumsfeld, Powell, Wolfowitz, Rice, Tenet (appointed by Clinton but held over by Bush). Two members of the team--Cheney and Rumsfeld--were former secretaries of defense! And Powell was a former chairman of the joint chiefs of staff. It could just be bad luck, but I think not. Economists distinguish between general and specific human capital, the first created by IQ and education and the second by training and experience in a particular job. A person who has a large amount of general human capital is likely to find a job in which that capital, augmented by on the job training and experience, is highly productive. The resulting success will make him an attractive candidate for a high-level government job. The high-level jobs are filled generally by lateral entries from quite different jobs, rather than by civil servants. Some of these high-level jobs are technical; an example is the chairmanship of the Federal Reserve Board. Such jobs are relatively easy to fill with persons who can be predicted with reasonable confidence to do a good job. But there is a tendency to exaggerate the versatility of the combined general-specific human capital that a lateral entrant brings to a high-level government job of a managerial or advisory rather than technical character. There are several characteristics of such a job that actually militate against the prospects for the success of an extremely intelligent person. First, these are "ensemble" jobs in the sense that many different skills or aptitudes are necessary to successful performance; if one of these, such as intelligence, is very highly developed, a person may neglect the others. Second, it may not be possible to use step-by-step, logical reasoning to solve the problems laid at the feet of the occupant of a job like secretary of defense or secretary of state or national security adviser. Such questions as what to do in Vietnam or what to do in Iraq do not lend themselves to rigorous analysis because there is not enough information to analyze. Intelligence is not designed for coping with situations that are not complex, but rather are profoundly uncertain. Having great information-processing skills is not worth a lot if you have no reliable information. Third, leaders or managers should be more intelligent than their followers or subordinates, but not too much more intelligent. If they are too much more intelligent, they will have difficulty assessing the capacities and limitations of their underlings and they will be tempted to substitute their intelligence for their underlings' knowledge. Analysis and knowledge are, to an extent, substitutes. You can multiply two numbers rapidly if you have good computational skills or if, though your computational skills are mediocre, you have memorized the multiplication table. Knowledge in government resides in civil servants, and they tend on average to be less intelligent (also of course less powerful) than brilliant laterals. So the latter are tempted to think that they can make decisions with minimal assistance from the civil servants. The temptation is reinforced by a failure to distinguish between intuition and step-by-step reasoning. Cognitive psychologists explain that the human unconscious contains more information than we can access at a conscious level. As Herbert Simon (an economist and psychologist) explained, conscious attention is a severely limited faculty and must be carefully rationed. Through intuition, however, we can access the larger repository of unconscious information. Hence we speak of a person as having "experience" or "good judgment" or "common sense," as distinguished from being brilliant in the sense of being quick or having a good (conscious) memory. So now imagine a confrontation between a brilliant person who has no knowledge about Vietnam or Iraq, and a career State Department officer who has spent his whole career working on conditions in one of those countries, who knows the language, has lived there, and is steeped in the country's history, culture, and politics. Suppose he offers some advice to the brilliant senior official, and the latter asks him to explain and justify the advice. He may be unable to do so because he may be drawing on a repository of information below the conscious level. The brilliant official may be irritated at his inability to extract much more than a conclusion from the expert. What is required at the top levels of government is not brilliance, but managerial skill, which is a different thing, and includes knowing when to defer to the superior knowledge of a more experienced but less mentally agile subordinate. Moreover, so specialized is management as a job that success in managing a business may not translate at all into success in managing a government agency. The firm-specific human capital that a person acquired in a career of management in a business firm may have no value for the management of a government agency, or for that matter a university, a private foundation, or an international organization. Indeed, an experienced manager of a firm may falter and have to be fired if a change in the firm's environment requires a different type of management skill. A striking example of the specialized character of leadership human capital is Larry Summers. A truly brilliant person and successful secretary of the treasury, he failed as president of Harvard University though he seemed to many people (myself included) to be an outstanding choice. I have the highest personal and professional regard for Summers and blame the failure of his presidency not on him but on the Harvard faculty of arts and sciences. But the fact is that he failed, because he was not able to port his very considerable suite of intellectual and managerial assets to the management of an organization critically different from the Treasury Department.