On the bottom page 333 of the Lilienfeld text, the authors' support the idea of IQ scores predicting life outcomes by looking at past president's IQ scores and their quality of leadership. Dean Keith Simonton estimated the IQ scores for all U.S. presidents through George W. Bush. For each president, there is a 10-20 point IQ range that estimates their IQ score. He then compared the estimated IQ scores to the quality of leadership for each president, and found a moderate correlation between the two statistics. The authors of the book then used this correlation to show that IQ scores predict life outcomes, but circular reasoning shows that this may not be a correlation at all.
Because the actual IQ scores for all of the presidents are not known, Dean Keith Simonton would have to look at historical data in order to estimate them. He would have to look at accomplishments, decisions, and documents about each of the presidents. By looking at the things that each president did and said during their presidency, an IQ score was then estimated. He then compared the IQ to each president's "quality of leadership" and then found a correlation. This is actually not a correlation at all, because the same data and judgement that was used to predict each president's IQ was more than likely the same data and judgement that was used to judge their "quality of leadership".
When looking at past president's popularity rankings, the findings are eerily similar to Simonton's IQ estimates. Unpopular presidents such as Warren Harding, the president at the beginning of the great depression, are both extremely low in popularity and rated as one of the least intelligent president's on Simonton's list. Presidents high in popularity, such as Lincoln and FDR, also have some of the highest IQ's on the list. Although IQ could be a strong indicator on popularity because they are both positive attributs, we don't know that for sure. When historians are the one's assigning IQ scores to presidents, it seems silly to prove a correlation by comparing it to a different historian's presidential rankings. President's IQ could be a strong indicator of their quality of leadership, but when we don't know their actual IQ scores, we cannot prove a correlation by using estimates.