You might think the obvious answer is yes. After all, cognitive capacity is the single best predictor of job performance across a wide range of occupations. But the relationship between IQ and presidential greatness, while present, is not necessarily large.
How to estimate presidential IQ
In a 2006 study, the psychologist Dean Keith Simonton assessed presidential intelligence by asking independent judges to rate presidents’ personality traits from George Washington through Ronald Reagan using 300 descriptors extracted from biographical sources. Simonton’s statistical analysis of these 300 descriptors identified 14 distinct personality dimensions, including one that encompasses such items as “intelligent,” “wise” and related traits. This measure of presidential intelligence was related to features of their biographies, to earlier assessments of presidential intelligence by other scholars, and to personality traits known to be linked to intelligence in the general population.
Simonton used these estimates to impute several different IQ scores for the 42 presidents through George W. Bush. All the scores are highly correlated. (We use the score that accounts for the fact that there are varying amounts of biographical information for different presidents.) These scores ranged from 130 to 175, with an average of about 147. This is considerably higher than the average among Americans of 97.5. From the development of our current two-party system to the presidency of George W. Bush, the nine Democratic presidents had somewhat higher IQs, on average, than the 18 Republicans (143.7 vs. 149.5). This difference is statistically significant, but it is unclear whether it is large enough to be substantively meaningful.
Revisiting the link between IQ and presidential success
In his research, Simonton found a positive link between IQ and presidential greatness. We have reassessed that link by examining a different measure of presidential greatness: expert rankings compiled by a 2017 C-SPAN poll of 91 historians and other professional observers of the presidency.
These participants were drawn from a database of C-SPAN’s programming with input from an academic advisory team that consisted of presidential biographers, historians and political scientists. C-SPAN asked these experts to evaluate the presidents on 10 qualities of presidential leadership including public persuasion, crisis leadership, economic management, moral authority, international relations, administrative skills, relations with Congress, vision/setting an agenda, pursuing equal justice for all, and “performance within the context of his times.” The experts’ responses were combined to produce an overall score, ranging from 245 (James Buchanan) to 907 (Lincoln).
We find that presidents with high IQs tend to be considered more successful. The graph below shows this relationship. For each additional point in IQ, estimates of presidential success grow by about five points, all else being equal. At the same time, the correlation is not extraordinarily large (0.24, where the maximum positive correlation of 1).
But as we know, correlation is not necessarily causation. Some very smart presidents were not considered very successful. One example is John Quincy Adams, who had the highest IQ score but only middling success, at least according to these expert evaluations. James Madison and Jimmy Carter also had impressive IQs but more limited success.
Conversely, some presidents with lower IQs, relative to other presidents, were viewed as very successful. George Washington and Harry S. Truman are two examples.
Ultimately, maybe Trump is as smart as he says he is. But, thus far, experts believe he is struggling. And history tells us that smarts don’t guarantee a successful presidency.
Costas Panagopoulos is a professor of political science and director of Big Data and Quantitative Methods Initiatives at Northeastern University, and author of “Political Campaigns: Concepts, Context and Consequences” (Oxford University Press, 2016). Find him on Twitter @professorcostas.
Kendall Bailey is a PhD candidate in the Department of Political Science at Northeastern University.